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Editing: cursors.py
"""MySQLdb Cursors This module implements Cursors of various types for MySQLdb. By default, MySQLdb uses the Cursor class. """ import re from ._exceptions import ProgrammingError #: Regular expression for ``Cursor.executemany```. #: executemany only supports simple bulk insert. #: You can use it to load large dataset. RE_INSERT_VALUES = re.compile( "".join( [ r"\s*((?:INSERT|REPLACE)\b.+\bVALUES?\s*)", r"(\(\s*(?:%s|%\(.+\)s)\s*(?:,\s*(?:%s|%\(.+\)s)\s*)*\))", r"(\s*(?:ON DUPLICATE.*)?);?\s*\Z", ] ), re.IGNORECASE | re.DOTALL, ) class BaseCursor: """A base for Cursor classes. Useful attributes: description A tuple of DB API 7-tuples describing the columns in the last executed query; see PEP-249 for details. description_flags Tuple of column flags for last query, one entry per column in the result set. Values correspond to those in MySQLdb.constants.FLAG. See MySQL documentation (C API) for more information. Non-standard extension. arraysize default number of rows fetchmany() will fetch """ #: Max statement size which :meth:`executemany` generates. #: #: Max size of allowed statement is max_allowed_packet - packet_header_size. #: Default value of max_allowed_packet is 1048576. max_stmt_length = 64 * 1024 from ._exceptions import ( MySQLError, Warning, Error, InterfaceError, DatabaseError, DataError, OperationalError, IntegrityError, InternalError, ProgrammingError, NotSupportedError, ) connection = None def __init__(self, connection): self.connection = connection self.description = None self.description_flags = None self.rowcount = 0 self.arraysize = 1 self._executed = None self.lastrowid = None self._result = None self.rownumber = None self._rows = None def _discard(self): self.description = None self.description_flags = None # Django uses some member after __exit__. # So we keep rowcount and lastrowid here. They are cleared in Cursor._query(). # self.rowcount = 0 # self.lastrowid = None self._rows = None self.rownumber = None if self._result: self._result.discard() self._result = None con = self.connection if con is None: return while con.next_result() == 0: # -1 means no more data. con.discard_result() def close(self): """Close the cursor. No further queries will be possible.""" try: if self.connection is None: return self._discard() finally: self.connection = None self._result = None def __enter__(self): return self def __exit__(self, *exc_info): del exc_info self.close() def _check_executed(self): if not self._executed: raise ProgrammingError("execute() first") def nextset(self): """Advance to the next result set. Returns None if there are no more result sets. """ if self._executed: self.fetchall() db = self._get_db() nr = db.next_result() if nr == -1: return None self._do_get_result(db) self._post_get_result() return 1 def _do_get_result(self, db): self._result = result = self._get_result() if result is None: self.description = self.description_flags = None else: self.description = result.describe() self.description_flags = result.field_flags() self.rowcount = db.affected_rows() self.rownumber = 0 self.lastrowid = db.insert_id() def _post_get_result(self): pass def setinputsizes(self, *args): """Does nothing, required by DB API.""" def setoutputsizes(self, *args): """Does nothing, required by DB API.""" def _get_db(self): con = self.connection if con is None: raise ProgrammingError("cursor closed") return con def execute(self, query, args=None): """Execute a query. query -- string, query to execute on server args -- optional sequence or mapping, parameters to use with query. Note: If args is a sequence, then %s must be used as the parameter placeholder in the query. If a mapping is used, %(key)s must be used as the placeholder. Returns integer represents rows affected, if any """ self._discard() mogrified_query = self._mogrify(query, args) assert isinstance(mogrified_query, (bytes, bytearray)) res = self._query(mogrified_query) return res def _mogrify(self, query, args=None): """Return query after binding args.""" db = self._get_db() if isinstance(query, str): query = query.encode(db.encoding) if args is not None: if isinstance(args, dict): nargs = {} for key, item in args.items(): if isinstance(key, str): key = key.encode(db.encoding) nargs[key] = db.literal(item) args = nargs else: args = tuple(map(db.literal, args)) try: query = query % args except TypeError as m: raise ProgrammingError(str(m)) return query def mogrify(self, query, args=None): """Return query after binding args. query -- string, query to mogrify args -- optional sequence or mapping, parameters to use with query. Note: If args is a sequence, then %s must be used as the parameter placeholder in the query. If a mapping is used, %(key)s must be used as the placeholder. Returns string representing query that would be executed by the server """ return self._mogrify(query, args).decode(self._get_db().encoding) def executemany(self, query, args): # type: (str, list) -> int """Execute a multi-row query. :param query: query to execute on server :param args: Sequence of sequences or mappings. It is used as parameter. :return: Number of rows affected, if any. This method improves performance on multiple-row INSERT and REPLACE. Otherwise it is equivalent to looping over args with execute(). """ if not args: return m = RE_INSERT_VALUES.match(query) if m: q_prefix = m.group(1) % () q_values = m.group(2).rstrip() q_postfix = m.group(3) or "" assert q_values[0] == "(" and q_values[-1] == ")" return self._do_execute_many( q_prefix, q_values, q_postfix, args, self.max_stmt_length, self._get_db().encoding, ) self.rowcount = sum(self.execute(query, arg) for arg in args) return self.rowcount def _do_execute_many( self, prefix, values, postfix, args, max_stmt_length, encoding ): if isinstance(prefix, str): prefix = prefix.encode(encoding) if isinstance(values, str): values = values.encode(encoding) if isinstance(postfix, str): postfix = postfix.encode(encoding) sql = bytearray(prefix) args = iter(args) v = self._mogrify(values, next(args)) sql += v rows = 0 for arg in args: v = self._mogrify(values, arg) if len(sql) + len(v) + len(postfix) + 1 > max_stmt_length: rows += self.execute(sql + postfix) sql = bytearray(prefix) else: sql += b"," sql += v rows += self.execute(sql + postfix) self.rowcount = rows return rows def callproc(self, procname, args=()): """Execute stored procedure procname with args procname -- string, name of procedure to execute on server args -- Sequence of parameters to use with procedure Returns the original args. Compatibility warning: PEP-249 specifies that any modified parameters must be returned. This is currently impossible as they are only available by storing them in a server variable and then retrieved by a query. Since stored procedures return zero or more result sets, there is no reliable way to get at OUT or INOUT parameters via callproc. The server variables are named @_procname_n, where procname is the parameter above and n is the position of the parameter (from zero). Once all result sets generated by the procedure have been fetched, you can issue a SELECT @_procname_0, ... query using .execute() to get any OUT or INOUT values. Compatibility warning: The act of calling a stored procedure itself creates an empty result set. This appears after any result sets generated by the procedure. This is non-standard behavior with respect to the DB-API. Be sure to use nextset() to advance through all result sets; otherwise you may get disconnected. """ db = self._get_db() if isinstance(procname, str): procname = procname.encode(db.encoding) if args: fmt = b"@_" + procname + b"_%d=%s" q = b"SET %s" % b",".join( fmt % (index, db.literal(arg)) for index, arg in enumerate(args) ) self._query(q) self.nextset() q = b"CALL %s(%s)" % ( procname, b",".join([b"@_%s_%d" % (procname, i) for i in range(len(args))]), ) self._query(q) return args def _query(self, q): db = self._get_db() self._result = None self.rowcount = None self.lastrowid = None db.query(q) self._do_get_result(db) self._post_get_result() self._executed = q return self.rowcount def _fetch_row(self, size=1): if not self._result: return () return self._result.fetch_row(size, self._fetch_type) def __iter__(self): return iter(self.fetchone, None) Warning = Warning Error = Error InterfaceError = InterfaceError DatabaseError = DatabaseError DataError = DataError OperationalError = OperationalError IntegrityError = IntegrityError InternalError = InternalError ProgrammingError = ProgrammingError NotSupportedError = NotSupportedError class CursorStoreResultMixIn: """This is a MixIn class which causes the entire result set to be stored on the client side, i.e. it uses mysql_store_result(). If the result set can be very large, consider adding a LIMIT clause to your query, or using CursorUseResultMixIn instead.""" def _get_result(self): return self._get_db().store_result() def _post_get_result(self): self._rows = self._fetch_row(0) self._result = None def fetchone(self): """Fetches a single row from the cursor. None indicates that no more rows are available.""" self._check_executed() if self.rownumber >= len(self._rows): return None result = self._rows[self.rownumber] self.rownumber = self.rownumber + 1 return result def fetchmany(self, size=None): """Fetch up to size rows from the cursor. Result set may be smaller than size. If size is not defined, cursor.arraysize is used.""" self._check_executed() end = self.rownumber + (size or self.arraysize) result = self._rows[self.rownumber : end] self.rownumber = min(end, len(self._rows)) return result def fetchall(self): """Fetches all available rows from the cursor.""" self._check_executed() if self.rownumber: result = self._rows[self.rownumber :] else: result = self._rows self.rownumber = len(self._rows) return result def scroll(self, value, mode="relative"): """Scroll the cursor in the result set to a new position according to mode. If mode is 'relative' (default), value is taken as offset to the current position in the result set, if set to 'absolute', value states an absolute target position.""" self._check_executed() if mode == "relative": r = self.rownumber + value elif mode == "absolute": r = value else: raise ProgrammingError("unknown scroll mode %s" % repr(mode)) if r < 0 or r >= len(self._rows): raise IndexError("out of range") self.rownumber = r def __iter__(self): self._check_executed() result = self.rownumber and self._rows[self.rownumber :] or self._rows return iter(result) class CursorUseResultMixIn: """This is a MixIn class which causes the result set to be stored in the server and sent row-by-row to client side, i.e. it uses mysql_use_result(). You MUST retrieve the entire result set and close() the cursor before additional queries can be performed on the connection.""" def _get_result(self): return self._get_db().use_result() def fetchone(self): """Fetches a single row from the cursor.""" self._check_executed() r = self._fetch_row(1) if not r: return None self.rownumber = self.rownumber + 1 return r[0] def fetchmany(self, size=None): """Fetch up to size rows from the cursor. Result set may be smaller than size. If size is not defined, cursor.arraysize is used.""" self._check_executed() r = self._fetch_row(size or self.arraysize) self.rownumber = self.rownumber + len(r) return r def fetchall(self): """Fetches all available rows from the cursor.""" self._check_executed() r = self._fetch_row(0) self.rownumber = self.rownumber + len(r) return r def __iter__(self): return self def next(self): row = self.fetchone() if row is None: raise StopIteration return row __next__ = next class CursorTupleRowsMixIn: """This is a MixIn class that causes all rows to be returned as tuples, which is the standard form required by DB API.""" _fetch_type = 0 class CursorDictRowsMixIn: """This is a MixIn class that causes all rows to be returned as dictionaries. This is a non-standard feature.""" _fetch_type = 1 class Cursor(CursorStoreResultMixIn, CursorTupleRowsMixIn, BaseCursor): """This is the standard Cursor class that returns rows as tuples and stores the result set in the client.""" class DictCursor(CursorStoreResultMixIn, CursorDictRowsMixIn, BaseCursor): """This is a Cursor class that returns rows as dictionaries and stores the result set in the client.""" class SSCursor(CursorUseResultMixIn, CursorTupleRowsMixIn, BaseCursor): """This is a Cursor class that returns rows as tuples and stores the result set in the server.""" class SSDictCursor(CursorUseResultMixIn, CursorDictRowsMixIn, BaseCursor): """This is a Cursor class that returns rows as dictionaries and stores the result set in the server."""
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