Make it easier to define custom filters without django-filter

[alexkirsz]

refine_queryset lets DjangoObjectType define exactly how the queryset should be refined before being returned to the user. For instance, some objects could be filtered out according to a predicate, or some fields could be prefetched depending on what the initial query requested.

get_connection_parameters lets DjangoObjectType define the name and value of parameters that can be passed to any DjangoConnectionField that uses them.

Both these additions come as building blocks to allow custom refinements and filters without having to go through django-filter. Moreover, such filters can also be further optimized than previously allowed, as the GraphQL ResolveInfo instance is available in refine_queryset.

Example usage:

class RecipeOrderBy(graphene.Enum):
    name__ASC = 'name'
    name__DESC = '-name'

class RecipeNode(DjangoObjectType):
    class Meta:
        model = Recipe
        interfaces = (graphene.relay.Node,)

    @classmethod
    def get_connection_parameters(cls):
        return {
            'order_by': RecipeOrderBy()
        }

    @classmethod
    def refine_queryset(cls, qs, info, **kwargs):
        if 'order_by' in kwargs:
            qs = qs.order_by(RecipeOrderBy.get(kwargs['order_by']).value)
        # Since we have access to the GraphQL query's ResolveInfo instance through the info
        # argument, you can enable some prefetch optimizations here as well.
        return qs

[coveralls]

Coverage increased (+0.07%) to 94.59% when pulling 6fda2f6 on acu:custom-filter into f76f38e on graphql-python:master.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.