from copy import copy
from itertools import repeat
import inspect
from django.conf import settings
from django.utils import timezone
from django.utils.functional import cached_property
from django.utils.six.moves import xrange
class RegisterLookupMixin(object):
def _get_lookup(self, lookup_name):
try:
return self.class_lookups[lookup_name]
except KeyError:
# To allow for inheritance, check parent class' class_lookups.
for parent in inspect.getmro(self.__class__):
if 'class_lookups' not in parent.__dict__:
continue
if lookup_name in parent.class_lookups:
return parent.class_lookups[lookup_name]
except AttributeError:
# This class didn't have any class_lookups
pass
return None
def get_lookup(self, lookup_name):
found = self._get_lookup(lookup_name)
if found is None and hasattr(self, 'output_field'):
return self.output_field.get_lookup(lookup_name)
if found is not None and not issubclass(found, Lookup):
return None
return found
def get_transform(self, lookup_name):
found = self._get_lookup(lookup_name)
if found is None and hasattr(self, 'output_field'):
return self.output_field.get_transform(lookup_name)
if found is not None and not issubclass(found, Transform):
return None
return found
@classmethod
def register_lookup(cls, lookup):
if 'class_lookups' not in cls.__dict__:
cls.class_lookups = {}
cls.class_lookups[lookup.lookup_name] = lookup
@classmethod
def _unregister_lookup(cls, lookup):
"""
Removes given lookup from cls lookups. Meant to be used in
tests only.
"""
del cls.class_lookups[lookup.lookup_name]
[docs]class Transform(RegisterLookupMixin):
def __init__(self, lhs, lookups):
self.lhs = lhs
self.init_lookups = lookups[:]
@cached_property
def output_field(self):
return self.lhs.output_field
def relabeled_clone(self, relabels):
return self.__class__(self.lhs.relabeled_clone(relabels))
def get_group_by_cols(self):
return self.lhs.get_group_by_cols()
[docs]class Lookup(RegisterLookupMixin):
lookup_name = None
def __init__(self, lhs, rhs):
self.lhs, self.rhs = lhs, rhs
self.rhs = self.get_prep_lookup()
def get_prep_lookup(self):
return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
def get_db_prep_lookup(self, value, connection):
return (
'%s', self.lhs.output_field.get_db_prep_lookup(
self.lookup_name, value, connection, prepared=True))
[docs] def process_lhs(self, qn, connection, lhs=None):
lhs = lhs or self.lhs
return qn.compile(lhs)
[docs] def process_rhs(self, qn, connection):
value = self.rhs
# Due to historical reasons there are a couple of different
# ways to produce sql here. get_compiler is likely a Query
# instance, _as_sql QuerySet and as_sql just something with
# as_sql. Finally the value can of course be just plain
# Python value.
if hasattr(value, 'get_compiler'):
value = value.get_compiler(connection=connection)
if hasattr(value, 'as_sql'):
sql, params = qn.compile(value)
return '(' + sql + ')', params
if hasattr(value, '_as_sql'):
sql, params = value._as_sql(connection=connection)
return '(' + sql + ')', params
else:
return self.get_db_prep_lookup(value, connection)
def rhs_is_direct_value(self):
return not(
hasattr(self.rhs, 'as_sql') or
hasattr(self.rhs, '_as_sql') or
hasattr(self.rhs, 'get_compiler'))
def relabeled_clone(self, relabels):
new = copy(self)
new.lhs = new.lhs.relabeled_clone(relabels)
if hasattr(new.rhs, 'relabeled_clone'):
new.rhs = new.rhs.relabeled_clone(relabels)
return new
def get_group_by_cols(self):
cols = self.lhs.get_group_by_cols()
if hasattr(self.rhs, 'get_group_by_cols'):
cols.extend(self.rhs.get_group_by_cols())
return cols
def as_sql(self, qn, connection):
raise NotImplementedError
class BuiltinLookup(Lookup):
def process_lhs(self, qn, connection, lhs=None):
lhs_sql, params = super(BuiltinLookup, self).process_lhs(
qn, connection, lhs)
field_internal_type = self.lhs.output_field.get_internal_type()
db_type = self.lhs.output_field.db_type(connection=connection)
lhs_sql = connection.ops.field_cast_sql(
db_type, field_internal_type) % lhs_sql
lhs_sql = connection.ops.lookup_cast(self.lookup_name) % lhs_sql
return lhs_sql, params
def as_sql(self, qn, connection):
lhs_sql, params = self.process_lhs(qn, connection)
rhs_sql, rhs_params = self.process_rhs(qn, connection)
params.extend(rhs_params)
rhs_sql = self.get_rhs_op(connection, rhs_sql)
return '%s %s' % (lhs_sql, rhs_sql), params
def get_rhs_op(self, connection, rhs):
return connection.operators[self.lookup_name] % rhs
default_lookups = {}
class Exact(BuiltinLookup):
lookup_name = 'exact'
default_lookups['exact'] = Exact
class IExact(BuiltinLookup):
lookup_name = 'iexact'
default_lookups['iexact'] = IExact
class Contains(BuiltinLookup):
lookup_name = 'contains'
default_lookups['contains'] = Contains
class IContains(BuiltinLookup):
lookup_name = 'icontains'
default_lookups['icontains'] = IContains
class GreaterThan(BuiltinLookup):
lookup_name = 'gt'
default_lookups['gt'] = GreaterThan
class GreaterThanOrEqual(BuiltinLookup):
lookup_name = 'gte'
default_lookups['gte'] = GreaterThanOrEqual
class LessThan(BuiltinLookup):
lookup_name = 'lt'
default_lookups['lt'] = LessThan
class LessThanOrEqual(BuiltinLookup):
lookup_name = 'lte'
default_lookups['lte'] = LessThanOrEqual
class In(BuiltinLookup):
lookup_name = 'in'
def get_db_prep_lookup(self, value, connection):
params = self.lhs.output_field.get_db_prep_lookup(
self.lookup_name, value, connection, prepared=True)
if not params:
# TODO: check why this leads to circular import
from django.db.models.sql.datastructures import EmptyResultSet
raise EmptyResultSet
placeholder = '(' + ', '.join('%s' for p in params) + ')'
return (placeholder, params)
def get_rhs_op(self, connection, rhs):
return 'IN %s' % rhs
def as_sql(self, qn, connection):
max_in_list_size = connection.ops.max_in_list_size()
if self.rhs_is_direct_value() and (max_in_list_size and
len(self.rhs) > max_in_list_size):
rhs, rhs_params = self.process_rhs(qn, connection)
lhs, lhs_params = self.process_lhs(qn, connection)
in_clause_elements = ['(']
params = []
for offset in xrange(0, len(rhs_params), max_in_list_size):
if offset > 0:
in_clause_elements.append(' OR ')
in_clause_elements.append('%s IN (' % lhs)
params.extend(lhs_params)
group_size = min(len(rhs_params) - offset, max_in_list_size)
param_group = ', '.join(repeat('%s', group_size))
in_clause_elements.append(param_group)
in_clause_elements.append(')')
params.extend(rhs_params[offset: offset + max_in_list_size])
in_clause_elements.append(')')
return ''.join(in_clause_elements), params
else:
return super(In, self).as_sql(qn, connection)
default_lookups['in'] = In
class PatternLookup(BuiltinLookup):
def get_rhs_op(self, connection, rhs):
# Assume we are in startswith. We need to produce SQL like:
# col LIKE %s, ['thevalue%']
# For python values we can (and should) do that directly in Python,
# but if the value is for example reference to other column, then
# we need to add the % pattern match to the lookup by something like
# col LIKE othercol || '%%'
# So, for Python values we don't need any special pattern, but for
# SQL reference values we need the correct pattern added.
value = self.rhs
if (hasattr(value, 'get_compiler') or hasattr(value, 'as_sql')
or hasattr(value, '_as_sql')):
return connection.pattern_ops[self.lookup_name] % rhs
else:
return super(PatternLookup, self).get_rhs_op(connection, rhs)
class StartsWith(PatternLookup):
lookup_name = 'startswith'
default_lookups['startswith'] = StartsWith
class IStartsWith(PatternLookup):
lookup_name = 'istartswith'
default_lookups['istartswith'] = IStartsWith
class EndsWith(BuiltinLookup):
lookup_name = 'endswith'
default_lookups['endswith'] = EndsWith
class IEndsWith(BuiltinLookup):
lookup_name = 'iendswith'
default_lookups['iendswith'] = IEndsWith
class Between(BuiltinLookup):
def get_rhs_op(self, connection, rhs):
return "BETWEEN %s AND %s" % (rhs, rhs)
class Year(Between):
lookup_name = 'year'
default_lookups['year'] = Year
class Range(Between):
lookup_name = 'range'
default_lookups['range'] = Range
class DateLookup(BuiltinLookup):
def process_lhs(self, qn, connection, lhs=None):
from django.db.models import DateTimeField
lhs, params = super(DateLookup, self).process_lhs(qn, connection, lhs)
if isinstance(self.lhs.output_field, DateTimeField):
tzname = timezone.get_current_timezone_name() if settings.USE_TZ else None
sql, tz_params = connection.ops.datetime_extract_sql(self.extract_type, lhs, tzname)
return connection.ops.lookup_cast(self.lookup_name) % sql, tz_params
else:
return connection.ops.date_extract_sql(self.lookup_name, lhs), []
def get_rhs_op(self, connection, rhs):
return '= %s' % rhs
class Month(DateLookup):
lookup_name = 'month'
extract_type = 'month'
default_lookups['month'] = Month
class Day(DateLookup):
lookup_name = 'day'
extract_type = 'day'
default_lookups['day'] = Day
class WeekDay(DateLookup):
lookup_name = 'week_day'
extract_type = 'week_day'
default_lookups['week_day'] = WeekDay
class Hour(DateLookup):
lookup_name = 'hour'
extract_type = 'hour'
default_lookups['hour'] = Hour
class Minute(DateLookup):
lookup_name = 'minute'
extract_type = 'minute'
default_lookups['minute'] = Minute
class Second(DateLookup):
lookup_name = 'second'
extract_type = 'second'
default_lookups['second'] = Second
class IsNull(BuiltinLookup):
lookup_name = 'isnull'
def as_sql(self, qn, connection):
sql, params = qn.compile(self.lhs)
if self.rhs:
return "%s IS NULL" % sql, params
else:
return "%s IS NOT NULL" % sql, params
default_lookups['isnull'] = IsNull
class Search(BuiltinLookup):
lookup_name = 'search'
def as_sql(self, qn, connection):
lhs, lhs_params = self.process_lhs(qn, connection)
rhs, rhs_params = self.process_rhs(qn, connection)
sql_template = connection.ops.fulltext_search_sql(field_name=lhs)
return sql_template, lhs_params + rhs_params
default_lookups['search'] = Search
class Regex(BuiltinLookup):
lookup_name = 'regex'
def as_sql(self, qn, connection):
if self.lookup_name in connection.operators:
return super(Regex, self).as_sql(qn, connection)
else:
lhs, lhs_params = self.process_lhs(qn, connection)
rhs, rhs_params = self.process_rhs(qn, connection)
sql_template = connection.ops.regex_lookup(self.lookup_name)
return sql_template % (lhs, rhs), lhs_params + rhs_params
default_lookups['regex'] = Regex
class IRegex(Regex):
lookup_name = 'iregex'
default_lookups['iregex'] = IRegex
Feb 24, 2017