Question

I have the following models in an app.

Lesson
Student
Evaluation
Parent

Lesson and Student have a m2m relationship through Evaluation.

I have an inline formset which allows me to create evaluation records at the same time I create a new lesson.

I would like to sort the formset before I process it so that I can put all the records that share a common parent record together and carry out some additional tasks when saving the records.

Here’s a simplified example:

EvaluationFormset = inlineformset_factory(Lesson, Evaluation, extra=1, max_num=10)


if request.method == 'POST': 
    form = LessonForm(request.POST, instance=lesson, user=request.user)
    formset = EvaluationFormset(request.POST, instance=lesson)

    if form.is_valid() and formset.is_valid():
        lesson = form.save()
        models = formset.save(commit=False)

        #Before I do this, I need to sort the formset based on evaluation.student.parent.
        #In the loop, I will perform an additional the first record for each parent

        for i in models:
            i.user = request.user
            i.lesson = lesson
            i.save()

Is there any easy way to this in Django?

Any advice appreciated.

Thanks.

Answer 1

Try something like this:

models = list(models) # maybe this can be omitted
models.sort(key=lambda e: e.student.parent)