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
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>
serializer
— SQLAlchemy 0.6.3 Documentation</title>
<link rel="stylesheet" href="../../_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="../../_static/docs.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../../',
VERSION: '0.6.3',
COLLAPSE_MODINDEX: false,
FILE_SUFFIX: '.html'
};
</script>
<script type="text/javascript" src="../../_static/jquery.js"></script>
<script type="text/javascript" src="../../_static/underscore.js"></script>
<script type="text/javascript" src="../../_static/doctools.js"></script>
<script type="text/javascript" src="../../_static/init.js"></script>
<link rel="index" title="Index" href="../../genindex.html" />
<link rel="search" title="Search" href="../../search.html" />
<link rel="top" title="SQLAlchemy 0.6.3 Documentation" href="../../index.html" />
<link rel="up" title="sqlalchemy.ext" href="index.html" />
<link rel="next" title="SqlSoup" href="sqlsoup.html" />
<link rel="prev" title="orderinglist" href="orderinglist.html" />
</head>
<body>
<h1>SQLAlchemy 0.6.3 Documentation</h1>
<div id="search">
Search:
<form class="search" action="../../search.html" method="get">
<input type="text" name="q" size="18" /> <input type="submit" value="Search" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
<div class="versionheader">
Version: <span class="versionnum">0.6.3</span> Last Updated: 07/15/2010 12:35:47
</div>
<div class="clearboth"></div>
<div class="topnav">
<div id="pagecontrol">
<a href="../index.html">API Reference</a>
|
<a href="../../genindex.html">Index</a>
<div class="sourcelink">(<a href="../../_sources/reference/ext/serializer.txt">view source)</div>
</div>
<div class="navbanner">
<a class="totoc" href="../../index.html">Table of Contents</a>
» <a href="../index.html" title="API Reference">API Reference</a>
» <a href="index.html" title="sqlalchemy.ext">sqlalchemy.ext</a>
»
serializer
<div class="prevnext">
Previous:
<a href="orderinglist.html" title="previous chapter">orderinglist</a>
Next:
<a href="sqlsoup.html" title="next chapter">SqlSoup</a>
</div>
<h2>
serializer
</h2>
</div>
<div class="clearboth"></div>
</div>
<div class="document">
<div class="body">
<div class="section" id="serializer">
<h1>serializer<a class="headerlink" href="#serializer" title="Permalink to this headline">¶</a></h1>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">author:</th><td class="field-body">Mike Bayer</td>
</tr>
</tbody>
</table>
<span class="target" id="module-sqlalchemy.ext.serializer"></span><p>Serializer/Deserializer objects for usage with SQLAlchemy query structures,
allowing “contextual” deserialization.</p>
<p>Any SQLAlchemy query structure, either based on sqlalchemy.sql.*
or sqlalchemy.orm.* can be used. The mappers, Tables, Columns, Session
etc. which are referenced by the structure are not persisted in serialized
form, but are instead re-associated with the query structure
when it is deserialized.</p>
<p>Usage is nearly the same as that of the standard Python pickle module:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">sqlalchemy.ext.serializer</span> <span class="kn">import</span> <span class="n">loads</span><span class="p">,</span> <span class="n">dumps</span>
<span class="n">metadata</span> <span class="o">=</span> <span class="n">MetaData</span><span class="p">(</span><span class="n">bind</span><span class="o">=</span><span class="n">some_engine</span><span class="p">)</span>
<span class="n">Session</span> <span class="o">=</span> <span class="n">scoped_session</span><span class="p">(</span><span class="n">sessionmaker</span><span class="p">())</span>
<span class="c"># ... define mappers</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">Session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">MyClass</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">MyClass</span><span class="o">.</span><span class="n">somedata</span><span class="o">==</span><span class="s">'foo'</span><span class="p">)</span><span class="o">.</span><span class="n">order_by</span><span class="p">(</span><span class="n">MyClass</span><span class="o">.</span><span class="n">sortkey</span><span class="p">)</span>
<span class="c"># pickle the query</span>
<span class="n">serialized</span> <span class="o">=</span> <span class="n">dumps</span><span class="p">(</span><span class="n">query</span><span class="p">)</span>
<span class="c"># unpickle. Pass in metadata + scoped_session</span>
<span class="n">query2</span> <span class="o">=</span> <span class="n">loads</span><span class="p">(</span><span class="n">serialized</span><span class="p">,</span> <span class="n">metadata</span><span class="p">,</span> <span class="n">Session</span><span class="p">)</span>
<span class="k">print</span> <span class="n">query2</span><span class="o">.</span><span class="n">all</span><span class="p">()</span></pre></div>
</div>
<p>Similar restrictions as when using raw pickle apply; mapped classes must be
themselves be pickleable, meaning they are importable from a module-level
namespace.</p>
<p>The serializer module is only appropriate for query structures. It is not
needed for:</p>
<ul class="simple">
<li>instances of user-defined classes. These contain no references to engines,
sessions or expression constructs in the typical case and can be serialized directly.</li>
<li>Table metadata that is to be loaded entirely from the serialized structure (i.e. is
not already declared in the application). Regular pickle.loads()/dumps() can
be used to fully dump any <tt class="docutils literal"><span class="pre">MetaData</span></tt> object, typically one which was reflected
from an existing database at some previous point in time. The serializer module
is specifically for the opposite case, where the Table metadata is already present
in memory.</li>
</ul>
<dl class="function">
<dt id="sqlalchemy.ext.serializer.Serializer">
<tt class="descclassname">sqlalchemy.ext.serializer.</tt><tt class="descname">Serializer</tt><big>(</big><em>*args</em>, <em>**kw</em><big>)</big><a class="headerlink" href="#sqlalchemy.ext.serializer.Serializer" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="function">
<dt id="sqlalchemy.ext.serializer.Deserializer">
<tt class="descclassname">sqlalchemy.ext.serializer.</tt><tt class="descname">Deserializer</tt><big>(</big><em>file</em>, <em>metadata=None</em>, <em>scoped_session=None</em>, <em>engine=None</em><big>)</big><a class="headerlink" href="#sqlalchemy.ext.serializer.Deserializer" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="function">
<dt id="sqlalchemy.ext.serializer.dumps">
<tt class="descclassname">sqlalchemy.ext.serializer.</tt><tt class="descname">dumps</tt><big>(</big><em>obj</em>, <em>protocol=0</em><big>)</big><a class="headerlink" href="#sqlalchemy.ext.serializer.dumps" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="function">
<dt id="sqlalchemy.ext.serializer.loads">
<tt class="descclassname">sqlalchemy.ext.serializer.</tt><tt class="descname">loads</tt><big>(</big><em>data</em>, <em>metadata=None</em>, <em>scoped_session=None</em>, <em>engine=None</em><big>)</big><a class="headerlink" href="#sqlalchemy.ext.serializer.loads" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
</div>
</div>
</div>
<div class="bottomnav">
<div class="prevnext">
Previous:
<a href="orderinglist.html" title="previous chapter">orderinglist</a>
Next:
<a href="sqlsoup.html" title="next chapter">SqlSoup</a>
</div>
<div class="doc_copyright">
© Copyright 2007, 2008, 2009, 2010, the SQLAlchemy authors and contributors.
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.0b2+.
</div>
</div>
</body>
</html>
|
