""" http://www.django-rest-framework.org/api-guide/serializers/#serializers

Serializers allow complex data (e.g. querysets and model instances)

to be converted to native Python datatypes that can be easily rendered

into JSON, XML, or other types. Serializers also provide deserialization,

allowing parsed data to be converted back into complex types, after first

validating the incoming data.

"""

from datetime import datetime

from rest_framework import serializers # For serialization

from rest_framework.renderers import JSONRenderer # For serialization

from StringIO import StringIO # for deserilization

from rest_framework.parsers import JSONParser # For deserialization

# A simple object

class Comment(object):

def __init__(self, email, content, created=None):

self.email = email

self.content = content

self.created = created or datetime.now()

# A simple serializer

class CommentSerializer(serializers.Serializer):

email = serializers.EmailField()

content = serializers.CharField(max_length=200)

created = serializers.DateTimeField()

# Serializer that returns complete object instances with .create() and update()

class InstanceCommentSerializer(serializers.Serializer):

email = serializers.EmailField()

content = serializers.CharField(max_length=200)

created = serializers.DateTimeField()

def create(self, validated_data):

return Comment(**validated_data)

def update(self, instance, validated_data):

instance.email = validated_data.get('email', instance.email)

instance.content = validated_data.get('content', instance.content)

instance.created = validated_data.get('created', instance.created)

instance.save() # if 'Comment' was a Django Model, need to save obj

return instance

if __name__ == '__main__':

# Create a simple object

comment = Comment(email='wliu@test.com', content='foo bar')

# Create a serializer to serialize and deserialize data corresponding

# to the Comment objects

### SERIALIZE

serializer = CommentSerializer(comment) # Serialize a comment

print serializer.data # Take model, translate into Python native datatypes

# {'email': u'wliu@test.com', 'content': u'foo bar',

# 'created': datetime.datetime(2014, 10, 9, 16, 20, 9, 822774)}

# Finalize the serialization process by rendering the data into JSON

json = JSONRenderer().render(serializer.data)

print "JSON is " + json

# # '{"email": "wliu@test.com", "content": "foo bar",

#"created": "2014-10-9T16:20:09.822"}'

### DESERIALIZE

stream = StringIO(json)

data = JSONParser().parse(stream) # Parse stream to Python native datatype

serializer = CommentSerializer(data=data) # Restore native datatypes into a dic of validated data

serializer.is_valid() # True # Call is_valid() before accessing data

serializer.validated_data

# # {'content': 'foo bar', 'email': 'wliu@test.com',

#'created': datetime.datetime(2014, 10, 9, 16, 20, 09, 822243)}

### INSTANCES

# If we want to return complete object instances based on validated data

# we need to implement .create() and update() methods