serialize model object with related objects to JSON

Question

I am having a Person model to store person details.

class Person(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)    
    birthdate = models.DateField()

also i am having model PersonLogs to store person's activity logs.

class PersonLogs(models.Model):
    person = models.ForeignKey(Person)
    time = models.DateTimeField(auto_now_add=True)

I am using Django Serializer to return Person objects into JSON format as response.

from django.core import serializers
data = serializers.serialize("json", Person.objects.all())

Output :

{
    "model": "store.person",
    "fields": {
        "first_name": "Douglas",
        "last_name": "Adams",
        "birth_date": "1952-03-11",
    }
}

Now i want to return PersonLogs into response JSON.

Expected Output :

{
    "model": "store.person",
    "fields": {
        "first_name": "Douglas",
        "last_name": "Adams",
        "birth_date": "1952-03-11",
        "personlogs": [['2015-06-09 15:42:58.861540'], ['2014-06-09 15:42:58.861540'], [2013-06-09 15:42:58.861540]]
    }
}

I looked into official documentation but i did not get any help. link

Answer 1

It seems that you want to serialize Person with reverse ForeignKey relationship. Django's serializer doesn't support that. You'll have to use Django REST Framework, for e.g., as pointed out in comments by @DanielRoseman.

But if you can compromise, the following solution will work.

class PersonManager(models.Manager):
    def get_by_natural_key(self, first_name, last_name, birthdate):
        return self.get(first_name=first_name, last_name=last_name, birthdate=birthdate)

class Person(models.Model):
   objects = PersonManager()

   # other fields
   ...

Now, instead of serializing Person, you'll have to serialize PersonLogs, which will output this:

{
    "pk": 1,
    "model": "models.PersonLogs",
    "fields": {
        "time": "2015-06-09 15:42:58.861540",
        "person": ["Douglas", "Adams", "1952-03-11"]
    }
}

Answer 2

You can use serialize template.

Give related name to PersonLogs

class PersonLogs(models.Model):
    person = models.ForeignKey(Person,related_name='logs')
    time = models.DateTimeField(auto_now_add=True)

Create serialize templates

logs_template = {
    'fields': [':local'],
}
person_template = {
    'fields' :[':local',':related'],
    'related':{
         'logs':logs_template,
    }
}

Serialize it with below function:

from preserialize.serialize import serialize
finaldata = serialize(data, **person_template)