app/django/db/backends/mysql/introspection.py
author Sverre Rabbelier <srabbelier@gmail.com>
Tue, 08 Sep 2009 14:56:39 +0200
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Add a view to start conversion tasks
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from django.db.backends import BaseDatabaseIntrospection
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from MySQLdb import ProgrammingError, OperationalError
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from MySQLdb.constants import FIELD_TYPE
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import re
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foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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    data_types_reverse = {
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        FIELD_TYPE.BLOB: 'TextField',
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        FIELD_TYPE.CHAR: 'CharField',
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        FIELD_TYPE.DECIMAL: 'DecimalField',
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        FIELD_TYPE.NEWDECIMAL: 'DecimalField',
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        FIELD_TYPE.DATE: 'DateField',
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        FIELD_TYPE.DATETIME: 'DateTimeField',
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        FIELD_TYPE.DOUBLE: 'FloatField',
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        FIELD_TYPE.FLOAT: 'FloatField',
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        FIELD_TYPE.INT24: 'IntegerField',
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        FIELD_TYPE.LONG: 'IntegerField',
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        FIELD_TYPE.LONGLONG: 'IntegerField',
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        FIELD_TYPE.SHORT: 'IntegerField',
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        FIELD_TYPE.STRING: 'CharField',
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        FIELD_TYPE.TIMESTAMP: 'DateTimeField',
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        FIELD_TYPE.TINY: 'IntegerField',
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        FIELD_TYPE.TINY_BLOB: 'TextField',
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        FIELD_TYPE.MEDIUM_BLOB: 'TextField',
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        FIELD_TYPE.LONG_BLOB: 'TextField',
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        FIELD_TYPE.VAR_STRING: 'CharField',
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    }
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    def get_table_list(self, cursor):
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        "Returns a list of table names in the current database."
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        cursor.execute("SHOW TABLES")
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        return [row[0] for row in cursor.fetchall()]
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    def get_table_description(self, cursor, table_name):
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        "Returns a description of the table, with the DB-API cursor.description interface."
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        cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
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        return cursor.description
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    def _name_to_index(self, cursor, table_name):
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        """
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        Returns a dictionary of {field_name: field_index} for the given table.
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        Indexes are 0-based.
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        """
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        return dict([(d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name))])
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    def get_relations(self, cursor, table_name):
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        """
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        Returns a dictionary of {field_index: (field_index_other_table, other_table)}
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        representing all relationships to the given table. Indexes are 0-based.
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        """
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        my_field_dict = self._name_to_index(cursor, table_name)
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        constraints = []
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        relations = {}
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        try:
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            # This should work for MySQL 5.0.
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            cursor.execute("""
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                SELECT column_name, referenced_table_name, referenced_column_name
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                FROM information_schema.key_column_usage
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                WHERE table_name = %s
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                    AND table_schema = DATABASE()
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                    AND referenced_table_name IS NOT NULL
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                    AND referenced_column_name IS NOT NULL""", [table_name])
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            constraints.extend(cursor.fetchall())
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        except (ProgrammingError, OperationalError):
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            # Fall back to "SHOW CREATE TABLE", for previous MySQL versions.
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            # Go through all constraints and save the equal matches.
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            cursor.execute("SHOW CREATE TABLE %s" % self.connection.ops.quote_name(table_name))
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            for row in cursor.fetchall():
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                pos = 0
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                while True:
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                    match = foreign_key_re.search(row[1], pos)
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                    if match == None:
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                        break
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                    pos = match.end()
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                    constraints.append(match.groups())
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        for my_fieldname, other_table, other_field in constraints:
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            other_field_index = self._name_to_index(cursor, other_table)[other_field]
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            my_field_index = my_field_dict[my_fieldname]
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            relations[my_field_index] = (other_field_index, other_table)
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        return relations
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    def get_indexes(self, cursor, table_name):
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        """
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        Returns a dictionary of fieldname -> infodict for the given table,
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        where each infodict is in the format:
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            {'primary_key': boolean representing whether it's the primary key,
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             'unique': boolean representing whether it's a unique index}
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        """
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        cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
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        indexes = {}
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        for row in cursor.fetchall():
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            indexes[row[4]] = {'primary_key': (row[2] == 'PRIMARY'), 'unique': not bool(row[1])}
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        return indexes
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