1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653
|
<?xml version="1.0" encoding="UTF-8"?>
<!-- Reviewed: no -->
<sect1 id="zend.db.table">
<title>Zend_Db_Table</title>
<sect2 id="zend.db.table.introduction">
<title>Introduction</title>
<para>
The <classname>Zend_Db_Table</classname> class is an object-oriented interface to
database tables. It provides methods for many common operations on tables. The base
class is extensible, so you can add custom logic.
</para>
<para>
The <classname>Zend_Db_Table</classname> solution is an implementation of the
<ulink url="http://www.martinfowler.com/eaaCatalog/tableDataGateway.html">Table Data
Gateway</ulink> pattern. The solution also includes a class that implements the
<ulink url="http://www.martinfowler.com/eaaCatalog/rowDataGateway.html">Row Data
Gateway</ulink> pattern.
</para>
</sect2>
<sect2 id="zend.db.table.concrete">
<title>Using Zend_Db_Table as a concrete class</title>
<para>
As of Zend Framework 1.9, you can instantiate <classname>Zend_Db_Table</classname>. This
added benefit is that you do not have to extend a base class and configure it to do
simple operations such as selecting, inserting, updating and deleteing on a single
table. below is an example of the simplest of use cases.
</para>
<example id="zend.db.table.defining.concrete-instantiation.example1">
<title>Declaring a table class with just the string name</title>
<programlisting language="php"><![CDATA[
Zend_Db_Table::setDefaultAdapter($dbAdapter);
$bugTable = new Zend_Db_Table('bug');
]]></programlisting>
</example>
<para>
The above example represents the simplest of use cases. Make not of all the
options describe below for configuring <classname>Zend_Db_Table</classname> tables. If
you want to be able to use the concrete usage case, in addition to the more complex
relationhip features, see the <classname>Zend_Db_Table_Definition</classname>
documentation.
</para>
</sect2>
<sect2 id="zend.db.table.defining">
<title>Defining a Table Class</title>
<para>
For each table in your database that you want to access, define a class that extends
<classname>Zend_Db_Table_Abstract</classname>.
</para>
<sect3 id="zend.db.table.defining.table-schema">
<title>Defining the Table Name and Schema</title>
<para>
Declare the database table for which this class is defined, using the protected
variable <varname>$_name</varname>. This is a string, and must contain the name of
the table spelled as it appears in the database.
</para>
<example id="zend.db.table.defining.table-schema.example1">
<title>Declaring a table class with explicit table name</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
}
]]></programlisting>
</example>
<para>
If you don't specify the table name, it defaults to the name of the class. If you
rely on this default, the class name must match the spelling of the table name as
it appears in the database.
</para>
<example id="zend.db.table.defining.table-schema.example">
<title>Declaring a table class with implicit table name</title>
<programlisting language="php"><![CDATA[
class bugs extends Zend_Db_Table_Abstract
{
// table name matches class name
}
]]></programlisting>
</example>
<para>
You can also declare the schema for the table, either with the protected variable
<varname>$_schema</varname>, or with the schema prepended to the table name in the
<varname>$_name</varname> property. Any schema specified with the
<varname>$_name</varname> property takes precedence over a schema specified with the
<varname>$_schema</varname> property. In some <acronym>RDBMS</acronym> brands, the
term for schema is "database" or "tablespace," but it is used similarly.
</para>
<example id="zend.db.table.defining.table-schema.example3">
<title>Declaring a table class with schema</title>
<programlisting language="php"><![CDATA[
// First alternative:
class Bugs extends Zend_Db_Table_Abstract
{
protected $_schema = 'bug_db';
protected $_name = 'bugs';
}
// Second alternative:
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bug_db.bugs';
}
// If schemas are specified in both $_name and $_schema, the one
// specified in $_name takes precedence:
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bug_db.bugs';
protected $_schema = 'ignored';
}
]]></programlisting>
</example>
<para>
The schema and table names may also be specified via constructor configuration
directives, which override any default values specified with the
<varname>$_name</varname> and <varname>$_schema</varname> properties. A schema
specification given with the <property>name</property> directive overrides any value
provided with the <property>schema</property> option.
</para>
<example id="zend.db.table.defining.table-schema.example.constructor">
<title>Declaring table and schema names upon instantiation</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
}
// First alternative:
$tableBugs = new Bugs(array('name' => 'bugs', 'schema' => 'bug_db'));
// Second alternative:
$tableBugs = new Bugs(array('name' => 'bug_db.bugs'));
// If schemas are specified in both 'name' and 'schema', the one
// specified in 'name' takes precedence:
$tableBugs = new Bugs(array('name' => 'bug_db.bugs',
'schema' => 'ignored'));
]]></programlisting>
</example>
<para>
If you don't specify the schema name, it defaults to the schema to which your
database adapter instance is connected.
</para>
</sect3>
<sect3 id="zend.db.table.defining.primary-key">
<title>Defining the Table Primary Key</title>
<para>
Every table must have a primary key. You can declare the column for the primary key
using the protected variable <varname>$_primary</varname>. This is either a string
that names the single column for the primary key, or else it is an array of column
names if your primary key is a compound key.
</para>
<example id="zend.db.table.defining.primary-key.example">
<title>Example of specifying the primary key</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
protected $_primary = 'bug_id';
}
]]></programlisting>
</example>
<para>
If you don't specify the primary key, <classname>Zend_Db_Table_Abstract</classname>
tries to discover the primary key based on the information provided by the
<methodname>describeTable()</methodname>´ method.
</para>
<note>
<para>
Every table class must know which columns can be used to address rows
uniquely. If no primary key columns are specified in the table class
definition or the table constructor arguments, or discovered in the table
metadata provided by <methodname>describeTable()</methodname>, then the table
cannot be used with <classname>Zend_Db_Table</classname>.
</para>
</note>
</sect3>
<sect3 id="zend.db.table.defining.setup">
<title>Overriding Table Setup Methods</title>
<para>
When you create an instance of a Table class, the constructor calls a set of
protected methods that initialize metadata for the table. You can extend any of
these methods to define metadata explicitly. Remember to call the method of the
same name in the parent class at the end of your method.
</para>
<example id="zend.db.table.defining.setup.example">
<title>Example of overriding the _setupTableName() method</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected function _setupTableName()
{
$this->_name = 'bugs';
parent::_setupTableName();
}
}
]]></programlisting>
</example>
<para>
The setup methods you can override are the following:
</para>
<itemizedlist>
<listitem>
<para>
<methodname>_setupDatabaseAdapter()</methodname> checks that an adapter has
been provided; gets a default adapter from the registry if needed. By
overriding this method, you can set a database adapter from some other
source.
</para>
</listitem>
<listitem>
<para>
<methodname>_setupTableName()</methodname> defaults the table name to the
name of the class. By overriding this method, you can set the table name
before this default behavior runs.
</para>
</listitem>
<listitem>
<para>
<methodname>_setupMetadata()</methodname> sets the schema if the table name
contains the pattern "<command>schema.table</command>"; calls
<methodname>describeTable()</methodname> to get metadata information;
defaults the <varname>$_cols</varname> array to the columns reported by
<methodname>describeTable()</methodname>. By overriding this method, you can
specify the columns.
</para>
</listitem>
<listitem>
<para>
<methodname>_setupPrimaryKey()</methodname> defaults the primary key columns
to those reported by <methodname>describeTable()</methodname>; checks that
the primary key columns are included in the <varname>$_cols</varname> array.
By overriding this method, you can specify the primary key columns.
</para>
</listitem>
</itemizedlist>
</sect3>
<sect3 id="zend.db.table.initialization">
<title>Table initialization</title>
<para>
If application-specific logic needs to be initialized when a Table class is
constructed, you can select to move your tasks to the
<methodname>init()</methodname> method, which is called after all Table metadata has
been processed. This is recommended over the <methodname>__construct()</methodname>
method if you do not need to alter the metadata in any programmatic way.
</para>
<example id="zend.db.table.defining.init.usage.example">
<title>Example usage of init() method</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_observer;
public function init()
{
$this->_observer = new MyObserverClass();
}
}
]]></programlisting>
</example>
</sect3>
</sect2>
<sect2 id="zend.db.table.constructing">
<title>Creating an Instance of a Table</title>
<para>
Before you use a Table class, create an instance using its constructor. The
constructor's argument is an array of options. The most important option to a Table
constructor is the database adapter instance, representing a live connection to an
<acronym>RDBMS</acronym>. There are three ways of specifying the database adapter to a
Table class, and these three ways are described below:
</para>
<sect3 id="zend.db.table.constructing.adapter">
<title>Specifying a Database Adapter</title>
<para>
The first way to provide a database adapter to a Table class is by passing it as an
object of type <classname>Zend_Db_Adapter_Abstract</classname> in the options array,
identified by the key '<property>db</property>'.
</para>
<example id="zend.db.table.constructing.adapter.example">
<title>Example of constructing a Table using an Adapter object</title>
<programlisting language="php"><![CDATA[
$db = Zend_Db::factory('PDO_MYSQL', $options);
$table = new Bugs(array('db' => $db));
]]></programlisting>
</example>
</sect3>
<sect3 id="zend.db.table.constructing.default-adapter">
<title>Setting a Default Database Adapter</title>
<para>
The second way to provide a database adapter to a Table class is by declaring an
object of type <classname>Zend_Db_Adapter_Abstract</classname> to be a default
database adapter for all subsequent instances of Tables in your application. You can
do this with the static method
<methodname>Zend_Db_Table_Abstract::setDefaultAdapter()</methodname>. The argument
is an object of type <classname>Zend_Db_Adapter_Abstract</classname>.
</para>
<example id="zend.db.table.constructing.default-adapter.example">
<title>Example of constructing a Table using a the Default Adapter</title>
<programlisting language="php"><![CDATA[
$db = Zend_Db::factory('PDO_MYSQL', $options);
Zend_Db_Table_Abstract::setDefaultAdapter($db);
// Later...
$table = new Bugs();
]]></programlisting>
</example>
<para>
It can be convenient to create the database adapter object in a central place of
your application, such as the bootstrap, and then store it as the default adapter.
This gives you a means to ensure that the adapter instance is the same throughout
your application. However, setting a default adapter is limited to a single adapter
instance.
</para>
</sect3>
<sect3 id="zend.db.table.constructing.registry">
<title>Storing a Database Adapter in the Registry</title>
<para>
The third way to provide a database adapter to a Table class is by passing a string
in the options array, also identified by the '<property>db</property>' key. The
string is used as a key to the static <classname>Zend_Registry</classname> instance,
where the entry at that key is an object of type
<classname>Zend_Db_Adapter_Abstract</classname>.
</para>
<example id="zend.db.table.constructing.registry.example">
<title>Example of constructing a Table using a Registry key</title>
<programlisting language="php"><![CDATA[
$db = Zend_Db::factory('PDO_MYSQL', $options);
Zend_Registry::set('my_db', $db);
// Later...
$table = new Bugs(array('db' => 'my_db'));
]]></programlisting>
</example>
<para>
Like setting the default adapter, this gives you the means to ensure that the same
adapter instance is used throughout your application. Using the registry is more
flexible, because you can store more than one adapter instance. A given adapter
instance is specific to a certain <acronym>RDBMS</acronym> brand and database
instance. If your application needs access to multiple databases or even multiple
database brands, then you need to use multiple adapters.
</para>
</sect3>
</sect2>
<sect2 id="zend.db.table.insert">
<title>Inserting Rows to a Table</title>
<para>
You can use the Table object to insert rows into the database table on which the Table
object is based. Use the <methodname>insert()</methodname> method of your Table object.
The argument is an associative array, mapping column names to values.
</para>
<example id="zend.db.table.insert.example">
<title>Example of inserting to a Table</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$data = array(
'created_on' => '2007-03-22',
'bug_description' => 'Something wrong',
'bug_status' => 'NEW'
);
$table->insert($data);
]]></programlisting>
</example>
<para>
By default, the values in your data array are inserted as literal values, using
parameters. If you need them to be treated as <acronym>SQL</acronym> expressions, you
must make sure they are distinct from plain strings. Use an object of type
<classname>Zend_Db_Expr</classname> to do this.
</para>
<example id="zend.db.table.insert.example-expr">
<title>Example of inserting expressions to a Table</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$data = array(
'created_on' => new Zend_Db_Expr('CURDATE()'),
'bug_description' => 'Something wrong',
'bug_status' => 'NEW'
);
]]></programlisting>
</example>
<para>
In the examples of inserting rows above, it is assumed that the table has an
auto-incrementing primary key. This is the default behavior of
<classname>Zend_Db_Table_Abstract</classname>, but there are other types of primary keys
as well. The following sections describe how to support different types of primary keys.
</para>
<sect3 id="zend.db.table.insert.key-auto">
<title>Using a Table with an Auto-incrementing Key</title>
<para>
An auto-incrementing primary key generates a unique integer value for you if you
omit the primary key column from your <acronym>SQL</acronym>
<constant>INSERT</constant> statement.
</para>
<para>
In <classname>Zend_Db_Table_Abstract</classname>, if you define the protected
variable <varname>$_sequence</varname> to be the Boolean value
<constant>TRUE</constant>, then the class assumes that the table has an
auto-incrementing primary key.
</para>
<example id="zend.db.table.insert.key-auto.example">
<title>Example of declaring a Table with auto-incrementing primary key</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
// This is the default in the Zend_Db_Table_Abstract class;
// you do not need to define this.
protected $_sequence = true;
}
]]></programlisting>
</example>
<para>
MySQL, Microsoft <acronym>SQL</acronym> Server, and SQLite are examples of
<acronym>RDBMS</acronym> brands that support auto-incrementing primary keys.
</para>
<para>
PostgreSQL has a <constant>SERIAL</constant> notation that implicitly defines a
sequence based on the table and column name, and uses the sequence to generate key
values for new rows. <acronym>IBM</acronym> <acronym>DB2</acronym> has an
<constant>IDENTITY</constant> notation that works similarly. If you use either of
these notations, treat your <classname>Zend_Db_Table</classname> class as having an
auto-incrementing column with respect to declaring the <varname>$_sequence</varname>
member as <constant>TRUE</constant>.
</para>
</sect3>
<sect3 id="zend.db.table.insert.key-sequence">
<title>Using a Table with a Sequence</title>
<para>
A sequence is a database object that generates a unique value, which can be used
as a primary key value in one or more tables of the database.
</para>
<para>
If you define <varname>$_sequence</varname> to be a string, then
<classname>Zend_Db_Table_Abstract</classname> assumes the string to name a sequence
object in the database. The sequence is invoked to generate a new value, and this
value is used in the <constant>INSERT</constant> operation.
</para>
<example id="zend.db.table.insert.key-sequence.example">
<title>Example of declaring a Table with a sequence</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
protected $_sequence = 'bug_sequence';
}
]]></programlisting>
</example>
<para>
Oracle, PostgreSQL, and <acronym>IBM</acronym> <acronym>DB2</acronym> are examples
of <acronym>RDBMS</acronym> brands that support sequence objects in the database.
</para>
<para>
PostgreSQL and <acronym>IBM</acronym> <acronym>DB2</acronym> also have syntax that
defines sequences implicitly and associated with columns. If you use this notation,
treat the table as having an auto-incrementing key column. Define the sequence name
as a string only in cases where you would invoke the sequence explicitly to get the
next key value.
</para>
</sect3>
<sect3 id="zend.db.table.insert.key-natural">
<title>Using a Table with a Natural Key</title>
<para>
Some tables have a natural key. This means that the key is not automatically
generated by the table or by a sequence. You must specify the value for the primary
key in this case.
</para>
<para>
If you define the <varname>$_sequence</varname> to be the Boolean value
<constant>FALSE</constant>, then <classname>Zend_Db_Table_Abstract</classname>
assumes that the table has a natural primary key. You must provide values for the
primary key columns in the array of data to the <methodname>insert()</methodname>
method, or else this method throws a <classname>Zend_Db_Table_Exception</classname>.
</para>
<example id="zend.db.table.insert.key-natural.example">
<title>Example of declaring a Table with a natural key</title>
<programlisting language="php"><![CDATA[
class BugStatus extends Zend_Db_Table_Abstract
{
protected $_name = 'bug_status';
protected $_sequence = false;
}
]]></programlisting>
</example>
<note>
<para>
All <acronym>RDBMS</acronym> brands support tables with natural keys. Examples
of tables that are often declared as having natural keys are lookup tables,
intersection tables in many-to-many relationships, or most tables with compound
primary keys.
</para>
</note>
</sect3>
</sect2>
<sect2 id="zend.db.table.update">
<title>Updating Rows in a Table</title>
<para>
You can update rows in a database table using the <methodname>update()</methodname>
method of a Table class. This method takes two arguments: an associative array of
columns to change and new values to assign to these columns; and an
<acronym>SQL</acronym> expression that is used in a <constant>WHERE</constant> clause,
as criteria for the rows to change in the <constant>UPDATE</constant> operation.
</para>
<example id="zend.db.table.update.example">
<title>Example of updating rows in a Table</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$data = array(
'updated_on' => '2007-03-23',
'bug_status' => 'FIXED'
);
$where = $table->getAdapter()->quoteInto('bug_id = ?', 1234);
$table->update($data, $where);
]]></programlisting>
</example>
<para>
Since the table <methodname>update()</methodname> method proxies to the database adapter
<link linkend="zend.db.adapter.write.update"><methodname>update()</methodname></link>
method, the second argument can be an array of <acronym>SQL</acronym> expressions. The
expressions are combined as Boolean terms using an <constant>AND</constant> operator.
</para>
<note>
<para>
The values and identifiers in the <acronym>SQL</acronym> expression are not quoted
for you. If you have values or identifiers that require quoting, you are responsible
for doing this. Use the <methodname>quote()</methodname>,
<methodname>quoteInto()</methodname>, and <methodname>quoteIdentifier()</methodname>
methods of the database adapter.
</para>
</note>
</sect2>
<sect2 id="zend.db.table.delete">
<title>Deleting Rows from a Table</title>
<para>
You can delete rows from a database table using the <methodname>delete()</methodname>
method. This method takes one argument, which is an <acronym>SQL</acronym> expression
that is used in a <constant>WHERE</constant> clause, as criteria for the rows to delete.
</para>
<example id="zend.db.table.delete.example">
<title>Example of deleting rows from a Table</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$where = $table->getAdapter()->quoteInto('bug_id = ?', 1235);
$table->delete($where);
]]></programlisting>
</example>
<para>
Since the table <methodname>delete()</methodname> method proxies to the database adapter
<link linkend="zend.db.adapter.write.delete"><methodname>delete()</methodname></link>
method, the argument can also be an array of <acronym>SQL</acronym> expressions. The
expressions are combined as Boolean terms using an <constant>AND</constant> operator.
</para>
<note>
<para>
The values and identifiers in the <acronym>SQL</acronym> expression are not quoted
for you. If you have values or identifiers that require quoting, you are responsible
for doing this. Use the <methodname>quote()</methodname>,
<methodname>quoteInto()</methodname>, and <methodname>quoteIdentifier()</methodname>
methods of the database adapter.
</para>
</note>
</sect2>
<sect2 id="zend.db.table.find">
<title>Finding Rows by Primary Key</title>
<para>
You can query the database table for rows matching specific values in the primary key,
using the <methodname>find()</methodname> method. The first argument of this method is
either a single value or an array of values to match against the primary key of the
table.
</para>
<example id="zend.db.table.find.example">
<title>Example of finding rows by primary key values</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
// Find a single row
// Returns a Rowset
$rows = $table->find(1234);
// Find multiple rows
// Also returns a Rowset
$rows = $table->find(array(1234, 5678));
]]></programlisting>
</example>
<para>
If you specify a single value, the method returns at most one row, because a primary
key cannot have duplicate values and there is at most one row in the database table
matching the value you specify. If you specify multiple values in an array, the method
returns at most as many rows as the number of distinct values you specify.
</para>
<para>
The <methodname>find()</methodname> method might return fewer rows than the number of
values you specify for the primary key, if some of the values don't match any rows in
the database table. The method even may return zero rows. Because the number of rows
returned is variable, the <methodname>find()</methodname> method returns an object of
type <classname>Zend_Db_Table_Rowset_Abstract</classname>.
</para>
<para>
If the primary key is a compound key, that is, it consists of multiple columns, you can
specify the additional columns as additional arguments to the
<methodname>find()</methodname> method. You must provide as many arguments as the number
of columns in the table's primary key.
</para>
<para>
To find multiple rows from a table with a compound primary key, provide an array for
each of the arguments. All of these arrays must have the same number of elements. The
values in each array are formed into tuples in order; for example, the first element
in all the array arguments define the first compound primary key value, then the second
elements of all the arrays define the second compound primary key value, and so on.
</para>
<example id="zend.db.table.find.example-compound">
<title>Example of finding rows by compound primary key values</title>
<para>
The call to <methodname>find()</methodname> below to match multiple rows can match
two rows in the database. The first row must have primary key value (1234, 'ABC'),
and the second row must have primary key value (5678, 'DEF').
</para>
<programlisting language="php"><![CDATA[
class BugsProducts extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs_products';
protected $_primary = array('bug_id', 'product_id');
}
$table = new BugsProducts();
// Find a single row with a compound primary key
// Returns a Rowset
$rows = $table->find(1234, 'ABC');
// Find multiple rows with compound primary keys
// Also returns a Rowset
$rows = $table->find(array(1234, 5678), array('ABC', 'DEF'));
]]></programlisting>
</example>
</sect2>
<sect2 id="zend.db.table.fetch-all">
<title>Querying for a Set of Rows</title>
<sect3 id="zend.db.table.fetch-all.select">
<title>Select API</title>
<warning>
<para>
The <acronym>API</acronym> for fetch operations has been superseded to allow
a <classname>Zend_Db_Table_Select</classname> object to modify the query.
However, the deprecated usage of the <methodname>fetchRow()</methodname> and
<methodname>fetchAll()</methodname> methods will continue to work without
modification.
</para>
<para>
The following statements are all legal and functionally identical, however
it is recommended to update your code to take advantage of the new usage
where possible.
</para>
<programlisting language="php"><![CDATA[
/**
* Fetching a rowset
*/
$rows = $table->fetchAll(
'bug_status = "NEW"',
'bug_id ASC',
10,
0
);
$rows = $table->fetchAll(
$table->select()
->where('bug_status = ?', 'NEW')
->order('bug_id ASC')
->limit(10, 0)
);
// or with binding
$rows = $table->fetchAll(
$table->select()
->where('bug_status = :status')
->bind(array(':status'=>'NEW')
->order('bug_id ASC')
->limit(10, 0)
);
/**
* Fetching a single row
*/
$row = $table->fetchRow(
'bug_status = "NEW"',
'bug_id ASC'
);
$row = $table->fetchRow(
$table->select()
->where('bug_status = ?', 'NEW')
->order('bug_id ASC')
);
// or with binding
$row = $table->fetchRow(
$table->select()
->where('bug_status = :status')
->bind(array(':status'=>'NEW')
->order('bug_id ASC')
);
]]></programlisting>
</warning>
<para>
The <classname>Zend_Db_Table_Select</classname> object is an extension of the
<classname>Zend_Db_Select</classname> object that applies specific restrictions to
a query. The enhancements and restrictions are:
</para>
<itemizedlist>
<listitem>
<para>
You <emphasis>can</emphasis> elect to return a subset of columns within a
fetchRow or fetchAll query. This can provide optimization benefits where
returning a large set of results for all columns is not desirable.
</para>
</listitem>
<listitem>
<para>
You <emphasis>can</emphasis> specify columns that evaluate expressions from
within the selected table. However this will mean that the returned row or
rowset will be <property>readOnly</property> and cannot be used for
<methodname>save()</methodname> operations. A
<classname>Zend_Db_Table_Row</classname> with
<property>readOnly</property> status will throw an exception if a
<methodname>save()</methodname> operation is attempted.
</para>
</listitem>
<listitem>
<para>
You <emphasis>can</emphasis> allow <constant>JOIN</constant> clauses on a
select to allow multi-table lookups.
</para>
</listitem>
<listitem>
<para>
You <emphasis>can not</emphasis> specify columns from a JOINed tabled to be
returned in a row or rowset. Doing so will trigger a <acronym>PHP</acronym>
error. This was done to ensure the integrity of the
<classname>Zend_Db_Table</classname> is retained. i.e. A
<classname>Zend_Db_Table_Row</classname> should only reference columns
derived from its parent table.
</para>
</listitem>
</itemizedlist>
<example id="zend.db.table.qry.rows.set.simple.usage.example">
<title>Simple usage</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select();
$select->where('bug_status = ?', 'NEW');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<para>
Fluent interfaces are implemented across the component, so this can be rewritten
this in a more abbreviated form.
</para>
<example id="zend.db.table.qry.rows.set.fluent.interface.example">
<title>Example of fluent interface</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$rows =
$table->fetchAll($table->select()->where('bug_status = ?', 'NEW'));
]]></programlisting>
</example>
</sect3>
<sect3 id="zend.db.table.fetch-all.usage">
<title>Fetching a rowset</title>
<para>
You can query for a set of rows using any criteria other than the primary key
values, using the <methodname>fetchAll()</methodname> method of the Table class.
This method returns an object of type
<classname>Zend_Db_Table_Rowset_Abstract</classname>.
</para>
<example id="zend.db.table.qry.rows.set.finding.row.example">
<title>Example of finding rows by an expression</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select()->where('bug_status = ?', 'NEW');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<para>
You may also pass sorting criteria in an <constant>ORDER</constant> BY clause, as
well as count and offset integer values, used to make the query return a specific
subset of rows. These values are used in a <constant>LIMIT</constant> clause, or in
equivalent logic for <acronym>RDBMS</acronym> brands that do not support the
<constant>LIMIT</constant> syntax.
</para>
<example id="zend.db.table.fetch-all.example2">
<title>Example of finding rows by an expression</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$order = 'bug_id';
// Return the 21st through 30th rows
$count = 10;
$offset = 20;
$select = $table->select()->where('bug_status = ?', 'NEW')
->order($order)
->limit($count, $offset);
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<para>
All of the arguments above are optional. If you omit the <constant>ORDER</constant>
clause, the result set includes rows from the table in an unpredictable order. If
no <constant>LIMIT</constant> clause is set, you retrieve every row in the table
that matches the <constant>WHERE</constant> clause.
</para>
</sect3>
<sect3 id="zend.db.table.advanced.usage">
<title>Advanced usage</title>
<para>
For more specific and optimized requests, you may wish to limit the number of
columns returned in a row or rowset. This can be achieved by passing a
<constant>FROM</constant> clause to the select object. The first argument in the
<constant>FROM</constant> clause is identical to that of a
<classname>Zend_Db_Select</classname> object with the addition of being able to pass
an instance of <classname>Zend_Db_Table_Abstract</classname> and have it
automatically determine the table name.
</para>
<example id="zend.db.table.qry.rows.set.retrieving.a.example">
<title>Retrieving specific columns</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select();
$select->from($table, array('bug_id', 'bug_description'))
->where('bug_status = ?', 'NEW');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<important>
<para>
The rowset contains rows that are still 'valid' - they simply contain a
subset of the columns of a table. If a <methodname>save()</methodname>
method is called on a partial row then only the fields available will be
modified.
</para>
</important>
<para>
You can also specify expressions within a <constant>FROM</constant> clause and have
these returned as a readOnly row or rowset. In this example we will return a rows
from the bugs table that show an aggregate of the number of new bugs reported by
individuals. Note the <constant>GROUP</constant> clause. The 'count' column will be
made available to the row for evaluation and can be accessed as if it were part of
the schema.
</para>
<example id="zend.db.table.qry.rows.set.retrieving.b.example">
<title>Retrieving expressions as columns</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select();
$select->from($table,
array('COUNT(reported_by) as `count`', 'reported_by'))
->where('bug_status = ?', 'NEW')
->group('reported_by');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<para>
You can also use a lookup as part of your query to further refine your fetch
operations. In this example the accounts table is queried as part of a search for
all new bugs reported by 'Bob'.
</para>
<example id="zend.db.table.qry.rows.set.refine.example">
<title>Using a lookup table to refine the results of fetchAll()</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
// retrieve with from part set, important when joining
$select = $table->select(Zend_Db_Table::SELECT_WITH_FROM_PART);
$select->setIntegrityCheck(false)
->where('bug_status = ?', 'NEW')
->join('accounts', 'accounts.account_name = bugs.reported_by')
->where('accounts.account_name = ?', 'Bob');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
<para>
The <classname>Zend_Db_Table_Select</classname> is primarily used to constrain and
validate so that it may enforce the criteria for a legal <constant>SELECT</constant>
query. However there may be certain cases where you require the flexibility of the
<classname>Zend_Db_Table_Row</classname> component and do not require a writable or
deletable row. for this specific user case, it is possible to retrieve a row or
rowset by passing a <constant>FALSE</constant> value to
<methodname>setIntegrityCheck()</methodname>. The resulting row or rowset will be
returned as a 'locked' row (meaning the <methodname>save()</methodname>,
<methodname>delete()</methodname> and any field-setting methods will throw an
exception).
</para>
<example id="zend.db.table.qry.rows.set.integrity.example">
<title>
Removing the integrity check on Zend_Db_Table_Select to allow JOINed rows
</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select(Zend_Db_Table::SELECT_WITH_FROM_PART)
->setIntegrityCheck(false);
$select->where('bug_status = ?', 'NEW')
->join('accounts',
'accounts.account_name = bugs.reported_by',
'account_name')
->where('accounts.account_name = ?', 'Bob');
$rows = $table->fetchAll($select);
]]></programlisting>
</example>
</sect3>
</sect2>
<sect2 id="zend.db.table.fetch-row">
<title>Querying for a Single Row</title>
<para>
You can query for a single row using criteria similar to that of the
<methodname>fetchAll()</methodname> method.
</para>
<example id="zend.db.table.fetch-row.example1">
<title>Example of finding a single row by an expression</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$select = $table->select()->where('bug_status = ?', 'NEW')
->order('bug_id');
$row = $table->fetchRow($select);
]]></programlisting>
</example>
<para>
This method returns an object of type <classname>Zend_Db_Table_Row_Abstract</classname>.
If the search criteria you specified match no rows in the database table, then
<methodname>fetchRow()</methodname> returns <acronym>PHP</acronym>'s
<constant>NULL</constant> value.
</para>
</sect2>
<sect2 id="zend.db.table.info">
<title>Retrieving Table Metadata Information</title>
<para>
The <classname>Zend_Db_Table_Abstract</classname> class provides some information about
its metadata. The <methodname>info()</methodname> method returns an array structure with
information about the table, its columns and primary key, and other metadata.
</para>
<example id="zend.db.table.info.example">
<title>Example of getting the table name</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$info = $table->info();
echo "The table name is " . $info['name'] . "\n";
]]></programlisting>
</example>
<para>
The keys of the array returned by the <methodname>info()</methodname> method are
described below:
</para>
<itemizedlist>
<listitem>
<para>
<emphasis>name</emphasis> => the name of the table.
</para>
</listitem>
<listitem>
<para>
<emphasis>cols</emphasis> => an array, naming the columns of
the table.
</para>
</listitem>
<listitem>
<para>
<emphasis>primary</emphasis> => an array, naming the columns in
the primary key.
</para>
</listitem>
<listitem>
<para>
<emphasis>metadata</emphasis> => an associative array, mapping
column names to information about the columns. This is the information returned
by the <methodname>describeTable()</methodname> method.
</para>
</listitem>
<listitem>
<para>
<emphasis>rowClass</emphasis> => the name of the concrete class
used for Row objects returned by methods of this table instance. This defaults
to <classname>Zend_Db_Table_Row</classname>.
</para>
</listitem>
<listitem>
<para>
<emphasis>rowsetClass</emphasis> => the name of the concrete
class used for Rowset objects returned by methods of this table instance. This
defaults to <classname>Zend_Db_Table_Rowset</classname>.
</para>
</listitem>
<listitem>
<para>
<emphasis>referenceMap</emphasis> => an associative array, with
information about references from this table to any parent tables. See
<link linkend="zend.db.table.relationships.defining">this chapter</link>.
</para>
</listitem>
<listitem>
<para>
<emphasis>dependentTables</emphasis> => an array of class names
of tables that reference this table. See
<link linkend="zend.db.table.relationships.defining">this chapter</link>.
</para>
</listitem>
<listitem>
<para>
<emphasis>schema</emphasis> => the name of the schema (or
database or tablespace) for this table.
</para>
</listitem>
</itemizedlist>
</sect2>
<sect2 id="zend.db.table.metadata.caching">
<title>Caching Table Metadata</title>
<para>
By default, <classname>Zend_Db_Table_Abstract</classname> queries the
underlying database for <link linkend="zend.db.table.info">table
metadata</link> whenever that data is needed to perform table
operations. The table object fetches the table metadata from the
database using the adapter's <methodname>describeTable()</methodname> method.
Operations requiring this introspection include:
</para>
<itemizedlist>
<listitem><para><methodname>insert()</methodname></para></listitem>
<listitem><para><methodname>find()</methodname></para></listitem>
<listitem><para><methodname>info()</methodname></para></listitem>
</itemizedlist>
<para>
In some circumstances, particularly when many table objects are instantiated against
the same database table, querying the database for the table metadata for each instance
may be undesirable from a performance standpoint. In such cases, users may benefit by
caching the table metadata retrieved from the database.
</para>
<para>
There are two primary ways in which a user may take advantage of table metadata
caching:
</para>
<itemizedlist>
<listitem>
<para>
<emphasis>Call
<methodname>Zend_Db_Table_Abstract::setDefaultMetadataCache()</methodname></emphasis>
- This allows a developer to once set the default cache object to be used
for all table classes.
</para>
</listitem>
<listitem>
<para>
<emphasis>Configure
<methodname>Zend_Db_Table_Abstract::__construct()</methodname></emphasis> -
This allows a developer to set the cache object to be used for a particular
table class instance.
</para>
</listitem>
</itemizedlist>
<para>
In both cases, the cache specification must be either <constant>NULL</constant> (i.e.,
no cache used) or an instance of
<link linkend="zend.cache.frontends.core"><classname>Zend_Cache_Core</classname></link>.
The methods may be used in conjunction when it is desirable to have both a default
metadata cache and the ability to change the cache for individual table objects.
</para>
<example id="zend.db.table.metadata.caching-default">
<title>Using a Default Metadata Cache for all Table Objects</title>
<para>
The following code demonstrates how to set a default metadata cache to be used for
all table objects:
</para>
<programlisting language="php"><![CDATA[
// First, set up the Cache
$frontendOptions = array(
'automatic_serialization' => true
);
$backendOptions = array(
'cache_dir' => 'cacheDir'
);
$cache = Zend_Cache::factory('Core',
'File',
$frontendOptions,
$backendOptions);
// Next, set the cache to be used with all table objects
Zend_Db_Table_Abstract::setDefaultMetadataCache($cache);
// A table class is also needed
class Bugs extends Zend_Db_Table_Abstract
{
// ...
}
// Each instance of Bugs now uses the default metadata cache
$bugs = new Bugs();
]]></programlisting>
</example>
<example id="zend.db.table.metadata.caching-instance">
<title>Using a Metadata Cache for a Specific Table Object</title>
<para>
The following code demonstrates how to set a metadata cache for a specific table
object instance:
</para>
<programlisting language="php"><![CDATA[
// First, set up the Cache
$frontendOptions = array(
'automatic_serialization' => true
);
$backendOptions = array(
'cache_dir' => 'cacheDir'
);
$cache = Zend_Cache::factory('Core',
'File',
$frontendOptions,
$backendOptions);
// A table class is also needed
class Bugs extends Zend_Db_Table_Abstract
{
// ...
}
// Configure an instance upon instantiation
$bugs = new Bugs(array('metadataCache' => $cache));
]]></programlisting>
</example>
<note>
<title>Automatic Serialization with the Cache Frontend</title>
<para>
Since the information returned from the adapter's
<methodname>describeTable()</methodname> method is an array, ensure that the
<property>automatic_serialization</property> option is set to
<constant>TRUE</constant> for the <classname>Zend_Cache_Core</classname> frontend.
</para>
</note>
<para>
Though the above examples use <classname>Zend_Cache_Backend_File</classname>, developers
may use whatever cache backend is appropriate for the situation. Please see
<link linkend="zend.cache">Zend_Cache</link> for more information.
</para>
<sect3 id="zend.db.table.metadata.caching.hardcoding">
<title>Hardcoding Table Metadata</title>
<para>
To take metadata caching a step further, you can also choose to
hardcode metadata. In this particular case, however, any changes
to the table schema will require a change in your code. As such,
it is only recommended for those who are optimizing for
production usage.
</para>
<para>
The metadata structure is as follows:
</para>
<programlisting language="php"><![CDATA[
protected $_metadata = array(
'<column_name>' => array(
'SCHEMA_NAME' => <string>,
'TABLE_NAME' => <string>,
'COLUMN_NAME' => <string>,
'COLUMN_POSITION' => <int>,
'DATA_TYPE' => <string>,
'DEFAULT' => NULL|<value>,
'NULLABLE' => <bool>,
'LENGTH' => <string - length>,
'SCALE' => NULL|<value>,
'PRECISION' => NULL|<value>,
'UNSIGNED' => NULL|<bool>,
'PRIMARY' => <bool>,
'PRIMARY_POSITION' => <int>,
'IDENTITY' => <bool>,
),
// additional columns...
);
]]></programlisting>
<para>
An easy way to get the appropriate values is to use the metadata
cache, and then to deserialize values stored in the cache.
</para>
<para>
You can disable this optimization by turning of the
<property>metadataCacheInClass</property> flag:
</para>
<programlisting language="php"><![CDATA[
// At instantiation:
$bugs = new Bugs(array('metadataCacheInClass' => false));
// Or later:
$bugs->setMetadataCacheInClass(false);
]]></programlisting>
<para>
The flag is enabled by default, which ensures that the
<varname>$_metadata</varname> array is only populated once per
instance.
</para>
</sect3>
</sect2>
<sect2 id="zend.db.table.extending">
<title>Customizing and Extending a Table Class</title>
<sect3 id="zend.db.table.extending.row-rowset">
<title>Using Custom Row or Rowset Classes</title>
<para>
By default, methods of the Table class return a Rowset in instances of the concrete
class <classname>Zend_Db_Table_Rowset</classname>, and Rowsets contain a collection
of instances of the concrete class <classname>Zend_Db_Table_Row</classname> You can
specify an alternative class to use for either of these, but they must be classes
that extend <classname>Zend_Db_Table_Rowset_Abstract</classname> and
<classname>Zend_Db_Table_Row_Abstract</classname>, respectively.
</para>
<para>
You can specify Row and Rowset classes using the Table constructor's options array,
in keys '<property>rowClass</property>' and '<property>rowsetClass</property>'
respectively. Specify the names of the classes using strings.
</para>
<example id="zend.db.table.extending.row-rowset.example">
<title>Example of specifying the Row and Rowset classes</title>
<programlisting language="php"><![CDATA[
class My_Row extends Zend_Db_Table_Row_Abstract
{
...
}
class My_Rowset extends Zend_Db_Table_Rowset_Abstract
{
...
}
$table = new Bugs(
array(
'rowClass' => 'My_Row',
'rowsetClass' => 'My_Rowset'
)
);
$where = $table->getAdapter()->quoteInto('bug_status = ?', 'NEW')
// Returns an object of type My_Rowset,
// containing an array of objects of type My_Row.
$rows = $table->fetchAll($where);
]]></programlisting>
</example>
<para>
You can change the classes by specifying them with the
<methodname>setRowClass()</methodname> and <methodname>setRowsetClass()</methodname>
methods. This applies to rows and rowsets created subsequently; it does not change
the class of any row or rowset objects you have created previously.
</para>
<example id="zend.db.table.extending.row-rowset.example2">
<title>Example of changing the Row and Rowset classes</title>
<programlisting language="php"><![CDATA[
$table = new Bugs();
$where = $table->getAdapter()->quoteInto('bug_status = ?', 'NEW')
// Returns an object of type Zend_Db_Table_Rowset
// containing an array of objects of type Zend_Db_Table_Row.
$rowsStandard = $table->fetchAll($where);
$table->setRowClass('My_Row');
$table->setRowsetClass('My_Rowset');
// Returns an object of type My_Rowset,
// containing an array of objects of type My_Row.
$rowsCustom = $table->fetchAll($where);
// The $rowsStandard object still exists, and it is unchanged.
]]></programlisting>
</example>
<para>
For more information on the Row and Rowset classes, see
<link linkend="zend.db.table.row">this chapter</link> and <link
linkend="zend.db.table.rowset">this one</link>.
</para>
</sect3>
<sect3 id="zend.db.table.extending.insert-update">
<title>Defining Custom Logic for Insert, Update, and Delete</title>
<para>
You can override the <methodname>insert()</methodname> and
<methodname>update()</methodname> methods in your Table class. This gives you the
opportunity to implement custom code that is executed before performing the database
operation. Be sure to call the parent class method when you are done.
</para>
<example id="zend.db.table.extending.insert-update.example">
<title>Custom logic to manage timestamps</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
public function insert(array $data)
{
// add a timestamp
if (empty($data['created_on'])) {
$data['created_on'] = time();
}
return parent::insert($data);
}
public function update(array $data, $where)
{
// add a timestamp
if (empty($data['updated_on'])) {
$data['updated_on'] = time();
}
return parent::update($data, $where);
}
}
]]></programlisting>
</example>
<para>
You can also override the <methodname>delete()</methodname> method.
</para>
</sect3>
<sect3 id="zend.db.table.extending.finders">
<title>Define Custom Search Methods in Zend_Db_Table</title>
<para>
You can implement custom query methods in your Table class, if you have frequent
need to do queries against this table with specific criteria. Most queries can be
written using <methodname>fetchAll()</methodname>, but this requires that you
duplicate code to form the query conditions if you need to run the query in several
places in your application. Therefore it can be convenient to implement a method in
the Table class to perform frequently-used queries against this table.
</para>
<example id="zend.db.table.extending.finders.example">
<title>Custom method to find bugs by status</title>
<programlisting language="php"><![CDATA[
class Bugs extends Zend_Db_Table_Abstract
{
protected $_name = 'bugs';
public function findByStatus($status)
{
$where = $this->getAdapter()->quoteInto('bug_status = ?', $status);
return $this->fetchAll($where, 'bug_id');
}
}
]]></programlisting>
</example>
</sect3>
<sect3 id="zend.db.table.extending.inflection">
<title>Define Inflection in Zend_Db_Table</title>
<para>
Some people prefer that the table class name match a table name in the
<acronym>RDBMS</acronym> by using a string transformation called
<emphasis>inflection</emphasis>.
</para>
<para>
For example, if your table class name is "BugsProducts", it would
match the physical table in the database called "bugs_products", if
you omit the explicit declaration of the <varname>$_name</varname> class property.
In this inflection mapping, the class name spelled in "CamelCase" format would be
transformed to lower case, and words are separated with an underscore.
</para>
<para>
You can specify the database table name independently from the class name by
declaring the table name with the <varname>$_name</varname> class property in each
of your table classes.
</para>
<para>
<classname>Zend_Db_Table_Abstract</classname> performs no inflection to map the
class name to the table name. If you omit the declaration of
<varname>$_name</varname> in your table class, the class maps to a database table
that matches the spelling of the class name exactly.
</para>
<para>
It is inappropriate to transform identifiers from the database, because this can
lead to ambiguity or make some identifiers inaccessible. Using the
<acronym>SQL</acronym> identifiers exactly as they appear in the database makes
<classname>Zend_Db_Table_Abstract</classname> both simpler and more flexible.
</para>
<para>
If you prefer to use inflection, then you must implement the transformation
yourself, by overriding the <methodname>_setupTableName()</methodname> method in
your Table classes. One way to do this is to define an abstract class that extends
<classname>Zend_Db_Table_Abstract</classname>, and then the rest of your tables
extend your new abstract class.
</para>
<example id="zend.db.table.extending.inflection.example">
<title>Example of an abstract table class that implements inflection</title>
<programlisting language="php"><![CDATA[
abstract class MyAbstractTable extends Zend_Db_Table_Abstract
{
protected function _setupTableName()
{
if (!$this->_name) {
$this->_name = myCustomInflector(get_class($this));
}
parent::_setupTableName();
}
}
class BugsProducts extends MyAbstractTable
{
}
]]></programlisting>
</example>
<para>
You are responsible for writing the functions to perform inflection transformation.
Zend Framework does not provide such a function.
</para>
</sect3>
</sect2>
</sect1>
<!--
vim:se ts=4 sw=4 et:
-->
|