Serializer fields that don't exist in Django REST framework but can be useful in some cases.
All fields were tested and applied in projects with:
python>=3.6Django>=2.0djangorestframework>=3.9
pip install git+https://github.com/VoronaMV/drf-fields.git
This is short documentation about each field.
drf_fields.fields NaturalChoiceField
This field extends rest_framework.serializers.ChoiceField.
The native DRF ChoiceField doesn't return real model or field choices
in representation, especially when representation and internal representation
have different types.
This field make possible to retrieve to_representation choice that defined.
For example, you have models.py file:
from django.db import models
class Person(models.Model):
MALE = 1
FEMALE = 2
SEX_CHOICES = (
(MALE, 'male'),
(FEMALE, 'female'),
)
name = models.CharField(max_length=255)
sex = models.IntegerField(choices=SEX_CHOICES)And serializers.py
from rest_framework import serializers
from drf_fields.fields import NaturalChoiceField
from myapp.models import Person
class PersonSerializerNaturalChoiceField(serializers.ModelSerializer):
sex = NaturalChoiceField(choices=Person.SEX_CHOICES)
class Meta:
model = Person
fields = ('name', 'sex')
class PersonSerializerWithDRFChoiceField(serializers.ModelSerializer):
sex = serializers.ChoiceField(choices=Person.SEX_CHOICES)
class Meta:
model = Person
fields = ('name', 'sex')Creating 2 person objects
In [1]: from myapp.models import Person
In [2]: from myapp.serializers import PersonSerializerNaturalChoiceField, PersonSerializerWithDRFChoiceField
In [3]: bob = Person.objects.create(name='Bob', sex=Person.MALE)
In [4]: ann = Person.objects.create(name='Ann', sex=Person.FEMALE)
Check that DB values really saved as numeric
In [5]: bob.sex, ann.sex
Out[5]: (1, 2)
What returns native DRF ChoiceField as a representation to client
In [6]: PersonSerializerWithDRFChoiceField().to_representation(ann)
Out[6]: OrderedDict([('name', 'Ann'), ('sex', 2)])
What returns NaturalChoiceField as a representation to client
In [7]: PersonSerializerNaturalChoiceField().to_representation(ann)
Out[7]: OrderedDict([('name', 'Ann'), ('sex', 'female')])
Lets compare .to_internal_value() behaviour Native DRF ChoiceField conversion external choice value to internal raises exception
In [8]: new_bob_serializer = PersonSerializerWithDRFChoiceField(data={'name': 'NewBob', 'sex': 'male'})
In [9]: new_bob_serializer.is_valid(raise_exception=True)
---------------------------------------------------------------------------
ValidationError Traceback (most recent call last)
<ipython-input-9-a86594992d60> in <module>
----> 1 new_bob_serializer.is_valid(raise_exception=True)
~/my_opensource/test_def_fields/venv/lib/python3.7/site-packages/rest_framework/serializers.py in is_valid(self, raise_exception)
241
242 if self._errors and raise_exception:
--> 243 raise ValidationError(self.errors)
244
245 return not bool(self._errors)
ValidationError: {'sex': [ErrorDetail(string='"male" is not a valid choice.', code='invalid_choice')]}
Create serializer to check NaturalChoice behaviour from external representation
In [10]: new_bob_serializer = PersonSerializerNaturalChoiceField(data={'name': 'NewBob', 'sex': 'male'})
In [11]: new_bob_serializer.is_valid(raise_exception=True)
Out[11]: True
Everything is OK and external representation was successfully converted to internal DB representation
In [12]: new_bob_serializer.validated_data
Out[12]: OrderedDict([('name', 'NewBob'), ('sex', '1')])
So, as you can see native ChoiceField doesn't handle choices as it does django admin forms
by default, but NaturalChoice field can handle it.
drf_fields.fields GetOrCreateSlugRelatedField
A SlugRelatedField that make possible either to create relations between objects that has already exists and which should be created.
Native DRF SlugRelatedField allow you to create new relation
between object has to be created and existed ones.
But sometime we want to created some object that has nested
field that represents one-to-one or one-to-many DB relationship
to existed objects and new ones.
To be more clear imagine that we have Person and Skills that person
can have. So it is represented by many-to-many relation.
So not to work with nested functionality it is easy to handle with
SlugRelatedField, but when we retrieve request to create user it can
looks like:
{
"name": "Bob",
"skills": ["Python", "Java", "C#"]
}And Python skill already exists in DB but Java and C# don't and
we want it to be created without overloading .create() of PersonSerializer.
So we have models.py
from django.db import models
class Skill(models.Model):
name = models.CharField(max_length=200)
class Person(models.Model):
name = models.CharField(max_length=255)
skills = models.ManyToManyField(Skill, on_delete=models.CASCADE)serializers.py have next content:
from rest_framework import serializers
from drf_fields.fields import GetOrCreateSlugRelatedField
from myapp.models import Person
class PersonSerializer(serializers.ModelSerializer):
skills = GetOrCreateSlugRelatedField(slug_field='name', get_or_craete=True)
class Meta:
model = Person
fields = ('name', 'skills')
drf_fields.fields TimestampField
Field that allow simply works with timestamps in seconds with client side. Originally you only can configure datetimes representation, but sometimes you need to set special field to retrieves and represents to client datetimes objects in timestamp format.
This field allow you to do it without any additional interaction.
So we have file serializers.py
from rest_framework import serializers
from drf_fields.fields import TimestampField
class PersonSerializer(serializers.Serializer):
name = serializers.CharField(max_length=100)
time = serializers.TimestampField()
drf_fields.fields TimestampFromDateField
The same field as TimestampField but for date representation.
drf_fields.fields RecursiveField
Field for recursive tree scaling with set depth.
Sometimes you can have tree database table structure.
The simples case, when you have self related one-to-many
relation in table. When you have this case - you may want to represent
this structure as a tree at the client side (for example: organization structure
of company).
All testing are provided using pytest library.
To run tests with verbose output run:
pytest -v