Django - filtering on foreign key properties
I'm trying to filter a table in Django based on the value of a particular field of a ForeignKey
.
For example, I have two models:
class Asset(models.Model):
name = models.TextFie开发者_JAVA百科ld(max_length=150)
project = models.ForeignKey('Project')
class Project(models.Model):
name = models.TextField(max_length=150)
I'd like to filter my asset list based on the name of the associated project.
Currently, I am performing two queries:
project_list = Project.objects.filter(name__contains="Foo")
asset_list = Asset.objects.filter(desc__contains=filter,
project__in=project_list).order_by('desc')
I'm wondering if there is a way to specify this kind of filtering in the main query?
Asset.objects.filter( project__name__contains="Foo" )
This has been possible since the queryset-refactor
branch landed pre-1.0. Ticket 4088 exposed the problem. This should work:
Asset.objects.filter(
desc__contains=filter,
project__name__contains="Foo").order_by("desc")
The Django Many-to-one documentation has this and other examples of following Foreign Keys using the Model API.
student_user = User.objects.get(id=user_id)
available_subjects = Subject.objects.exclude(subject_grade__student__user=student_user) # My ans
enrolled_subjects = SubjectGrade.objects.filter(student__user=student_user)
context.update({'available_subjects': available_subjects, 'student_user': student_user,
'request':request, 'enrolled_subjects': enrolled_subjects})
In my application above, i assume that once a student is enrolled, a subject SubjectGrade instance will be created that contains the subject enrolled and the student himself/herself.
Subject and Student User model is a Foreign Key to the SubjectGrade Model.
In "available_subjects", i excluded all the subjects that are already enrolled by the current student_user by checking all subjectgrade instance that has "student" attribute as the current student_user
PS. Apologies in Advance if you can't still understand because of my explanation. This is the best explanation i Can Provide. Thank you so much
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