Thanks for the reply Kirby. I understand that the Question's pk is null when you pass in the Question to the Choice constructor. But when you save the Choice, the Question was saved earlier so the Question's pk is not null. But the Choice's question_id attribute (representing the Question's pk) is still null when you save the Choice.
*1. Should the Choice's question_id have been updated to it's current value when saving the Choice?* I read some more about what happens when you save <https://docs.djangoproject.com/en/1.10/ref/models/instances/#what-happens-when-you-save> an object in Django and it seems like the Choice's question_id should be updated when the data is prepared for the db (step 3 from the link). I understand I can override the Choice class's save method to do this (see code below) but it seems like it should be something that is already done by the Django framework. def save(self, *args, **kwargs): self.question_id = self.question.id super(Choice, self).save(*args, **kwargs) *2. Is there a better way to bulk create objects in a one-to-many relationship *(Questions and Choices)*?* My idea (from the code snippet after models.py) was to bulk create the Questions and then bulk create the Choices but this has the problem mentioned above of the Choice's FK (question_id) not being updated even after the Questions were bulk created. On Monday, November 28, 2016 at 6:59:13 AM UTC-5, C. Kirby wrote: > > The reason it isn't working in your first example is because the pk gets > assigned to the object when it is saved to the database. When you supply > question=q to the choice, it is (correctly) getting a pk of null because q > has not been saved. > > On Saturday, November 26, 2016 at 2:56:37 AM UTC+2, Michael Viveros wrote: >> >> I have a Question model and a Choice model where a Question can have many >> Choices so the Choice model has a Foreign Key mapping to a Question. >> >> models.py: >> >> from django.db import models >> >> >> class Question(models.Model): >> text = models.CharField(max_length=200) >> title = models.CharField(max_length=200) >> total_response_count = models.IntegerField() >> topic = models.CharField(max_length=20) >> sequence_num = models.IntegerField() >> select_multiple = models.BooleanField(default=False) >> >> def __str__(self): >> return self.text >> >> >> class Choice(models.Model): >> question = models.ForeignKey(Question, on_delete=models.CASCADE) >> text = models.CharField(max_length=200) >> response_count = models.IntegerField() >> response_percent = models.FloatField() >> >> def __str__(self): >> return self.text >> >> >> I need to parse a csv file containing these models and insert them into a >> database. >> I want to be efficient and bulk create these models instead of having to >> call save() after creating each model. >> I can bulk create the Questions but then when I try to bulk create the >> Choices I get an IntegrityError about the Choice's foreign key id attribute >> ("question_id") violating a not-null constraint. >> After creating the Questions, the Question's id attribute gets updated >> but the Choice's question_id attribute does not get updated and it does not >> get re-evaluated when the Choice is created. >> >> Here's a simplified version of what I want to do: >> from censustest.models import Question,Choice >> >> >> q=Question(text="Q1",title="",topic="",sequence_num=0,total_response_count=0) >> c=Choice(text="C1",response_count=5,response_percent=0.3,question=q) >> print("q.id %s, c.question %s, c.question_id %s" % (q.id, c.question, >> c.question_id)) # None,Q1,None >> Question.objects.bulk_create([q]) >> print("After creating q: q.id %s, c.question %s, c.question_id %s" % ( >> q.id, c.question, c.question_id)) # valid id,Q1,None >> Choice.objects.bulk_create([c]) # ERROR: IntegrityError >> >> Output: >> >> <https://lh3.googleusercontent.com/-FFbndWx_lfU/WDjbHC_0QUI/AAAAAAAACPQ/xnwdyg_mVNM6lS-jytZTN7n0ujR7FzYiwCLcB/s1600/Screen%2BShot%2B2016-11-25%2Bat%2B7.42.20%2BPM.png> >> >> *Is this a bug with Django *(the foreign key id attribute not being >> updated)* or is there a better way to do it?* >> >> An alternative approach I thought of was to assign the Choice's Question >> after creating the Questions and this works. >> from censustest.models import Question,Choice >> >> >> q=Question(text="Q1",title="",topic="",sequence_num=0,total_response_count=0) >> c=Choice(text="C1",response_count=5,response_percent=0.3) >> print("q.id %s" % (q.id)) # None,Q1,None >> Question.objects.bulk_create([q]) >> c.question=q >> print("c.question %s, c.question_id %s" % (c.question, c.question_id)) # >> Q1,valid id >> Choice.objects.bulk_create([c]) # works, no error >> >> Output: >> >> <https://lh3.googleusercontent.com/-pncM3xKl0Gc/WDjboxPCzWI/AAAAAAAACPU/V4I9TczbqnAm6mBnogU-kIVCvWXJ7ebrQCLcB/s1600/Screen%2BShot%2B2016-11-25%2Bat%2B7.43.53%2BPM.png> >> > -- You received this message because you are subscribed to the Google Groups "Django users" group. 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