def _get_field(model, name):
# Create a fake query object so we can easily work out what field
# type we are dealing with
qs = Query(model)
parts = name.split(LOOKUP_SEP)
# The following is borrowed from the innards of Query.add_filter - it strips out __gt, __exact et al.
num_parts = len(parts)
if num_parts > 1 and parts[-1] in QUERY_TERMS:
# Traverse the lookup query to distinguish related fields from
# lookup types.
for counter, field_name in enumerate(parts, 1):
try:
lookup_field = model._meta.get_field(field_name)
except FieldDoesNotExist:
# Not a field. Bail out.
parts.pop()
break
# Unless we're at the end of the list of lookups, let's attempt
# to continue traversing relations.
if counter < num_parts:
try:
model = lookup_field.rel.to
except AttributeError:
# Not a related field. Bail out.
parts.pop()
break
return qs.names_to_path(parts, qs.get_meta(), True, fail_on_missing=False)[1]
def _get_field(model, name):
# Create a fake query object so we can easily work out what field
# type we are dealing with
parts = name.split(LOOKUP_SEP)
# The following is borrowed from the innards of Query.add_filter - it strips out __gt, __exact et al.
num_parts = len(parts)
if num_parts > 1 and parts[-1] in Query.query_terms:
# Traverse the lookup query to distinguish related fields from
# lookup types.
for counter, field_name in enumerate(parts, 1):
try:
lookup_field = model._meta.get_field(field_name)
except FieldDoesNotExist:
# Not a field. Bail out.
parts.pop()
break
# Unless we're at the end of the list of lookups, let's attempt
# to continue traversing relations.
if counter < num_parts:
try:
model = lookup_field.rel.to
except AttributeError:
# Not a related field. Bail out.
parts.pop()
break
qs = Query(model)
return qs.names_to_path(parts, qs.get_meta(), True,
fail_on_missing=False)[1]
def follow_model_field_lookup(model, lookup):
"""
Follow a model lookup `foreignkey__foreignkey__field` in the same
way that Django QuerySet.filter() does, returning the final models.Field.
"""
query = Query(model)
lookup_splitted = lookup.split(LOOKUP_SEP)
_, field, _, _ = query.names_to_path(lookup_splitted, query.get_meta())
return field
def test_names_to_path_field(self):
query = Query(None)
query.add_annotation(Value(True), "value")
path, final_field, targets, names = query.names_to_path(["value"],
opts=None)
self.assertEqual(path, [])
self.assertIsInstance(final_field, BooleanField)
self.assertEqual(len(targets), 1)
self.assertIsInstance(targets[0], BooleanField)
self.assertEqual(names, [])
def test_names_to_path_field_error(self):
query = Query(None)
msg = "Cannot resolve keyword 'nonexistent' into field."
with self.assertRaisesMessage(FieldError, msg):
query.names_to_path(["nonexistent"], opts=None)
