How do I use these custom directives?

[ahokinson]

Do I need to add them to the Schema creation under directives or add them as middleware to GraphQL?

I'm really interested in writing my own directives to inject some code to remove/add to my query (as is suggested here) and your repo seems like a good framework to achieve this with Graphene (which is lacking any documentation on implementing custom directives).

Right now, I'm getting this error:

AssertionError: Schema directives must be List[GraphQLDirective] if provided but got: [<class 'core.directives.numbers.FloorDirective'>].

Do you have any advice for getting these to work? (I know this repo is 2 years old)

[timkindberg]

I have the same question... how the heck do you use these, and how do I write my own?!

[janbaykara]

According to the tests:

1. Create directive classes that inherit from the BaseCustomDirective (explanation below):
   

   graphene-custom-directives/graphene_custom_directives/directives/list.py

   Lines 9 to 15 in 56d0cd7

   	class ShuffleDirective(BaseCustomDirective):
   	@staticmethod
   	def process(value, directive, root, args, context, info):
   	if value:
   	random.shuffle(value)
   	return value

2. Add the middleware

   graphene-custom-directives/tests/test_string_directives.py

   Line 70 in 56d0cd7

   result = schema.execute(query, middleware=[CustomDirectivesMiddleware()])

3. Initialise the schema with all these directives

   graphene-custom-directives/tests/test_string_directives.py

   Line 27 in 56d0cd7

   schema = graphene.Schema(query=QueryRoot, directives=CustomDirectiveMeta.get_all_directives())

Now the middleware runs on every resolver, looping through the registered and initialised and installed directives

graphene-custom-directives/graphene_custom_directives/middleware.py

Lines 23 to 25 in 56d0cd7

	for directive in field.directives:
	directive_class = CustomDirectiveMeta.REGISTRY[directive.name.value]
	new_value = directive_class.process(new_value, directive, root, args, context, info)

The predefined directives in this package seem to register themselves due to their inheritance of the BaseCustomDirective class...

graphene-custom-directives/graphene_custom_directives/directives/list.py

Line 9 in 56d0cd7

class ShuffleDirective(BaseCustomDirective):

graphene-custom-directives/graphene_custom_directives/middleware.py

Lines 48 to 49 in 56d0cd7

	class BaseCustomDirective(six.with_metaclass(CustomDirectiveMeta, GraphQLDirective)):
	__metaclass__ = CustomDirectiveMeta

... which itself relies on CustomDirectiveMeta which auto-registers itself to the middleware:

graphene-custom-directives/graphene_custom_directives/middleware.py

Lines 30 to 41 in 56d0cd7

	class CustomDirectiveMeta(type):
	REGISTRY = {} # Maps between ndb.Model to its GraphQL type
	def __new__(mcs, name, bases, attrs):
	newclass = super(CustomDirectiveMeta, mcs).__new__(mcs, name, bases, attrs)
	if name != 'BaseCustomDirective':
	mcs.register(newclass)
	return newclass
	@classmethod
	def register(mcs, target):
	mcs.REGISTRY[target.get_name()] = target

All the registered directives are pulled into the schema via that get_all_directives:

graphene-custom-directives/graphene_custom_directives/middleware.py

Lines 43 to 45 in 56d0cd7

	@classmethod
	def get_all_directives(cls):
	return [d() for d in cls.REGISTRY.values()]

Writing directives themselves seems pretty simple: they are wrapper functions for resolvers which, as we saw from the above code examples, relies on a static process method:

graphene-custom-directives/graphene_custom_directives/directives/list.py

Lines 9 to 15 in 56d0cd7

	class ShuffleDirective(BaseCustomDirective):
	@staticmethod
	def process(value, directive, root, args, context, info):
	if value:
	random.shuffle(value)
	return value

[janbaykara]

I've also had to change the root, args, context, info pattern of arguments in CustomDirectivesMiddleware to the root, info pattern of the latest Graphene lib.