Consumers convert the client’s input into an internal format defined as a schematics model. The mapping of incoming data to one of the available consumers is based on the client’s Content-Type header. If this is missing and no default consumer is defined, the client will receive a HTTP 406 error (Content not acceptable).

Defining consumers for a request handler is done using the consumes decorator on the class definition:

@s.consumes(s.MediaType.ApplicationJson, model=Model)
class MyHandler(s.RequestHandler):

Create custom consumer

Creating a custom consumer is as easy as subclassing the ConsumerBase class. See the JsonConsumer for example:

class JsonConsumer(ConsumerBase):

    CONTENT_TYPE = ContentType('application/json')

    def consume(self, handler, model):
        return model(**json.loads(handler.request.body))

Content Types

The CONTENT_TYPE class level variable maps a certain Content-Type header to this consumer. The consume(handler, model) method converts the request body to an instance of the model class.

In situations where you need to accept the same content type, but the model has different versions, you can use the vendor and version parameters to the content type definition. This allows for multiple consumers for the same serialization format like json but different versions of the data. See for example the following two definitions and their respective content type value:

ContentType('application/json') == 'application/json'

ContentType('application/json', version='1.1', vendor='corp') == \

If you create two consumers for both content types, the client can decide which version is sent.

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