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Fixed #13312 -- Allowed specifying the order of null fields in queries.

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Thanks Mariusz Felisiak for finishing the patch.
This commit is contained in:
Yohann Gabory 2016-07-27 15:17:05 +02:00 • committed by Tim Graham
parent 82fd779af5
commit 47ef8f31f3
5 changed files with 105 additions and 13 deletions
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43
django/db/models/expressions.py
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@ -319,11 +319,11 @@ class BaseExpression(object):
"""
return [e._output_field_or_none for e in self.get_source_expressions()]
def asc(self):
return OrderBy(self)
def asc(self, **kwargs):
return OrderBy(self, **kwargs)
def desc(self):
return OrderBy(self, descending=True)
def desc(self, **kwargs):
return OrderBy(self, descending=True, **kwargs)
def reverse_ordering(self):
return self
@ -462,11 +462,11 @@ class F(Combinable):
def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
return query.resolve_ref(self.name, allow_joins, reuse, summarize)
def asc(self):
return OrderBy(self)
def asc(self, **kwargs):
return OrderBy(self, **kwargs)
def desc(self):
return OrderBy(self, descending=True)
def desc(self, **kwargs):
return OrderBy(self, descending=True, **kwargs)
class Func(Expression):
@ -869,7 +869,11 @@ class Case(Expression):
class OrderBy(BaseExpression):
template = '%(expression)s %(ordering)s'
def __init__(self, expression, descending=False):
def __init__(self, expression, descending=False, nulls_first=False, nulls_last=False):
if nulls_first and nulls_last:
raise ValueError('nulls_first and nulls_last are mutually exclusive')
self.nulls_first = nulls_first
self.nulls_last = nulls_last
self.descending = descending
if not hasattr(expression, 'resolve_expression'):
raise ValueError('expression must be an expression type')
@ -886,6 +890,11 @@ class OrderBy(BaseExpression):
return [self.expression]
def as_sql(self, compiler, connection, template=None, **extra_context):
if not template:
if self.nulls_last:
template = '%s NULLS LAST' % self.template
elif self.nulls_first:
template = '%s NULLS FIRST' % self.template
connection.ops.check_expression_support(self)
expression_sql, params = compiler.compile(self.expression)
placeholders = {
@ -896,6 +905,22 @@ class OrderBy(BaseExpression):
template = template or self.template
return (template % placeholders).rstrip(), params
def as_sqlite(self, compiler, connection):
template = None
if self.nulls_last:
template = '%(expression)s IS NULL, %(expression)s %(ordering)s'
elif self.nulls_first:
template = '%(expression)s IS NOT NULL, %(expression)s %(ordering)s'
return self.as_sql(compiler, connection, template=template)
def as_mysql(self, compiler, connection):
template = None
if self.nulls_last:
template = 'IF(ISNULL(%(expression)s),1,0), %(expression)s %(ordering)s '
elif self.nulls_first:
template = 'IF(ISNULL(%(expression)s),0,1), %(expression)s %(ordering)s '
return self.as_sql(compiler, connection, template=template)
def get_group_by_cols(self):
cols = []
for source in self.get_source_expressions():