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>
>
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