CODEWITHSUNDEEP
pythondjango
pythonhmmm
pythonhmmm

Reputation: 923

better way of handling django query

I have the following models.

class Model1(models.Model):
   name = models.CharField()

class Model2(models.Model):
   name = models.CharField()
   model1 = models.ForeignKey(model1)

class Model3(models.Model):
   name = models.CharField()
   model2 = models.ForeignKey(model2)
   flag = models.BooleanField(blank=False)

so my display should be like, Model2.name and Model1.name on the listing page. conditions are: I should only display Model2 instances which at least have one Model3.flag = True

So right now I am getting all the Model2 objects in the list and iterate over Model3. I am not able to properly use select_related() for the model. Can any one help.

thanks.

Upvotes: 0

Views: 77

Answers (1)

okm
okm

Reputation: 23871

Something like:

qs = Model2.objects.filter(model3__flag=True).select_related('model1').distinct()
for m2 in qs:
    print m2.model1.name, m2.name

# only fetch the names, 
# this works if you treat duplicated ('name', 'model1__name') tuples same and show them once.
qs = qs.values('model1__name', 'name')
for x in qs:
    print x['model1__name'], x['name']

Upvotes: 1

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