django1/django/db/backends/utils.py

247 lines
8.2 KiB
Python

import datetime
import decimal
import functools
import hashlib
import logging
from time import time
from django.conf import settings
from django.db.utils import NotSupportedError
from django.utils.encoding import force_bytes
from django.utils.timezone import utc
logger = logging.getLogger('django.db.backends')
class CursorWrapper:
def __init__(self, cursor, db):
self.cursor = cursor
self.db = db
WRAP_ERROR_ATTRS = frozenset(['fetchone', 'fetchmany', 'fetchall', 'nextset'])
def __getattr__(self, attr):
cursor_attr = getattr(self.cursor, attr)
if attr in CursorWrapper.WRAP_ERROR_ATTRS:
return self.db.wrap_database_errors(cursor_attr)
else:
return cursor_attr
def __iter__(self):
with self.db.wrap_database_errors:
yield from self.cursor
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
# Close instead of passing through to avoid backend-specific behavior
# (#17671). Catch errors liberally because errors in cleanup code
# aren't useful.
try:
self.close()
except self.db.Database.Error:
pass
# The following methods cannot be implemented in __getattr__, because the
# code must run when the method is invoked, not just when it is accessed.
def callproc(self, procname, params=None, kparams=None):
# Keyword parameters for callproc aren't supported in PEP 249, but the
# database driver may support them (e.g. cx_Oracle).
if kparams is not None and not self.db.features.supports_callproc_kwargs:
raise NotSupportedError(
'Keyword parameters for callproc are not supported on this '
'database backend.'
)
self.db.validate_no_broken_transaction()
with self.db.wrap_database_errors:
if params is None and kparams is None:
return self.cursor.callproc(procname)
elif kparams is None:
return self.cursor.callproc(procname, params)
else:
params = params or ()
return self.cursor.callproc(procname, params, kparams)
def execute(self, sql, params=None):
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
def executemany(self, sql, param_list):
return self._execute_with_wrappers(sql, param_list, many=True, executor=self._executemany)
def _execute_with_wrappers(self, sql, params, many, executor):
context = {'connection': self.db, 'cursor': self}
for wrapper in reversed(self.db.execute_wrappers):
executor = functools.partial(wrapper, executor)
return executor(sql, params, many, context)
def _execute(self, sql, params, *ignored_wrapper_args):
self.db.validate_no_broken_transaction()
with self.db.wrap_database_errors:
if params is None:
return self.cursor.execute(sql)
else:
return self.cursor.execute(sql, params)
def _executemany(self, sql, param_list, *ignored_wrapper_args):
self.db.validate_no_broken_transaction()
with self.db.wrap_database_errors:
return self.cursor.executemany(sql, param_list)
class CursorDebugWrapper(CursorWrapper):
# XXX callproc isn't instrumented at this time.
def execute(self, sql, params=None):
start = time()
try:
return super().execute(sql, params)
finally:
stop = time()
duration = stop - start
sql = self.db.ops.last_executed_query(self.cursor, sql, params)
self.db.queries_log.append({
'sql': sql,
'time': "%.3f" % duration,
})
logger.debug(
'(%.3f) %s; args=%s', duration, sql, params,
extra={'duration': duration, 'sql': sql, 'params': params}
)
def executemany(self, sql, param_list):
start = time()
try:
return super().executemany(sql, param_list)
finally:
stop = time()
duration = stop - start
try:
times = len(param_list)
except TypeError: # param_list could be an iterator
times = '?'
self.db.queries_log.append({
'sql': '%s times: %s' % (times, sql),
'time': "%.3f" % duration,
})
logger.debug(
'(%.3f) %s; args=%s', duration, sql, param_list,
extra={'duration': duration, 'sql': sql, 'params': param_list}
)
###############################################
# Converters from database (string) to Python #
###############################################
def typecast_date(s):
return datetime.date(*map(int, s.split('-'))) if s else None # return None if s is null
def typecast_time(s): # does NOT store time zone information
if not s:
return None
hour, minutes, seconds = s.split(':')
if '.' in seconds: # check whether seconds have a fractional part
seconds, microseconds = seconds.split('.')
else:
microseconds = '0'
return datetime.time(int(hour), int(minutes), int(seconds), int((microseconds + '000000')[:6]))
def typecast_timestamp(s): # does NOT store time zone information
# "2005-07-29 15:48:00.590358-05"
# "2005-07-29 09:56:00-05"
if not s:
return None
if ' ' not in s:
return typecast_date(s)
d, t = s.split()
# Extract timezone information, if it exists. Currently it's ignored.
if '-' in t:
t, tz = t.split('-', 1)
tz = '-' + tz
elif '+' in t:
t, tz = t.split('+', 1)
tz = '+' + tz
else:
tz = ''
dates = d.split('-')
times = t.split(':')
seconds = times[2]
if '.' in seconds: # check whether seconds have a fractional part
seconds, microseconds = seconds.split('.')
else:
microseconds = '0'
tzinfo = utc if settings.USE_TZ else None
return datetime.datetime(
int(dates[0]), int(dates[1]), int(dates[2]),
int(times[0]), int(times[1]), int(seconds),
int((microseconds + '000000')[:6]), tzinfo
)
###############################################
# Converters from Python to database (string) #
###############################################
def split_identifier(identifier):
"""
Split a SQL identifier into a two element tuple of (namespace, name).
The identifier could be a table, column, or sequence name might be prefixed
by a namespace.
"""
try:
namespace, name = identifier.split('"."')
except ValueError:
namespace, name = '', identifier
return namespace.strip('"'), name.strip('"')
def truncate_name(identifier, length=None, hash_len=4):
"""
Shorten a SQL identifier to a repeatable mangled version with the given
length.
If a quote stripped name contains a namespace, e.g. USERNAME"."TABLE,
truncate the table portion only.
"""
namespace, name = split_identifier(identifier)
if length is None or len(name) <= length:
return identifier
digest = hashlib.md5(force_bytes(name)).hexdigest()[:hash_len]
return '%s%s%s' % ('%s"."' % namespace if namespace else '', name[:length - hash_len], digest)
def format_number(value, max_digits, decimal_places):
"""
Format a number into a string with the requisite number of digits and
decimal places.
"""
if value is None:
return None
context = decimal.getcontext().copy()
if max_digits is not None:
context.prec = max_digits
if decimal_places is not None:
value = value.quantize(decimal.Decimal(1).scaleb(-decimal_places), context=context)
else:
context.traps[decimal.Rounded] = 1
value = context.create_decimal(value)
return "{:f}".format(value)
def strip_quotes(table_name):
"""
Strip quotes off of quoted table names to make them safe for use in index
names, sequence names, etc. For example '"USER"."TABLE"' (an Oracle naming
scheme) becomes 'USER"."TABLE'.
"""
has_quotes = table_name.startswith('"') and table_name.endswith('"')
return table_name[1:-1] if has_quotes else table_name