sanya-dbms/db_manager/db_plugins/connector.py

"""
/***************************************************************************
Name                 : DB Manager
Description          : Database manager plugin for QGIS
Date                 : May 23, 2011
copyright            : (C) 2011 by Giuseppe Sucameli
email                : brush.tyler@gmail.com

 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
"""

from qgis.core import QgsDataSourceUri

from .plugin import DbError, ConnectionError


class DBConnector:

    def __init__(self, uri):
        """Creates a new DB connector
        """

        self.connection = None
        self._uri = uri

    def __del__(self):
        pass  # print "DBConnector.__del__", self._uri.connectionInfo()
        if self.connection is not None:
            self.connection.close()
        self.connection = None

    def uri(self):
        return QgsDataSourceUri(self._uri.uri(False))

    def cancel(self):
        pass

    def publicUri(self):
        publicUri = QgsDataSourceUri.removePassword(self._uri.uri(False))
        return QgsDataSourceUri(publicUri)

    def hasSpatialSupport(self):
        return False

    def canAddGeometryColumn(self, table):
        return self.hasSpatialSupport()

    def canAddSpatialIndex(self, table):
        return self.hasSpatialSupport()

    def hasRasterSupport(self):
        return False

    def hasCustomQuerySupport(self):
        return False

    def hasTableColumnEditingSupport(self):
        return False

    def hasCreateSpatialViewSupport(self):
        return False

    def execution_error_types(self):
        raise Exception("DBConnector.execution_error_types() is an abstract method")

    def connection_error_types(self):
        raise Exception("DBConnector.connection_error_types() is an abstract method")

    def error_types(self):
        return self.connection_error_types() + self.execution_error_types()

    def _execute(self, cursor, sql):
        if cursor is None:
            cursor = self._get_cursor()
        try:
            cursor.execute(sql)

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            # do the rollback to avoid a "current transaction aborted, commands ignored" errors
            self._rollback()
            raise DbError(e, sql)

        return cursor

    def _execute_and_commit(self, sql):
        """ tries to execute and commit some action, on error it rolls back the change """
        self._execute(None, sql)
        self._commit()

    def _get_cursor(self, name=None):
        try:
            if name is not None:
                name = str(name).encode('ascii', 'replace').replace('?', "_")
                self._last_cursor_named_id = 0 if not hasattr(self,
                                                              '_last_cursor_named_id') else self._last_cursor_named_id + 1
                return self.connection.cursor("%s_%d" % (name, self._last_cursor_named_id))

            return self.connection.cursor()

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            # do the rollback to avoid a "current transaction aborted, commands ignored" errors
            self._rollback()
            raise DbError(e)

    def _close_cursor(self, c):
        try:
            if c and not c.closed:
                c.close()

        except self.error_types():
            pass

        return

    def _fetchall(self, c):
        try:
            return c.fetchall()

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            # do the rollback to avoid a "current transaction aborted, commands ignored" errors
            self._rollback()
            raise DbError(e)

    def _fetchone(self, c):
        try:
            return c.fetchone()

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            # do the rollback to avoid a "current transaction aborted, commands ignored" errors
            self._rollback()
            raise DbError(e)

    def _commit(self):
        try:
            self.connection.commit()

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            # do the rollback to avoid a "current transaction aborted, commands ignored" errors
            self._rollback()
            raise DbError(e)

    def _rollback(self):
        try:
            self.connection.rollback()

        except self.connection_error_types() as e:
            raise ConnectionError(e)

        except self.execution_error_types() as e:
            raise DbError(e)

    def _get_cursor_columns(self, c):
        try:
            if c.description:
                return [x[0] for x in c.description]

        except self.connection_error_types() + self.execution_error_types():
            return []

    @classmethod
    def quoteId(self, identifier):
        if hasattr(identifier, '__iter__') and not isinstance(identifier, str):
            return '.'.join(
                self.quoteId(i)
                for i in identifier
                if i is not None and i != ""
            )

        identifier = str(
            identifier) if identifier is not None else ''  # make sure it's python unicode string
        return '"%s"' % identifier.replace('"', '""')

    @classmethod
    def quoteString(self, txt):
        """ make the string safe - replace ' with '' """
        if hasattr(txt, '__iter__') and not isinstance(txt, str):
            return '.'.join(
                self.quoteString(i)
                for i in txt
                if i is not None
            )

        txt = str(txt) if txt is not None else ''  # make sure it's python unicode string
        return "'%s'" % txt.replace("'", "''")

    @classmethod
    def getSchemaTableName(self, table):
        if not hasattr(table, '__iter__') and not isinstance(table, str):
            return (None, table)
        if isinstance(table, str):
            table = table.split('.')
        if len(table) < 2:
            return (None, table[0])
        else:
            return (table[0], table[1])

    @classmethod
    def getSqlDictionary(self):
        """ return a generic SQL dictionary """
        try:
            from ..sql_dictionary import getSqlDictionary

            return getSqlDictionary()
        except ImportError:
            return []

    def getComment(self, tablename, field):
        """Returns the comment for a field"""
        return ''

    def commentTable(self, schema, tablename, comment=None):
        """Comment the table"""
        pass

    def getQueryBuilderDictionary(self):

        return {}