app/django/db/backends/mysql/introspection.py
author Todd Larsen <tlarsen@google.com>
Fri, 18 Jul 2008 18:22:23 +0000
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child 323 ff1a9aa48cfd
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from django.db.backends.mysql.base import DatabaseOperations
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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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quote_name = DatabaseOperations().quote_name
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foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
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def get_table_list(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(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" % quote_name(table_name))
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    return cursor.description
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def _name_to_index(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(get_table_description(cursor, table_name))])
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def get_relations(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 = _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" % 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 = _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(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" % 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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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.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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}