import re from .base import FIELD_TYPE from django.utils.datastructures import OrderedSet from django.db.backends import BaseDatabaseIntrospection, FieldInfo from django.utils.encoding import force_text 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.TIME: 'TimeField', 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." """ # varchar length returned by cursor.description is an internal length, # not visible length (#5725), use information_schema database to fix this cursor.execute(""" SELECT column_name, character_maximum_length FROM information_schema.columns WHERE table_name = %s AND table_schema = DATABASE() AND character_maximum_length IS NOT NULL""", [table_name]) length_map = dict(cursor.fetchall()) # Also getting precision and scale from information_schema (see #5014) cursor.execute(""" SELECT column_name, numeric_precision, numeric_scale FROM information_schema.columns WHERE table_name = %s AND table_schema = DATABASE() AND data_type='decimal'""", [table_name]) numeric_map = dict((line[0], tuple(int(n) for n in line[1:])) for line in cursor.fetchall()) cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name)) return [FieldInfo(*((force_text(line[0]),) + line[1:3] + (length_map.get(line[0], line[3]),) + numeric_map.get(line[0], line[4:6]) + (line[6],))) for line in 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_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 if row[4] not in indexes: indexes[row[4]] = {'primary_key': False, 'unique': False} # It's possible to have the unique and PK constraints in separate indexes. if row[2] == 'PRIMARY': indexes[row[4]]['primary_key'] = True if not row[1]: indexes[row[4]]['unique'] = True return indexes def get_storage_engine(self, cursor, table_name): """ Retrieves the storage engine for a given table. """ cursor.execute( "SELECT engine " "FROM information_schema.tables " "WHERE table_name = %s", [table_name]) return cursor.fetchone()[0] def get_constraints(self, cursor, table_name): """ Retrieves any constraints or keys (unique, pk, fk, check, index) across one or more columns. """ constraints = {} # Get the actual constraint names and columns name_query = """ SELECT kc.`constraint_name`, kc.`column_name`, kc.`referenced_table_name`, kc.`referenced_column_name` FROM information_schema.key_column_usage AS kc WHERE kc.table_schema = %s AND kc.table_name = %s """ cursor.execute(name_query, [self.connection.settings_dict['NAME'], table_name]) for constraint, column, ref_table, ref_column in cursor.fetchall(): if constraint not in constraints: constraints[constraint] = { 'columns': OrderedSet(), 'primary_key': False, 'unique': False, 'index': False, 'check': False, 'foreign_key': (ref_table, ref_column) if ref_column else None, } constraints[constraint]['columns'].add(column) # Now get the constraint types type_query = """ SELECT c.constraint_name, c.constraint_type FROM information_schema.table_constraints AS c WHERE c.table_schema = %s AND c.table_name = %s """ cursor.execute(type_query, [self.connection.settings_dict['NAME'], table_name]) for constraint, kind in cursor.fetchall(): if kind.lower() == "primary key": constraints[constraint]['primary_key'] = True constraints[constraint]['unique'] = True elif kind.lower() == "unique": constraints[constraint]['unique'] = True # Now add in the indexes cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name)) for table, non_unique, index, colseq, column in [x[:5] for x in cursor.fetchall()]: if index not in constraints: constraints[index] = { 'columns': OrderedSet(), 'primary_key': False, 'unique': False, 'index': True, 'check': False, 'foreign_key': None, } constraints[index]['index'] = True constraints[index]['columns'].add(column) # Convert the sorted sets to lists for constraint in constraints.values(): constraint['columns'] = list(constraint['columns']) return constraints