Skip to main content

load_json infrastructure for Morepath

Project description

more.body_model: ``load_json`` infrastructure for Morepath
==========================================================

The idea is to recognize on an application-level what kind of JSON content
is being posted, and convert it into a Python object. You can use this
application object with ``request.body_obj``. With ``body_model`` you can
then write views that specifically match that kind model.

To use it you have to subclass your application from
``more.body_model.BodyModelApp``:

.. code-block:: python

from more.body_model import BodyModelApp

class App(BodyModelApp):
pass

.. note:: If you want to use body_model on a mounted App, make sure that both,
the base App and the mounted App are a subclass from
``more.body_model.BodyModelApp``. Otherwise it will not work.


load_json
---------

The ``App.load_json`` directive lets you define a function that turns
incoming JSON into a Python object. This behavior is shared by all views in the
application. We detect JSON with the type field ``Item`` and interpret it as an
``Item`` instance, and pass through everything else:

.. code-block:: python

@App.load_json()
def load_json(json, request):
if json.get('type') != 'Item':
return json
return Item(json['x'])

When you write a ``json`` view you automatically get the ``Item``
instance as the ``body_obj`` attribute of the ``request``:

.. code-block:: python

@App.json(model=Collection, request_method='POST')
def collection_post(self, request):
collection.add(request.body_obj)
return "success!"

You can write views that match on the class of ``body_obj`` by specifying
``body_model``:

.. code-block:: python

@App.json(model=Collection, request_method='POST', body_model=Item)
def collection_post_item(self, request):
collection.add(request.body_obj)
return "success!"


body_model
----------

To define JSON body conversion code generally for an application we can use
``App.load_json``:

.. code-block:: python

@App.load_json()
def load_json(json, request):
if is_valid_document_json(json):
return Document(title=json['title'],
author=json['author'],
content=json['content'])
# fallback, just return plain JSON
return json

Now we get a ``Document`` instance in ``Request.body_obj``, so
we can simplify ``document_collection_post``:

.. code-block:: python

@App.json(model=DocumentCollection, request_method='POST')
def document_collection_post(self, request):
if not isinstance(request.body_obj, Document):
raise webob.exc.HTTPUnprocessableEntity()
result = self.add(request.body_obj)
return request.view(result)

To only match if ``body_obj`` is an instance of ``Document`` we can
use ``body_model`` on the view instead:

.. code-block:: python

@App.json(model=DocumentCollection, request_method='POST', body_model=Document)
def document_collection_post(self, request):
result = self.add(request.body_obj)
return request.view(result)

Now you get the ``422`` error for free if no matching ``body_model``
can be found. You can also create additional ``POST`` views for
``DocumentCollection`` that handle other types of JSON content this
way.


CHANGES
=======

0.1 (2017-03-17)
----------------

* initial public release.

Project details


Release history Release notifications

This version

0.1

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for more.body-model, version 0.1
Filename, size File type Python version Upload date Hashes
Filename, size more.body_model-0.1-py2.py3-none-any.whl (8.7 kB) File type Wheel Python version py2.py3 Upload date Hashes View hashes
Filename, size more.body_model-0.1.tar.gz (6.4 kB) File type Source Python version None Upload date Hashes View hashes

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page