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MySQLdb
cursors.py
"""MySQLdb Cursors This module implements Cursors of various types for MySQLdb. By default, MySQLdb uses the Cursor class. """ from __future__ import print_function, absolute_import from functools import partial import re import sys from MySQLdb.compat import unicode from _mysql_exceptions import ( Warning, Error, InterfaceError, DataError, DatabaseError, OperationalError, IntegrityError, InternalError, NotSupportedError, ProgrammingError) PY2 = sys.version_info[0] == 2 if PY2: text_type = unicode else: text_type = str #: Regular expression for :meth:`Cursor.executemany`. #: executemany only supports simple bulk insert. #: You can use it to load large dataset. RE_INSERT_VALUES = re.compile( r"\s*((?:INSERT|REPLACE)\s.+\sVALUES?\s+)" + r"(\(\s*(?:%s|%\(.+\)s)\s*(?:,\s*(?:%s|%\(.+\)s)\s*)*\))" + r"(\s*(?:ON DUPLICATE.*)?)\Z", re.IGNORECASE | re.DOTALL) class BaseCursor(object): """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 stetement 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 _mysql_exceptions import MySQLError, Warning, Error, InterfaceError, \ DatabaseError, DataError, OperationalError, IntegrityError, \ InternalError, ProgrammingError, NotSupportedError _defer_warnings = False connection = None def __init__(self, connection): self.connection = connection self.description = None self.description_flags = None self.rowcount = -1 self.arraysize = 1 self._executed = None self.lastrowid = None self.messages = [] self.errorhandler = connection.errorhandler self._result = None self._warnings = None self.rownumber = None def close(self): """Close the cursor. No further queries will be possible.""" try: if self.connection is None: return while self.nextset(): pass finally: self.connection = None self.errorhandler = None self._result = None def __enter__(self): return self def __exit__(self, *exc_info): del exc_info self.close() def _ensure_bytes(self, x, encoding=None): if isinstance(x, text_type): x = x.encode(encoding) elif isinstance(x, (tuple, list)): x = type(x)(self._ensure_bytes(v, encoding=encoding) for v in x) return x def _escape_args(self, args, conn): ensure_bytes = partial(self._ensure_bytes, encoding=conn.encoding) if isinstance(args, (tuple, list)): if PY2: args = tuple(map(ensure_bytes, args)) return tuple(conn.literal(arg) for arg in args) elif isinstance(args, dict): if PY2: args = dict((ensure_bytes(key), ensure_bytes(val)) for (key, val) in args.items()) return dict((key, conn.literal(val)) for (key, val) in args.items()) else: # If it's not a dictionary let's try escaping it anyways. # Worst case it will throw a Value error if PY2: args = ensure_bytes(args) return conn.literal(args) def _check_executed(self): if not self._executed: self.errorhandler(self, ProgrammingError, "execute() first") def _warning_check(self): from warnings import warn db = self._get_db() # None => warnings not interrogated for current query yet # 0 => no warnings exists or have been handled already for this query if self._warnings is None: self._warnings = db.warning_count() if self._warnings: # Only propagate warnings for current query once warning_count = self._warnings self._warnings = 0 # When there is next result, fetching warnings cause "command # out of sync" error. if self._result and self._result.has_next: msg = "There are %d MySQL warnings." % (warning_count,) self.messages.append(msg) warn(self.Warning(0, msg), stacklevel=3) return warnings = db.show_warnings() if warnings: # This is done in two loops in case # Warnings are set to raise exceptions. for w in warnings: self.messages.append((self.Warning, w)) for w in warnings: warn(self.Warning(*w[1:3]), stacklevel=3) else: info = db.info() if info: self.messages.append((self.Warning, info)) warn(self.Warning(0, info), stacklevel=3) def nextset(self): """Advance to the next result set. Returns None if there are no more result sets. """ if self._executed: self.fetchall() del self.messages[:] db = self._get_db() nr = db.next_result() if nr == -1: return None self._do_get_result() self._post_get_result() self._warning_check() return 1 def _post_get_result(self): pass def _do_get_result(self): db = self._get_db() self._result = self._get_result() self.rowcount = db.affected_rows() self.rownumber = 0 self.description = self._result and self._result.describe() or None self.description_flags = self._result and self._result.field_flags() or None self.lastrowid = db.insert_id() self._warnings = None 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 """ while self.nextset(): pass db = self._get_db() # NOTE: # Python 2: query should be bytes when executing %. # All unicode in args should be encoded to bytes on Python 2. # Python 3: query should be str (unicode) when executing %. # All bytes in args should be decoded with ascii and surrogateescape on Python 3. # db.literal(obj) always returns str. if PY2 and isinstance(query, unicode): query = query.encode(db.unicode_literal.charset) if args is not None: if isinstance(args, dict): args = dict((key, db.literal(item)) for key, item in args.items()) else: args = tuple(map(db.literal, args)) if not PY2 and isinstance(query, (bytes, bytearray)): query = query.decode(db.unicode_literal.charset) try: query = query % args except TypeError as m: self.errorhandler(self, ProgrammingError, str(m)) if isinstance(query, unicode): query = query.encode(db.unicode_literal.charset, 'surrogateescape') res = None try: res = self._query(query) except Exception: exc, value = sys.exc_info()[:2] self.errorhandler(self, exc, value) self._executed = query if not self._defer_warnings: self._warning_check() return res 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(). """ del self.messages[:] 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): conn = self._get_db() escape = self._escape_args if isinstance(prefix, text_type): prefix = prefix.encode(encoding) if PY2 and isinstance(values, text_type): values = values.encode(encoding) if isinstance(postfix, text_type): postfix = postfix.encode(encoding) sql = bytearray(prefix) args = iter(args) v = values % escape(next(args), conn) if isinstance(v, text_type): if PY2: v = v.encode(encoding) else: v = v.encode(encoding, 'surrogateescape') sql += v rows = 0 for arg in args: v = values % escape(arg, conn) if isinstance(v, text_type): if PY2: v = v.encode(encoding) else: v = v.encode(encoding, 'surrogateescape') 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() for index, arg in enumerate(args): q = "SET @_%s_%d=%s" % (procname, index, db.literal(arg)) if isinstance(q, unicode): q = q.encode(db.unicode_literal.charset, 'surrogateescape') self._query(q) self.nextset() q = "CALL %s(%s)" % (procname, ','.join(['@_%s_%d' % (procname, i) for i in range(len(args))])) if isinstance(q, unicode): q = q.encode(db.unicode_literal.charset, 'surrogateescape') self._query(q) self._executed = q if not self._defer_warnings: self._warning_check() return args def _do_query(self, q): db = self._get_db() self._last_executed = q db.query(q) self._do_get_result() return self.rowcount def _query(self, q): return self._do_query(q) 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(object): """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 _query(self, q): rowcount = self._do_query(q) self._post_get_result() return rowcount 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): """Fetchs 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: self.errorhandler(self, ProgrammingError, "unknown scroll mode %s" % repr(mode)) if r < 0 or r >= len(self._rows): self.errorhandler(self, 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(object): """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.""" _defer_warnings = True 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: self._warning_check() 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) if not r: self._warning_check() return r def fetchall(self): """Fetchs all available rows from the cursor.""" self._check_executed() r = self._fetch_row(0) self.rownumber = self.rownumber + len(r) self._warning_check() 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(object): """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(object): """This is a MixIn class that causes all rows to be returned as dictionaries. This is a non-standard feature.""" _fetch_type = 1 def fetchoneDict(self): """Fetch a single row as a dictionary. Deprecated: Use fetchone() instead. Will be removed in 1.3.""" from warnings import warn warn("fetchoneDict() is non-standard and will be removed in 1.3", DeprecationWarning, 2) return self.fetchone() def fetchmanyDict(self, size=None): """Fetch several rows as a list of dictionaries. Deprecated: Use fetchmany() instead. Will be removed in 1.3.""" from warnings import warn warn("fetchmanyDict() is non-standard and will be removed in 1.3", DeprecationWarning, 2) return self.fetchmany(size) def fetchallDict(self): """Fetch all available rows as a list of dictionaries. Deprecated: Use fetchall() instead. Will be removed in 1.3.""" from warnings import warn warn("fetchallDict() is non-standard and will be removed in 1.3", DeprecationWarning, 2) return self.fetchall() class CursorOldDictRowsMixIn(CursorDictRowsMixIn): """This is a MixIn class that returns rows as dictionaries with the same key convention as the old Mysqldb (MySQLmodule). Don't use this.""" _fetch_type = 2 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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