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.
args is the hash of arguments passed to the field.
context is the context object passed throughout the query.
info is the resolver info.

Example¶

This middleware only continues evaluation if the field_name is not 'user'

class AuthorizationMiddleware(object):
    def resolve(self, next, root, args, context, info):
        if info.field_name == 'user':
            return None
        return next(root, args, context, info)

And then execute it with:

result = schema.execute('THE QUERY', middleware=[AuthorizationMiddleware()])

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