Return ManyToManyField IDs when querying model in Django 2.1?

问题

I have two very simple models:

class Person(models.Model):
    full_name = models.CharField(max_length=120)

class Event(models.Model):
    event_date = models.DateField()
    short_description = models.CharField(max_length=250)
    people_involved = models.ManyToManyField(
        Person, blank=True, related_name="people_involved"
    )

I want to return all events, including the people_involved.

In views.py, I have the following:

def alljson(request):
    events = Event.objects.values()
    return JsonResponse(list(events), safe=False)

This returns:

[
    {
        "id": 9, 
        "event_date": "2019-01-01", 
        "short_description": "New Year's Party", 
    }, 
...
]

How do I include the people_involved ManyToManyField in this response?

回答1:

You can use model_to_dict like this:

from django.forms.models import model_to_dict

e_list = []
p_list = []
events = Event.objects.all()
for e in events:
    e_list.append(model_to_dict(e, fields=['event_date', 'short_description']))
    for p in e.people_involved.all():
        p_list.append(model_to_dict(p, fields=['full_name']))   
data = {'events': e_list, 'people_involved': p_list}
return JsonResponse(data)

with model_to_dict you an include or exclude a particular field if you want to :)

or

You can use serializers like this:

from django.core import serializers 

data = {}
events = Event.objects.all()
s_events = serializers.serialize("json", events)
data['events'] = s_events
for event in events:
    data['persons'] = serializers.serialize("json", event.people_involved.all())
return JsonResponse(data)

回答2:

One of the possible way or i think is the best possible way to do that is to use django-restframework-serlizers link.

If you don't want to use that, then unfortunately you need to manually generate all the response, there is no way to get them. You can do this like following

def alljson(request):
    events =[] 
    for event in Event.objects.values():
         response = {}
         response['id'] = event.id
         response['short_description'] = event.short_description
         response['event_date'] = event.event_date
         response['people_involved'] = list(event.people_involved.all())
         events.append(response)


    return JsonResponse(events, safe=False)

来源：https://stackoverflow.com/questions/54555815/return-manytomanyfield-ids-when-querying-model-in-django-2-1