bottle_sqlite.py

'''
Bottle-sqlite is a plugin that integrates SQLite3 with your Bottle
application. It automatically connects to a database at the beginning of a
request, passes the database handle to the route callback and closes the
connection afterwards.

To automatically detect routes that need a database connection, the plugin
searches for route callbacks that require a `db` keyword argument
(configurable) and skips routes that do not. This removes any overhead for
routes that don't need a database connection.

Usage Example::

    import bottle
    from bottle.ext import sqlite

    app = bottle.Bottle()
    plugin = sqlite.Plugin(dbfile='/tmp/test.db')
    app.install(plugin)

    @app.route('/show/:item')
    def show(item, db):
        row = db.execute('SELECT * from items where name=?', item).fetchone()
        if row:
            return template('showitem', page=row)
        return HTTPError(404, "Page not found")
'''

__author__ = "Marcel Hellkamp"
__version__ = '0.1.2'
__license__ = 'MIT'

### CUT HERE (see setup.py)

import sqlite3
import inspect
from bottle import HTTPResponse, HTTPError


class SQLitePlugin(object):
    ''' This plugin passes an sqlite3 database handle to route callbacks
    that accept a `db` keyword argument. If a callback does not expect
    such a parameter, no connection is made. You can override the database
    settings on a per-route basis. '''

    name = 'sqlite'

    def __init__(self, dbfile=':memory:', autocommit=True, dictrows=True,
                 keyword='db'):
         self.dbfile = dbfile
         self.autocommit = autocommit
         self.dictrows = dictrows
         self.keyword = keyword

    def setup(self, app):
        ''' Make sure that other installed plugins don't affect the same
            keyword argument.'''
        for other in app.plugins:
            if not isinstance(other, SQLitePlugin): continue
            if other.keyword == self.keyword:
                raise PluginError("Found another sqlite plugin with "\
                "conflicting settings (non-unique keyword).")

    def apply(self, callback, context):
        # Override global configuration with route-specific values.
        conf = context['config'].get('sqlite') or {}
        dbfile = conf.get('dbfile', self.dbfile)
        autocommit = conf.get('autocommit', self.autocommit)
        dictrows = conf.get('dictrows', self.dictrows)
        keyword = conf.get('keyword', self.keyword)

        # Test if the original callback accepts a 'db' keyword.
        # Ignore it if it does not need a database handle.
        args = inspect.getargspec(context['callback'])[0]
        if keyword not in args:
            return callback

        def wrapper(*args, **kwargs):
            # Connect to the database
            db = sqlite3.connect(dbfile)
            # This enables column access by name: row['column_name']
            if dictrows: db.row_factory = sqlite3.Row
            # Add the connection handle as a keyword argument.
            kwargs[keyword] = db

            try:
                rv = callback(*args, **kwargs)
                if autocommit: db.commit()
            except sqlite3.IntegrityError, e:
                db.rollback()
                raise HTTPError(500, "Database Error", e)
            except HTTPError, e:
                raise
            except HTTPResponse, e:
                if autocommit: db.commit()
                raise
            finally:
                db.close()
            return rv

        # Replace the route callback with the wrapped one.
        return wrapper

Plugin = SQLitePlugin