ModelSerializer: include all fields and all properties of a model [duplicate] - django

Question

I have two models, one with M2M relation and a related name. I want to include all fields in the serializer and the related field.
models.py:
class Pizza(models.Model):
name = models.CharField(max_length=50, unique=True)
toppings = models.ManyToManyField(Topping, null=True, blank=True, related_name='pizzas')
class Topping(models.Model):
name = models.CharField(max_length=50, unique=True)
price = models.IntegerField(default=0)
serializer.py:
class ToppingSerializer(serializers.ModelSerializer):
class Meta:
model = Topping
fields = '__all__'
This works but it doesn't include the related field.
fields = ['name', 'price', 'pizzas']
This works exactly as I want, but what happens when Toppings model has a lot of fields. I want to do something like :
fields = ['__all__', 'pizzas']
This syntax results in an error saying:
Field name __all__ is not valid for model
Is there a way to achieve the wanted behavior? Or the fields must be typed manually when using a related name ?

Answer 1

Like #DanEEStart said, DjangoRestFramework don't have a simple way to extend the 'all' value for fields, because the get_field_names methods seems to be designed to work that way.
But fortunately you can override this method to allow a simple way to include all fields and relations without enumerate a tons of fields.
I override this method like this:
class ToppingSerializer(serializers.ModelSerializer):
class Meta:
model = Topping
fields = '__all__'
extra_fields = ['pizzas']
def get_field_names(self, declared_fields, info):
expanded_fields = super(ToppingSerializer, self).get_field_names(declared_fields, info)
if getattr(self.Meta, 'extra_fields', None):
return expanded_fields + self.Meta.extra_fields
else:
return expanded_fields
Note that this method only change the behaviour of this serializer, and the extra_fields attribute only works on this serializer class.
If you have a tons of serializer like this, you can create a intermediate class to include this get_fields_names method in one place and reuse'em many times. Some like this:
class CustomSerializer(serializers.HyperlinkedModelSerializer):
def get_field_names(self, declared_fields, info):
expanded_fields = super(CustomSerializer, self).get_field_names(declared_fields, info)
if getattr(self.Meta, 'extra_fields', None):
return expanded_fields + self.Meta.extra_fields
else:
return expanded_fields
class ToppingSerializer(CustomSerializer):
class Meta:
model = Topping
fields = '__all__'
extra_fields = ['pizzas']
class AnotherSerializer(CustomSerializer):
class Meta:
model = Post
fields = '__all__'
extra_fields = ['comments']

Answer 2

I just checked the source code of Django Rest Framework.
The behaviour you want seems not to be supported in the Framework.
The fields option must be a list, a tuple or the text __all__.
Here is a snippet of the relevant source code:
ALL_FIELDS = '__all__'
if fields and fields != ALL_FIELDS and not isinstance(fields, (list, tuple)):
raise TypeError(
'The `fields` option must be a list or tuple or "__all__". '
'Got %s.' % type(fields).__name__
)
You cannot add 'all' additionally to the tuple or list with fields...

Answer 3

The fields="__all__" option can work by specifying an additional field manually as per the following examples. This is by far the cleanest solution around for this issue.
Nested Relationships
http://www.django-rest-framework.org/api-guide/relations/#nested-relationships
class TrackSerializer(serializers.ModelSerializer):
class Meta:
model = Track
fields = '__all__'
class AlbumSerializer(serializers.ModelSerializer):
tracks = TrackSerializer(many=True, read_only=True)
class Meta:
model = Album
fields = '__all__'
I would assume this would work for any of the other related field options listed on the same page: http://www.django-rest-framework.org/api-guide/relations/#serializer-relations
Reverse relation example
class TrackSerializer(serializers.ModelSerializer):
album = AlbumSerializer(source='album_id')
class Meta:
model = Track
fields = '__all__'
Note: Created using Django Rest Framework version 3.6.2, subject to change. Please add a comment if any future changes break any examples posted above.

Answer 4

Hi I could achieve the expected result by using Django's _meta API , which seems to be available since Django 1.11. So in my serializer I did:
model = MyModel
fields = [field.name for field in model._meta.fields]
fields.append('any_other_field')
In programming there's always many ways to achieve the same result, but this one above, has really worked for me.
Cheers!

Answer 5

If you are trying to basically just add extra piece of information into the serialized object, you don't need to change the fields part at all. To add a field you do:
class MySerializer(serializers.ModelSerializer):
...
new_field = serializers.SerializerMethodField('new_field_method')
def new_field_method(self, modelPointer_):
return "MY VALUE"
Then you can still use
class Meta:
fields = '__all__'

Answer 6

to include all the fields and the other fields defined in your serializer you can just say exclude = ()
class ToppingSerializer(serializers.HyperlinkedModelSerializer):
pizzas = '<>' #the extra attribute value
class Meta:
model = Topping
exclude = ()
This will list all the field values with the extra argument pizzas

Answer 7

This is how i did it, much more easier
class OperativeForm(forms.ModelForm):
class Meta:
model = Operative
fields = '__all__'
exclude = ('name','objective',)
widgets = {'__all__':'required'}

Answer 8

Building on top of #Wand's wonderful answer:
def build_fields(mdl,extra=[],exclude=[]):
fields = [field.name for field in mdl._meta.fields if field.name not in exclude]
fields += extra
return fields
Usage:
model = User
fields = build_fields(model, ['snippets'], ['password'])
Will return all fields from the User model, with the related field snippets, without the password field.