#26706: ManyToMany clear doesn't clear the items from the object but deletes from db -------------------------------------+------------------------------------- Reporter: cosmosgenius | Owner: nobody Type: Bug | Status: new Component: Database layer | Version: 1.8 (models, ORM) | Severity: Normal | Resolution: Keywords: manytomany, m2m, | Triage Stage: clear | Unreviewed Has patch: 0 | Needs documentation: 0 Needs tests: 0 | Patch needs improvement: 0 Easy pickings: 0 | UI/UX: 0 -------------------------------------+------------------------------------- Changes (by cosmosgenius):
* status: closed => new * resolution: worksforme => Old description: > {{{ > > class Media(models.Model): > name = models.CharField(max_length=100) > > class Tag(models.Model): > tag = models.CharField(max_length=100) > medias = models.ManyToManyField(Media) > > def __unicode__(self): > return self.tag > }}} > > Assume tag object below already has three items of Media model in medias > which are saved in db. [m1, m2, m3]. > > {{{ > tag = Tag.objects.get(id=1) > tag.medias.clear() > print(tag.medias.all()) > }}} > > The above code prints all the three [m1, m2, m3]. Fetching the tag again > using get and printing givens an empty list "[ ]" New description: {{{ class Media(models.Model): name = models.CharField(max_length=100) class Tag(models.Model): tag = models.CharField(max_length=100) medias = models.ManyToManyField(Media) def __unicode__(self): return self.tag }}} Assume tag object below already has three items of Media model in medias which are saved in db. [m1, m2, m3]. {{{ tag = Tag.objects.get(id=1) tag.medias.clear() print(tag.medias.all()) }}} The above code prints all the three [m1, m2, m3]. Fetching the tag again using get and printing givens an empty list "[ ]" Failing Testcase {{{ class Test(TestCase): def test(self): tag = Tag.objects.create(tag='Tag') tag.medias.create(name='A') tag.medias.create(name='B') tag.medias.create(name='C') tag = Tag.objects.prefetch_related('medias').get(id=1) tag.medias.clear() print(tag.medias.all()) }}} I guess its related to prefetch_related function. -- Comment: {{{ class Test(TestCase): def test(self): tag = Tag.objects.create(tag='Tag') tag.medias.create(name='A') tag.medias.create(name='B') tag.medias.create(name='C') tag = Tag.objects.prefetch_related('medias').get(id=1) tag.medias.clear() print(tag.medias.all()) }}} -- Ticket URL: <https://code.djangoproject.com/ticket/26706#comment:2> Django <https://code.djangoproject.com/> The Web framework for perfectionists with deadlines. -- You received this message because you are subscribed to the Google Groups "Django updates" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-updates+unsubscr...@googlegroups.com. To post to this group, send email to django-updates@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-updates/070.20ac0a493db239631a6013f59d92b93f%40djangoproject.com. For more options, visit https://groups.google.com/d/optout.