How to combine select_related() and value()? (2016

问题:

I am asking this question again (it was asked back in 2009),

We know there is a values() method of QuerySet, when there is a foreignkey (author, for example), it result like:

[{ 'author_id':3, ... }, ...]

I want a result like:

[{ 'author':{'name':'dave',...}, ... }, ...]

Has something changed in the newer versions of Django?

I want to convert the query set into a combination of lists and dictionnaries, is it possible?

I will then take this object and place it into a bigger object to serialize it. It is the reason why I don't want to serialize it right away.

回答1:

You can access related fields via values() without the necessity to use select_related() (only these will be fetched without subsequent lookup):

MyModel.objects.values('author__id', 'author__name')

This will return the following structure:

[{'author__id': 1, 'author__name': 'Dave'}, {...}]

If you need it in a nested structure you would have to transform it afterwards.

Note that for M2M relations, this returns one list entry per M2M relation, so probably not a desired effect. But for OneToOne/ForeignKey relations it works just fine.