graphene/docs/execution/middleware.rst

43 lines
1.1 KiB
ReStructuredText
Raw Normal View History

2016-10-31 07:32:00 +03:00
Middleware
==========
You can use ``middleware`` to affect the evaluation of fields in your schema.
A middleware is any object that responds to ``resolve(*args, next_middleware)``.
Inside that method, it should either:
- Send ``resolve`` to the next middleware to continue the evaluation; or
- Return a value to end the evaluation early.
Resolve arguments
-----------------
Middlewares ``resolve`` is invoked with several arguments:
- ``next`` represents the execution chain. Call ``next`` to continue evalution.
- ``root`` is the root value object passed throughout the query.
- ``info`` is the resolver info.
- ``args`` is the dict of arguments passed to the field.
2016-10-31 07:32:00 +03:00
Example
-------
This middleware only continues evaluation if the ``field_name`` is not ``'user'``
.. code:: python
class AuthorizationMiddleware(object):
2017-07-27 13:00:21 +03:00
def resolve(self, next, root, info, **args):
if info.field_name == 'user':
return None
2017-07-27 13:00:21 +03:00
return next(root, info, **args)
2016-10-31 07:32:00 +03:00
And then execute it with:
.. code:: python
result = schema.execute('THE QUERY', middleware=[AuthorizationMiddleware()])