There may well be a better way to do this, especially since it's been
a good year since I was struggling with this myself. (Very similar
case to yours, different subject matter of course.)
The way I ended up doing it was to use a template tag and some list
comprehensions to whittle things down. E.g.:
questions = Questions.objects.all()
answers = Answers.objects.filter(candidate=my_candidate)
questions_and_answers = [(q, [a for a in answers if a.question = q])
for q in questions]
...which should give you a list of (question, <list of answers>)
tuples.
On Jun 21, 10:00 am, JeffH <holtzma...@gmail.com> wrote:
> To clarify: Each race has a set of questions. The candidate may have
> responded to none, some, or all. The answers are linked to the
> candidate (and to the question). For each candidate, I want to display
> all the questions, with or without answer. The way it works currently,
> only the questions with answers get displayed.
>
> On Jun 21, 8:41 am, Daniel Roseman <dan...@roseman.org.uk> wrote:
>
>
>
> > On Jun 21, 12:51 pm, JeffH <holtzma...@gmail.com> wrote:
>
> > > I have some models that (simplified) look like the following.
>
> > > class Answer(models.Model):
> > > id = models.CharField(max_length=32, primary_key=True)
> > > text = models.TextField(blank=False)
> > > question = models.ForeignKey(Question)
> > > candidate = models.ForeignKey(Candidate)
>
> > > class Question(models.Model):
> > > id = models.CharField(max_length=32, primary_key=True)
> > > text = models.TextField(blank=False)
>
> > > class Candidate(models.Model):
> > > id = models.CharField(max_length=32, primary_key=True)
> > > name = models.CharField(max_length=32, blank=False)
>
> > > class Race(models.Model):
> > > id = models.CharField(max_length=32, primary_key=True)
> > > name = models.CharField(max_length=128, blank=False)
> > > questions = models.ManyToManyField(Question)
> > > candidates = models.ManyToManyField(Candidate)
>
> > > So, a Race has Candidates and Questions, and a Candidate has Answers.
> > > Each answer is associated with a Question and a Candidate. Displaying
> > > the question associated with an answer is easy:
>
> > > # context variable in view
> > > answers = Answer.objects.filter(candidate=candidate)
>
> > > # template code
> > > <table>
> > > {% for answer in answers %}
> > > <tr>
> > > <td>{{answer.question.text}}</td>
> > > <td>{{answer.text}}</td>
> > > </tr>
> > > {% endfor %}
> > > </table>
>
> > > From the point of view of the Candidate, I need to display all the
> > > questions, including the ones without Answers. I know how to to do
> > > this using raw sql and an outer join. How to do it in the orm?
>
> > > Thanks in advance for any ideas.
>
> > > --Jeff
>
> > Not quite enough information here to answer. What are you wanting to
> > join? If you just want to display all the questions, why do you need a
> > join at all?
> > --
> > DR.
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