from collections import namedtuple from MySQLdb.constants import FIELD_TYPE from django.db.backends.base.introspection import ( BaseDatabaseIntrospection, FieldInfo, TableInfo, ) from django.db.models.indexes import Index from django.utils.datastructures import OrderedSet FieldInfo = namedtuple('FieldInfo', FieldInfo._fields + ('extra', 'is_unsigned')) InfoLine = namedtuple('InfoLine', 'col_name data_type max_len num_prec num_scale extra column_default is_unsigned') 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: 'SmallIntegerField', 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_field_type(self, data_type, description): field_type = super().get_field_type(data_type, description) if 'auto_increment' in description.extra: if field_type == 'IntegerField': return 'AutoField' elif field_type == 'BigIntegerField': return 'BigAutoField' if description.is_unsigned: if field_type == 'IntegerField': return 'PositiveIntegerField' elif field_type == 'SmallIntegerField': return 'PositiveSmallIntegerField' return field_type def get_table_list(self, cursor): """Return a list of table and view names in the current database.""" cursor.execute("SHOW FULL TABLES") return [TableInfo(row[0], {'BASE TABLE': 't', 'VIEW': 'v'}.get(row[1])) for row in cursor.fetchall()] def get_table_description(self, cursor, table_name): """ Return a description of the table with the DB-API cursor.description interface." """ # information_schema database gives more accurate results for some figures: # - varchar length returned by cursor.description is an internal length, # not visible length (#5725) # - precision and scale (for decimal fields) (#5014) # - auto_increment is not available in cursor.description cursor.execute(""" SELECT column_name, data_type, character_maximum_length, numeric_precision, numeric_scale, extra, column_default, CASE WHEN column_type LIKE '%% unsigned' THEN 1 ELSE 0 END AS is_unsigned FROM information_schema.columns WHERE table_name = %s AND table_schema = DATABASE()""", [table_name]) field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()} cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name)) def to_int(i): return int(i) if i is not None else i fields = [] for line in cursor.description: info = field_info[line[0]] fields.append(FieldInfo( *line[:3], to_int(info.max_len) or line[3], to_int(info.num_prec) or line[4], to_int(info.num_scale) or line[5], line[6], info.column_default, info.extra, info.is_unsigned, )) return fields def get_sequences(self, cursor, table_name, table_fields=()): for field_info in self.get_table_description(cursor, table_name): if 'auto_increment' in field_info.extra: # MySQL allows only one auto-increment column per table. return [{'table': table_name, 'column': field_info.name}] return [] def get_relations(self, cursor, table_name): """ Return a dictionary of {field_name: (field_name_other_table, other_table)} representing all relationships to the given table. """ constraints = self.get_key_columns(cursor, table_name) relations = {} for my_fieldname, other_table, other_field in constraints: relations[my_fieldname] = (other_field, other_table) return relations def get_key_columns(self, cursor, table_name): """ Return a list of (column_name, referenced_table_name, referenced_column_name) for all key columns in the 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_storage_engine(self, cursor, table_name): """ Retrieve the storage engine for a given table. Return the default storage engine if the table doesn't exist. """ cursor.execute( "SELECT engine " "FROM information_schema.tables " "WHERE table_name = %s", [table_name]) result = cursor.fetchone() if not result: return self.connection.features._mysql_storage_engine return result[0] def get_constraints(self, cursor, table_name): """ Retrieve 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 = DATABASE() AND kc.table_name = %s ORDER BY kc.`ordinal_position` """ cursor.execute(name_query, [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 = DATABASE() AND c.table_name = %s """ cursor.execute(type_query, [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, type_ in [x[:5] + (x[10],) for x in cursor.fetchall()]: if index not in constraints: constraints[index] = { 'columns': OrderedSet(), 'primary_key': False, 'unique': False, 'check': False, 'foreign_key': None, } constraints[index]['index'] = True constraints[index]['type'] = Index.suffix if type_ == 'BTREE' else type_.lower() constraints[index]['columns'].add(column) # Convert the sorted sets to lists for constraint in constraints.values(): constraint['columns'] = list(constraint['columns']) return constraints