Directive on Input Type Receives Map instead of Object

[Dan6erbond]

What happened?

I wanted to implement a custom directive for input types called @validate.

My directive hook looks like this:

	config.Directives.Validate = func(ctx context.Context, obj interface{}, next graphql.Resolver) (res interface{}, err error) {
		if _, ok := obj.(map[string]any); ok {
			return next(ctx)
		}

		if err := validate.StructCtx(ctx, obj); err != nil {
			return nil, err
		}

		return next(ctx)
	}

What did you expect?

I expected the validate.StructCtx to be called, and obj to be of the type model.CreateCarInput.

Minimal graphql.schema and models to reproduce

directive @validate on OBJECT | INPUT_OBJECT

input CreateCarInput @validate {
  make: String! @goTag(key: "validate", value: "notblank")
  model: String!
  type: String!
  year: Int!
}

versions

• go run github.com/99designs/gqlgen version v0.17.49
• go version go version go1.22.3 linux/amd64

[Dan6erbond]

Upon further investigation on a very barebones schema it seems the directive runs for each field of the input. This makes no sense to me because if I wanted that behavior the validate directive would be configured to be set on INPUT_FIELD_DEFINITION.

Sample schema:

directive @validate on INPUT_OBJECT

type Todo {
  id: ID!
  text: String!
  done: Boolean!
  user: User!
}

type User {
  id: ID!
  name: String!
}

input NewTodo @validate {
  text: String!
  userId: String!
}

type Mutation {
  createTodo(input: NewTodo!): Todo!
}

Directive:

func validate(ctx context.Context, obj interface{}, next graphql.Resolver) (res interface{}, err error) {
	pctx := graphql.GetPathContext(ctx)
	fmt.Println(*pctx.Field)

	res, err = next(ctx)

	fmt.Printf("Validating object %s of type %T\n", res, res)

	return
}

Output:

text
Validating object Test of type string
userId
Validating object 1 of type string