Develop Reference

How to serialize JSON Request data from serializer in Django?

I am trying to serialize a json data through serializers.Serializer
{
"data": {
"phoneNumber": "1234567890",
"countryCode": "+11",
"otp": "73146",
}
}
The sterilizer class I wrote for it
class VerifyOtpSerializer(serializers.Serializer):
phone_number = serializers.CharField(max_length=225, source='phoneNumber', required=True)
country_code = serializers.CharField(max_length=225, source='countryCode', required=True)
otp = serializers.CharField(max_length=255, required=True)
and also
I don't know why source is not working, I tried the JSON in the picture below but still it's saying the field is required

source value is what the passed value's key will be changed into. So source value is expected to be on your Model.
The name of the attribute that will be used to populate the field.
What you really want is something that changes camel case payload into a snake case. Just use djangorestframework-camel-case and remove source from your serializer fields.

Your keys are wrong in the request. as Tom said the source should be an attribute of the model object. so you have to match keys in request and serializer
change phoneNumber > phone_number
change countryCode > country_code

The response object you are are sending to your serializer is in correct. The key of your request object should be exactly what you have defined in your serializer.
Try sending this to your serializer.
{
"data" : {
"phone_number":"1234567890",
"country_code":"+11",
"otp":"73146"
}
}

Return custom JSON response from ListAPIView Django 3.0 Rest Framework

I have created an API using DRF That is able to list and view particular records based on the URL pattern specified. For example:
for the request:
curl -v http://127.0.0.1:8000/get_details/120001/
I am able to get a response:
[
{
"subject": "Data Structures",
"course": "CSE"
},
{
"subject": "Thermodynamics",
"course": "Chemistry"
},
{
"subject": "Organic Chemistry",
"course": "Chemistry"
},
{
"subject": "Optics",
"course": "Physics"
}
]
Where '120001' is the user_id the database is searched against.
But the I want the response in the following format:
{'Chemistry': ['Thermodynamics', 'Organic Chemistry'], 'CSE': ['Data Structures'], 'Physics': ['Optics']}
(content wise, I am not considering indentation and other factors)
While I am able to write code for the logic of how to create and populate this dictionary, I am unable to figure out how to return this as response and from where.
I am using generics.ListAPIView as the view class.
Here is my model (models.py):
class Subject(models.Model):
user_id = models.CharField(null = False, max_length=10)
subject = models.CharField(max_length=50)
course = models.CharField(max_length=50)
def __str__(self):
return self.subject
Serializer (serializers.py):
class SubjectSerializer(serializers.ModelSerializer):
class Meta:
model = Subject
fields = ['subject', 'course']
and, views.py (for the first output in default format):
class SubjectView(generics.ListAPIView):
serializer_class = SubjectSerializer
def get_queryset(self):
username = self.kwargs['user_id']
return Subject.objects.filter(user_id = username).only('subject','course')
I have written a logic to create the dictionary to send as response (as described in my desired output) by extracting values using Subject.objects.values(....) and then looping through the results to create my dictionary but I just don't get where (that is, which function) to write it in and return from.
Is there any function provided by the generics.ListAPIView class that can allow me to do this? And if not, then what other alternative approach can I try?
I am an absolute beginner at Django and any help will be appreciated. Also, it will be of great help if anyone can suggest me a practical guide/tutorial/playlist from where I can learn DRF through code examples to speed up my learning process.
Thank you!

You need to override to_representation method of Serializer
from docs
There are some cases where you need to provide extra context to the
serializer in addition to the object being serialized.
class SubjectSerializer(serializers.ModelSerializer):
class Meta:
model = Subject
fields = ['subject', 'course']
def to_representation(self, instance):
data = super(SubjectSerializer, self).to_representation(instance)
# manipulate data here
return data

Jsonify flask-sqlalchemy many-to-one relationship in flask

I was trying to make rest apis with flask-restful where i am using flask-sqlalchemy as the ORM.Here is my model classes.
class Post(db.Model):
__tablename__ = 'post'
postid = db.Column(db.Integer,primary_key=True)
post = db.Column(db.String(64))
userid = db.Column(db.Integer,db.ForeignKey('user.userid'))
#serialize property used for serializing this class to JSON
#property
def serialize(self):
return {
'postid': self.postid,
'post': self.post,
'author':self.author
}
and
class User(db.Model):
userid = db.Column(db.Integer,primary_key=True)
username = db.Column(db.String(30))
email = db.Column(db.String(20))
posts = db.relationship('Post',backref="author",lazy='dynamic')
#serialize property used for serializing this class to JSON
#property
def serialize(self):
return {
'username': self.username,
'email': self.email
}
And the database is populated.now i am trying to make the json out of this
class PostList(Resource):
def get(self):
posts = DL_models.Post.query.all()
posts = [post.serialize for post in posts]
return { 'posts': posts }
api.add_resource(PostList, '/twitter/api/v1.0/posts', endpoint = 'posts')
This works perfect when i change serialize method in Post to
#property
def serialize(self):
return {
'postid': self.postid,
'post': self.post,
'author':self.postid
}
This returns expected json output but when i am changing to 'author':self.author i am getting a error
TypeError: <app.DL_models.User object at 0x7f263f3adc10> is not JSON serializable
I understand that i have to call serialize on those nested objects as well but i could not figure out how to do it.
Or please share your experience to encode relationships in sqlalchemy.

Since you're already using Flask-Restful, have you considered using their built in data marshaling solution?
However, for marshaling complex data structures, I find that Marshmallow does the task about a thousand times better, even making nesting serializers within others easy. There's also a Flask extension designed to inspect endpoints and output URLs.

This is a punt but have you tried the below?
'author': self.author.username
From the error message I'm guessing it's getting to User but doesn't know what you want from it.

django serializers to json - custom json output format

I am quite new to django and recently I have a requirement of a JSON output, for which I use the following django code:
data = serializers.serialize("json", Mymodel.objects.all())
It works great, except that I get a output of:
[{"pk": 8970859016715811, "model": "myapp.mymodel", "fields": {"reviews": "3.5", "title": .....}}]
However, I would like the output to be simply either:
[{"reviews": "3.5", "title": .....}]
or,
[{"id": "8970859016715811", "reviews": "3.5", "title": .....}]
I was wondering if someone could point me to the right direction as to how to achieve this.

You can add 'fields' parameter to the serialize-function, like this:
data = serializers.serialize('xml', SomeModel.objects.all(), fields=('name','size'))
See: https://docs.djangoproject.com/en/dev/topics/serialization/
EDIT 1:
You can customize the serializer to get only the fields you specify.
From Override Django Object Serializer to get rid of specified model:
from django.core.serializers.python import Serializer
class MySerialiser(Serializer):
def end_object( self, obj ):
self._current['id'] = obj._get_pk_val()
self.objects.append( self._current )
# views.py
serializer = MySerialiser()
data = serializer.serialize(some_qs)

You'll need to write a custom Json serializer. Something like this should do the trick:
class FlatJsonSerializer(Serializer):
def get_dump_object(self, obj):
data = self._current
if not self.selected_fields or 'id' in self.selected_fields:
data['id'] = obj.id
return data
def end_object(self, obj):
if not self.first:
self.stream.write(', ')
json.dump(self.get_dump_object(obj), self.stream,
cls=DjangoJSONEncoder)
self._current = None
def start_serialization(self):
self.stream.write("[")
def end_serialization(self):
self.stream.write("]")
def getvalue(self):
return super(Serializer, self).getvalue()
The you can use it like this:
s = FlatJsonSerializer()
s.serialize(MyModel.objects.all())
Or you could register the serializer with django.core.serializers.register_serializer and then use the familiar serializers.serialize shortcut.
Take a look at the django implementation as a reference if you need further customization: https://github.com/django/django/blob/master/django/core/serializers/json.py#L21-62

I just came across this as I was having the same problem. I also solved this with a custom serializer, tried the "EDIT 1" method but it didn't work too well as it stripped away all the goodies that the django JSON encoder already did (decimal, date serialization), which you can rewrite it yourself but why bother. I think a much less intrusive way is to inherit the JSON serializer directly like this.
from django.core.serializers.json import Serializer
from django.utils.encoding import smart_text
class MyModelSerializer(Serializer):
def get_dump_object(self, obj):
self._current['id'] = smart_text(obj._get_pk_val(), strings_only=True)
return self._current
Sso the main culprit that writes the fields and model thing is at the parent level python serializer and this way, you also automatically get the fields filtering that's already built into django's JSON serializer. Call it like this
serializer = MyModelSerializer()
data = serializer.serialize(<queryset>, <optional>fields=('field1', 'field2'))

import json
_all_data = Reporter.objects. all()
json_data = json.dumps([{'name': reporter.full_name} for reporter in _all_data])
return HttpResponse(json_data, content_type='application/json')
Here Reporter is your Model

How to add data to tastypie resources in regular django views

I am running into a problem trying to include tastypie resources in a larger json response in a regular django view. I would like to have the view return something like this (based on a queryset generated in the view, not from typical tastypie get params):
{
"success": bool,
"message": string,
"error": string,
"objects": [
{
"field_one": bar,
"field_two": foo
}
... more objects ...
]
}
where objects list is a list of serialized tastypie resources, and success, message and error are coming from somewhere else in the view.
Right now, I can't figure out how to avoid turing the serialized resource into strings before the larger dict gets build, so I have something like this currently:
{
"success": bool,
"message": string,
"error": string,
"objects": [
"{"field_one": bar, "field_two": foo..."}",
"{"field_one": baz, "field_two": foobar..."}",
...
]
}
The whole point of this is to keep the model json representations consistent, to minimize friction between using the tastypie api directly, and using the data returned in these views. I'm thinking the solution is to somehow use the full_dehydrate method on each resource without serializing them, and then adding them to the bigger dict, and then serializing that dict, but I'm not sure what serializer to use. Or, maybe there is a better way.

As is often the case, writing this up helped me find a temporary solution. Maybe someone will have some input on how to make this better.
I am using this to prepare a queryset for serialization:
def serialize_queryset(resource_class, queryset):
# hand me a queryset, i give you dehydrated resources
resource = resource_class()
dd = {}
# make meta
dd['meta'] = {}
dd['meta']['limit'] = 1000
dd['meta']['next'] = None
dd['meta']['offset'] = 0
dd['meta']['previous'] = None
dd['meta']['total_count'] = len(queryset)
# objects
dd['objects'] = []
for obj in queryset:
bundle = resource.build_bundle(obj=obj)
dehydrated_obj = resource.full_dehydrate(bundle)
dd['objects'].append(dehydrated_obj)
# return dict
return dd
And I use the Serializer from tastypie.serializer. and in using it in a sample view is goes something like:
from tastypie.serializer import Serializer
serializer = Serializer()
def my_view(request):
#... do some other view stuff ...
# prepare a queryset for serialization
queryset = MyModel.objects.filter(is_cool=True)
data = serialize_queryset(MyModel, queryset)
# add in custom stuff, determined earlier in the view somewhere
data['success'] = success
data['message'] = message
data['error'] = error
# serialize and return response
data = serializer.serialize(data)
return HttpResponse(data, mimetype='application/json')
This seems to work. Maybe you see something bad about this method, or a way to improve it?