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BaseQueryWrapper.prefetch_related(): support Prefetch objects

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This commit is contained in:
Laura Klünder 2017-07-13 21:45:57 +02:00
parent 9fff9e5dcb
commit c208e97ff1
1 changed files with 13 additions and 5 deletions
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18
src/c3nav/editor/wrappers.py
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@ -307,6 +307,13 @@ class BaseQueryWrapper(BaseWrapper):
and convert them into Prefetch() objects with custom querysets.
This makes sure that the prefetch also happens on the virtually modified database.
"""
lookups_qs = {tuple(lookup.prefetch_through.split('__')): lookup.queryset for lookup in lookups
if isinstance(lookup, Prefetch) and lookup.queryset}
for qs in lookups_qs.values():
if not isinstance(qs, QuerySetWrapper):
raise TypeError('Prefetch object queryset needs to be wrapped!')
lookups = tuple((lookup.prefetch_through if isinstance(lookup, Prefetch) else lookup) for lookup in lookups)
lookups_splitted = tuple(tuple(lookup.split('__')) for lookup in lookups)
max_depth = max(len(lookup) for lookup in lookups_splitted)
lookups_by_depth = []
@ -314,20 +321,21 @@ class BaseQueryWrapper(BaseWrapper):
lookups_by_depth.append(set(tuple(lookup[:i+1] for lookup in lookups_splitted if len(lookup) > i)))
lookup_models = {(): self._obj.model}
lookup_querysets = {(): self._obj}
lookup_querysets = {(): self.all()}
for depth_lookups in lookups_by_depth:
for lookup in depth_lookups:
model = lookup_models[lookup[:-1]]._meta.get_field(lookup[-1]).related_model
lookup_models[lookup] = model
lookup_querysets[lookup] = self._wrap_model(model).objects.all()._obj
lookup_querysets[lookup] = lookups_qs.get(lookup, self._wrap_model(model).objects.all())
for depth_lookups in reversed(lookups_by_depth):
for lookup in depth_lookups:
qs = self._wrap_queryset(lookup_querysets[lookup], created_pks=False)
qs = lookup_querysets[lookup]
prefetch = Prefetch(lookup[-1], qs)
lookup_querysets[lookup[:-1]] = lookup_querysets[lookup[:-1]].prefetch_related(prefetch)
lower_qs = lookup_querysets[lookup[:-1]]
lower_qs._obj = lower_qs._obj.prefetch_related(prefetch)
return self._wrap_queryset(lookup_querysets[()])
return lookup_querysets[()]
def _clone(self, **kwargs):
clone = self._wrap_queryset(self._obj)