Thursday, January 29, 2015

Re: Best way to get ForeignKey Related Objects?

"answers" seems to be a method on the AudioQuestionPair class, so your call should be:

for answer in pair.answers():
    print answer

and "pair.answers.get.all()" does not make sense sinse "answers" is a method.

If you don't want to use a specific method, you can do this:

answers = pair.answer_set.all()


On Thu, Jan 29, 2015 at 10:51 AM, Tobias Dacoir <falc410@gmail.com> wrote:
I have two Models as shown below. Now when I have a specific AudioQuestionPair and I do something like

print pair.answers



it works just fine. However I can not do:

for answer in pair.answers



Using pair.answers.get.all() does also not work. So I have to do

answers
= Answer.objects.filter(audioQuestionPair=pair)



Isn't there a better way to design this? I can imagine that using objects.filter is more taxing on the database and uses more time than maybe another method?


class AudioQuestionPair(models.Model):
    audioData
= models.ForeignKey(AudioData)
    question
= models.ForeignKey(Question)
    database
= models.ForeignKey(Database)
    votes
= models.PositiveIntegerField(default=0)

   
class Meta:
        verbose_name
= "AudioData-Question Pair"
        verbose_name_plural
= "AudioData-Question Pairs"

   
def answers(self):
       
return Answer.objects.filter(audioQuestionPair=self.pk)

   
def __str__(self):
       
return "Database %s: AudioData %s - Question %s with %s Votes and Answers: %s" % (self.database, self.audioData, self.question, self.votes, self.answers())

"""
 Answer for a specific Audio-Question Pair
 cumulative
"""

class Answer(models.Model):
    body
= models.CharField(max_length=255)
    count
= models.PositiveIntegerField(default=0)
    isGroundtruth
= models.BooleanField(default=False)
    audioQuestionPair
= models.ForeignKey(AudioQuestionPair)

   
class Meta:
        verbose_name
= "Answer to AudioQuestionPair"
        verbose_name_plural
= "Answers to AudioQuestionPairs"

   
def __str__(self):
       
return "%s - %s times" % (self.body, self.count)



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