A field in GraphQL must always have a type. GraphQL has the concept of null but null is not itself a type -- it simply represents the lack of value.

There is no void type in GraphQL. However, types are nullable by default, so regardless of a field's type, your resolver can return nothing and the field will simply resolve to null. So you can just do

type Mutation {

  deleteQueue(input: QueueInput!): Boolean #or any other type

}

Or if you want a scalar that specifically represents null, you can create your own.

const { GraphQLScalarType } = require('graphql')



const Void = new GraphQLScalarType({

  description: 'Void custom scalar',

  name: 'Void',

  parseLiteral: (ast) => null,

  parseValue: (value) => null,

  serialize: (value) => null,

})

and then do

type Mutation {

  deleteQueue(input: QueueInput!): Void

}

That said, it's common practice to return something. For deletions, it's common to return either the deleted item or at least its ID. This helps with cache-management on the client side. It's also becoming more common to return some kind of mutation payload type to better encapsulate client errors.

There's any number of fields you could include on a payload type like this:

type Mutation {

  deleteQueue(input: QueueInput!): DeleteQueuePayload

}



type DeleteQueuePayload {

  # the id of the deleted queue

  queueId: ID



  # the queue itself

  queue: Queue



  # a status string

  status: String



  # or a status code

  status: Int



  # or even an enum

  status: Status



  # or just include the client error

  # with an appropriate code, internationalized message, etc.

  error: ClientError



  # or an array of errors, if you want to support validation, for example

  errors: [ClientError!]!

}

DeleteQueuePayload could even be a union of different types, enabling the client to use the __typename to determine the result of the mutation.

What information you expose, however, depend on your specific needs, and what specific pattern you employ is boils down to opinion.

See here and here for additional discussion and examples.