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/*
Package sqlite3 provides interface to SQLite3 databases.
This works as a driver for database/sql.
Installation
go get github.com/mattn/go-sqlite3
Supported Types
Currently, go-sqlite3 supports the following data types.
+------------------------------+
|go | sqlite3 |
|----------|-------------------|
|nil | null |
|int | integer |
|int64 | integer |
|float64 | float |
|bool | integer |
|[]byte | blob |
|string | text |
|time.Time | timestamp/datetime|
+------------------------------+
SQLite3 Extension
You can write your own extension module for sqlite3. For example, below is an
extension for a Regexp matcher operation.
#include <pcre.h>
#include <string.h>
#include <stdio.h>
#include <sqlite3ext.h>
SQLITE_EXTENSION_INIT1
static void regexp_func(sqlite3_context *context, int argc, sqlite3_value **argv) {
if (argc >= 2) {
const char *target = (const char *)sqlite3_value_text(argv[1]);
const char *pattern = (const char *)sqlite3_value_text(argv[0]);
const char* errstr = NULL;
int erroff = 0;
int vec[500];
int n, rc;
pcre* re = pcre_compile(pattern, 0, &errstr, &erroff, NULL);
rc = pcre_exec(re, NULL, target, strlen(target), 0, 0, vec, 500);
if (rc <= 0) {
sqlite3_result_error(context, errstr, 0);
return;
}
sqlite3_result_int(context, 1);
}
}
#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_extension_init(sqlite3 *db, char **errmsg,
const sqlite3_api_routines *api) {
SQLITE_EXTENSION_INIT2(api);
return sqlite3_create_function(db, "regexp", 2, SQLITE_UTF8,
(void*)db, regexp_func, NULL, NULL);
}
It needs to be built as a so/dll shared library. And you need to register
the extension module like below.
sql.Register("sqlite3_with_extensions",
&sqlite3.SQLiteDriver{
Extensions: []string{
"sqlite3_mod_regexp",
},
})
Then, you can use this extension.
rows, err := db.Query("select text from mytable where name regexp '^golang'")
Connection Hook
You can hook and inject your code when the connection is established by setting
ConnectHook to get the SQLiteConn.
sql.Register("sqlite3_with_hook_example",
&sqlite3.SQLiteDriver{
ConnectHook: func(conn *sqlite3.SQLiteConn) error {
sqlite3conn = append(sqlite3conn, conn)
return nil
},
})
You can also use database/sql.Conn.Raw (Go >= 1.13):
conn, err := db.Conn(context.Background())
// if err != nil { ... }
defer conn.Close()
err = conn.Raw(func (driverConn interface{}) error {
sqliteConn := driverConn.(*sqlite3.SQLiteConn)
// ... use sqliteConn
})
// if err != nil { ... }
Go SQlite3 Extensions
If you want to register Go functions as SQLite extension functions
you can make a custom driver by calling RegisterFunction from
ConnectHook.
regex = func(re, s string) (bool, error) {
return regexp.MatchString(re, s)
}
sql.Register("sqlite3_extended",
&sqlite3.SQLiteDriver{
ConnectHook: func(conn *sqlite3.SQLiteConn) error {
return conn.RegisterFunc("regexp", regex, true)
},
})
You can then use the custom driver by passing its name to sql.Open.
var i int
conn, err := sql.Open("sqlite3_extended", "./foo.db")
if err != nil {
panic(err)
}
err = db.QueryRow(`SELECT regexp("foo.*", "seafood")`).Scan(&i)
if err != nil {
panic(err)
}
See the documentation of RegisterFunc for more details.
*/
package sqlite3
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