django1/django/db/backends/mysql/introspection.py

from django.db.backends import BaseDatabaseIntrospection
from django.utils import six
from MySQLdb import ProgrammingError, OperationalError
from MySQLdb.constants import FIELD_TYPE
import re

foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")

class DatabaseIntrospection(BaseDatabaseIntrospection):
    data_types_reverse = {
        FIELD_TYPE.BLOB: 'TextField',
        FIELD_TYPE.CHAR: 'CharField',
        FIELD_TYPE.DECIMAL: 'DecimalField',
        FIELD_TYPE.NEWDECIMAL: 'DecimalField',
        FIELD_TYPE.DATE: 'DateField',
        FIELD_TYPE.DATETIME: 'DateTimeField',
        FIELD_TYPE.DOUBLE: 'FloatField',
        FIELD_TYPE.FLOAT: 'FloatField',
        FIELD_TYPE.INT24: 'IntegerField',
        FIELD_TYPE.LONG: 'IntegerField',
        FIELD_TYPE.LONGLONG: 'BigIntegerField',
        FIELD_TYPE.SHORT: 'IntegerField',
        FIELD_TYPE.STRING: 'CharField',
        FIELD_TYPE.TIMESTAMP: 'DateTimeField',
        FIELD_TYPE.TINY: 'IntegerField',
        FIELD_TYPE.TINY_BLOB: 'TextField',
        FIELD_TYPE.MEDIUM_BLOB: 'TextField',
        FIELD_TYPE.LONG_BLOB: 'TextField',
        FIELD_TYPE.VAR_STRING: 'CharField',
    }

    def get_table_list(self, cursor):
        "Returns a list of table names in the current database."
        cursor.execute("SHOW TABLES")
        return [row[0] for row in cursor.fetchall()]

    def get_table_description(self, cursor, table_name):
        "Returns a description of the table, with the DB-API cursor.description interface."
        cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
        return cursor.description

    def _name_to_index(self, cursor, table_name):
        """
        Returns a dictionary of {field_name: field_index} for the given table.
        Indexes are 0-based.
        """
        return dict([(d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name))])

    def get_relations(self, cursor, table_name):
        """
        Returns a dictionary of {field_index: (field_index_other_table, other_table)}
        representing all relationships to the given table. Indexes are 0-based.
        """
        my_field_dict = self._name_to_index(cursor, table_name)
        constraints = self.get_key_columns(cursor, table_name)
        relations = {}
        for my_fieldname, other_table, other_field in constraints:
            other_field_index = self._name_to_index(cursor, other_table)[other_field]
            my_field_index = my_field_dict[my_fieldname]
            relations[my_field_index] = (other_field_index, other_table)
        return relations

    def get_key_columns(self, cursor, table_name):
        """
        Returns a list of (column_name, referenced_table_name, referenced_column_name) for all
        key columns in given table.
        """
        key_columns = []
        cursor.execute("""
            SELECT column_name, referenced_table_name, referenced_column_name
            FROM information_schema.key_column_usage
            WHERE table_name = %s
                AND table_schema = DATABASE()
                AND referenced_table_name IS NOT NULL
                AND referenced_column_name IS NOT NULL""", [table_name])
        key_columns.extend(cursor.fetchall())
        return key_columns

    def get_primary_key_column(self, cursor, table_name):
        """
        Returns the name of the primary key column for the given table
        """
        for column in six.iteritems(self.get_indexes(cursor, table_name)):
            if column[1]['primary_key']:
                return column[0]
        return None

    def get_indexes(self, cursor, table_name):
        cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
        # Do a two-pass search for indexes: on first pass check which indexes
        # are multicolumn, on second pass check which single-column indexes
        # are present.
        rows = list(cursor.fetchall())
        multicol_indexes = set()
        for row in rows:
            if row[3] > 1:
                multicol_indexes.add(row[2])
        indexes = {}
        for row in rows:
            if row[2] in multicol_indexes:
                continue
            indexes[row[4]] = {'primary_key': (row[2] == 'PRIMARY'), 'unique': not bool(row[1])}
        return indexes

    def get_constraints(self, cursor, table_name):
        """
        Retrieves any constraints (unique, pk, fk, check) across one or more columns.
        Returns {'cnname': {'columns': set(columns), 'primary_key': bool, 'unique': bool}}
        """
        constraints = {}
        # Loop over the constraint tables, collecting things as constraints
        ifsc_tables = ["constraint_column_usage", "key_column_usage"]
        for ifsc_table in ifsc_tables:
            cursor.execute("""
                SELECT kc.constraint_name, kc.column_name, c.constraint_type
                FROM information_schema.%s AS kc
                JOIN information_schema.table_constraints AS c ON
                    kc.table_schema = c.table_schema AND
                    kc.table_name = c.table_name AND
                    kc.constraint_name = c.constraint_name
                WHERE
                    kc.table_schema = %%s AND
                    kc.table_name = %%s
            """ % ifsc_table, [self.connection.settings_dict['NAME'], table_name])
            for constraint, column, kind in cursor.fetchall():
                # If we're the first column, make the record
                if constraint not in constraints:
                    constraints[constraint] = {
                        "columns": set(),
                        "primary_key": kind.lower() == "primary key",
                        "foreign_key": kind.lower() == "foreign key",
                        "unique": kind.lower() in ["primary key", "unique"],
                    }
                # Record the details
                constraints[constraint]['columns'].add(column)
        return constraints