"""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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