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PODjango - How to prevent database foreign key constraint creation
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copied!<p>I have a model that is backed by a database view.</p> <pre><code>class OrgCode(models.Model): org_code = models.CharField(db_column=u'code',max_length=15) org_description = models.CharField(max_length=250) org_level_num = models.IntegerField() class Meta: db_table = u'view_FSS_ORG_PROFILE' </code></pre> <p>I need to reference this in another model</p> <pre><code>class AssessmentLocation(models.Model): name = models.CharField(max_length=150) org = models.ForeignKey(OrgCode) </code></pre> <p>I can't run syncdb because foreign key constraints cannot be created referencing a view.</p> <pre><code> u"Foreign key 'FK__main_asse__org__1D114BD1' references object 'view_FSS_ORG_PROFILE' which is not a user table.", None, 0, -214 7217900), None) Command: CREATE TABLE [main_assessmentlocation] ( [id] int IDENTITY (1, 1) NOT NULL PRIMARY KEY, [name] nvarchar(150) NOT NULL, [org] int NOT NULL REFERENCES [view_FSS_ORG_PROFILE] ([id]), ) </code></pre> <p>The workaround is to take out the Meta:db_table pointing to the view and let sync db create the the OrgCode table, then put the Meta:db_table back in after syncdb. </p> <p>Is there a way to prevent the creation of foreign key constraints for certain models or fields?</p> <p><strong>Update:</strong> I added a static method to the related model indicating it's a view</p> <pre><code>class OrgCode(models.Model): org_code = models.CharField(max_length=15) org_description = models.CharField(max_length=250) @staticmethod def is_backend_view(): return True </code></pre> <p>Then overrode DatabaseCreation.sql_for_inline_foreign_key_references in django_mssql creation.py:</p> <pre><code>def sql_for_inline_foreign_key_references(self, field, known_models, style): try: field.rel.to.is_backend_view() return "", False except: return super(DatabaseCreation,self).sql_for_inline_foreign_key_references(field, known_models, style) </code></pre> <p>The generated sql from syncdb leaves out the constraint:</p> <pre><code>CREATE TABLE [main_assessmentlocation] ( [id] int IDENTITY (1, 1) NOT NULL PRIMARY KEY, [name] nvarchar(150) NOT NULL, [org] int, -- NO FK CONSTRAINT ANYMORE -- ); </code></pre> <p>It does involve hacking django_mssql so I'm going to keep on trying, maybe hooking into the django.db.backends.signals.connection_created signal will work...</p>

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