import re from django.db.backends import BaseDatabaseIntrospection, FieldInfo field_size_re = re.compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$') def get_field_size(name): """ Extract the size number from a "varchar(11)" type name """ m = field_size_re.search(name) return int(m.group(1)) if m else None # This light wrapper "fakes" a dictionary interface, because some SQLite data # types include variables in them -- e.g. "varchar(30)" -- and can't be matched # as a simple dictionary lookup. class FlexibleFieldLookupDict(object): # Maps SQL types to Django Field types. Some of the SQL types have multiple # entries here because SQLite allows for anything and doesn't normalize the # field type; it uses whatever was given. base_data_types_reverse = { 'bool': 'BooleanField', 'boolean': 'BooleanField', 'smallint': 'SmallIntegerField', 'smallint unsigned': 'PositiveSmallIntegerField', 'smallinteger': 'SmallIntegerField', 'int': 'IntegerField', 'integer': 'IntegerField', 'bigint': 'BigIntegerField', 'integer unsigned': 'PositiveIntegerField', 'decimal': 'DecimalField', 'real': 'FloatField', 'text': 'TextField', 'char': 'CharField', 'blob': 'BinaryField', 'date': 'DateField', 'datetime': 'DateTimeField', 'time': 'TimeField', } def __getitem__(self, key): key = key.lower() try: return self.base_data_types_reverse[key] except KeyError: size = get_field_size(key) if size is not None: return ('CharField', {'max_length': size}) raise KeyError class DatabaseIntrospection(BaseDatabaseIntrospection): data_types_reverse = FlexibleFieldLookupDict() def get_table_list(self, cursor): "Returns a list of table names in the current database." # Skip the sqlite_sequence system table used for autoincrement key # generation. cursor.execute(""" SELECT name FROM sqlite_master WHERE type in ('table', 'view') AND NOT name='sqlite_sequence' ORDER BY name""") 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." return [FieldInfo(info['name'], info['type'], None, info['size'], None, None, info['null_ok']) for info in self._table_info(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. """ # Dictionary of relations to return relations = {} # Schema for this table cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"]) results = cursor.fetchone()[0].strip() results = results[results.index('(') + 1:results.rindex(')')] # Walk through and look for references to other tables. SQLite doesn't # really have enforced references, but since it echoes out the SQL used # to create the table we can look for REFERENCES statements used there. for field_index, field_desc in enumerate(results.split(',')): field_desc = field_desc.strip() if field_desc.startswith("UNIQUE"): continue m = re.search('references (.*) \(["|](.*)["|]\)', field_desc, re.I) if not m: continue table, column = [s.strip('"') for s in m.groups()] cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s", [table]) result = cursor.fetchall()[0] other_table_results = result[0].strip() li, ri = other_table_results.index('('), other_table_results.rindex(')') other_table_results = other_table_results[li + 1:ri] for other_index, other_desc in enumerate(other_table_results.split(',')): other_desc = other_desc.strip() if other_desc.startswith('UNIQUE'): continue name = other_desc.split(' ', 1)[0].strip('"') if name == column: relations[field_index] = (other_index, table) break 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 = [] # Schema for this table cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"]) results = cursor.fetchone()[0].strip() results = results[results.index('(') + 1:results.rindex(')')] # Walk through and look for references to other tables. SQLite doesn't # really have enforced references, but since it echoes out the SQL used # to create the table we can look for REFERENCES statements used there. for field_index, field_desc in enumerate(results.split(',')): field_desc = field_desc.strip() if field_desc.startswith("UNIQUE"): continue m = re.search('"(.*)".*references (.*) \(["|](.*)["|]\)', field_desc, re.I) if not m: continue # This will append (column_name, referenced_table_name, referenced_column_name) to key_columns key_columns.append(tuple(s.strip('"') for s in m.groups())) return key_columns def get_indexes(self, cursor, table_name): indexes = {} for info in self._table_info(cursor, table_name): if info['pk'] != 0: indexes[info['name']] = {'primary_key': True, 'unique': False} cursor.execute('PRAGMA index_list(%s)' % self.connection.ops.quote_name(table_name)) # seq, name, unique for index, unique in [(field[1], field[2]) for field in cursor.fetchall()]: cursor.execute('PRAGMA index_info(%s)' % self.connection.ops.quote_name(index)) info = cursor.fetchall() # Skip indexes across multiple fields if len(info) != 1: continue name = info[0][2] # seqno, cid, name indexes[name] = {'primary_key': indexes.get(name, {}).get("primary_key", False), 'unique': unique} return indexes def get_primary_key_column(self, cursor, table_name): """ Get the column name of the primary key for the given table. """ # Don't use PRAGMA because that causes issues with some transactions cursor.execute("SELECT sql FROM sqlite_master WHERE tbl_name = %s AND type = %s", [table_name, "table"]) row = cursor.fetchone() if row is None: raise ValueError("Table %s does not exist" % table_name) results = row[0].strip() results = results[results.index('(') + 1:results.rindex(')')] for field_desc in results.split(','): field_desc = field_desc.strip() m = re.search('"(.*)".*PRIMARY KEY( AUTOINCREMENT)?$', field_desc) if m: return m.groups()[0] return None def _table_info(self, cursor, name): cursor.execute('PRAGMA table_info(%s)' % self.connection.ops.quote_name(name)) # cid, name, type, notnull, dflt_value, pk return [{'name': field[1], 'type': field[2], 'size': get_field_size(field[2]), 'null_ok': not field[3], 'pk': field[5] # undocumented } for field in cursor.fetchall()] 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 index info cursor.execute("PRAGMA index_list(%s)" % self.connection.ops.quote_name(table_name)) for number, index, unique in cursor.fetchall(): # Get the index info for that index cursor.execute('PRAGMA index_info(%s)' % self.connection.ops.quote_name(index)) for index_rank, column_rank, column in cursor.fetchall(): if index not in constraints: constraints[index] = { "columns": [], "primary_key": False, "unique": bool(unique), "foreign_key": False, "check": False, "index": True, } constraints[index]['columns'].append(column) # Get the PK pk_column = self.get_primary_key_column(cursor, table_name) if pk_column: # SQLite doesn't actually give a name to the PK constraint, # so we invent one. This is fine, as the SQLite backend never # deletes PK constraints by name, as you can't delete constraints # in SQLite; we remake the table with a new PK instead. constraints["__primary__"] = { "columns": [pk_column], "primary_key": True, "unique": False, # It's not actually a unique constraint. "foreign_key": False, "check": False, "index": False, } return constraints