Commit 52015b96 authored by Anssi Kääriäinen's avatar Anssi Kääriäinen
Browse files

Used simpler queries for m2m clearing when possible. 

Refs #21169
parent 17c3997f

django/db/models/fields/related.py

+21 −15
Original line number Diff line number Diff line
@@ -580,17 +580,20 @@ def create_many_related_manager(superclass, rel): 
            )

        do_not_call_in_templates = True



        def _build_clear_filters(self, qs):

            filters = Q(**{

                self.source_field_name: self.related_val,

                '%s__in' % self.target_field_name: qs

            })



        def _build_remove_filters(self, removed_vals):

            filters = Q(**{self.source_field_name: self.related_val})

            # No need to add a subquery condition if removed_vals is a QuerySet without

            # filters.

            removed_vals_filters = (not isinstance(removed_vals, QuerySet) or

                                    removed_vals._has_filters())

            if removed_vals_filters:

                filters &= Q(**{'%s__in' % self.target_field_name: removed_vals})

            if self.symmetrical:

                filters |= Q(**{

                    self.target_field_name: self.related_val,

                    '%s__in' % self.source_field_name: qs

                })

                symmetrical_filters = Q(**{self.target_field_name: self.related_val})

                if removed_vals_filters:

                    symmetrical_filters &= Q(

                        **{'%s__in' % self.source_field_name: removed_vals})

                filters |= symmetrical_filters

            return filters



        def get_queryset(self):
@@ -654,7 +657,7 @@ def create_many_related_manager(superclass, rel): 
            signals.m2m_changed.send(sender=self.through, action="pre_clear",

                instance=self.instance, reverse=self.reverse,

                model=self.model, pk_set=None, using=db)

            filters = self._build_clear_filters(self.using(db))

            filters = self._build_remove_filters(super(ManyRelatedManager, self).get_queryset().using(db))

            self.through._default_manager.using(db).filter(filters).delete()



            signals.m2m_changed.send(sender=self.through, action="post_clear",
@@ -763,10 +766,13 @@ def create_many_related_manager(superclass, rel): 
            signals.m2m_changed.send(sender=self.through, action="pre_remove",

                instance=self.instance, reverse=self.reverse,

                model=self.model, pk_set=old_ids, using=db)



            old_vals_qs = self.using(db).filter(**{

            target_model_qs = super(ManyRelatedManager, self).get_queryset()

            if target_model_qs._has_filters():

                old_vals = target_model_qs.using(db).filter(**{

                    '%s__in' % self.target_field.related_field.attname: old_ids})

            filters = self._build_clear_filters(old_vals_qs)

            else:

                old_vals = old_ids

            filters = self._build_remove_filters(old_vals)

            self.through._default_manager.using(db).filter(filters).delete()



            signals.m2m_changed.send(sender=self.through, action="post_remove",

django/db/models/query.py

+8 −0
Original line number Diff line number Diff line
@@ -1026,6 +1026,14 @@ class QuerySet(object): 
        # If we have a new hint for an existing key, overwrite with the new value.

        self._hints.update(hints)



    def _has_filters(self):

        """

        Checks if this QuerySet has any filtering going on. Note that this

        isn't equivalent for checking if all objects are present in results,

        for example qs[1:]._has_filters() -> True.

        """

        return self.query.has_filters()





class InstanceCheckMeta(type):

    def __instancecheck__(self, instance):

django/db/models/sql/query.py

+3 −0
Original line number Diff line number Diff line
@@ -430,6 +430,9 @@ class Query(object): 


        return number



    def has_filters(self):

        return self.where or self.having



    def has_results(self, using):

        q = self.clone()

        if not q.distinct: