Is it possible to not return any data when using a GraphQL mutation?

Question

I have several GraphQL queries and mutations, now I’m trying to implement a delete mutation without returning any data:

    type Mutation{
        addElement(element: ElementData): ID
        removeElement(id: ID): ┬┐?
    }

However, it seems to be required to have a return value for the delete operation. Is there a way to perform an “empty” response in GraphQL? I would like to avoid things like returning a boolean or status flag if possible.

I’m not sure on what are the best practices for GraphQL delete operations.

Max 1,0561 gold badge12 silver badges20 bronze badges · Accepted Answer · 2020-03-11 06:30:41Z

79

According to this Github issue you cannot return nothing.

You can define a return type which is nullable e.g.

type Mutation {
  addElement(element: ElementData): ID
  removeElement(id: ID): Boolean
}

But I suggest you return the id of the deleted element, because if you want to work with a cached store you have to update the store when the delete mutation has ran successfully.

edited Mar 11, 2020 at 6:30

Max

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answered Jun 27, 2017 at 6:25

Locco0_0

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2

29

In case of deletion you are better off returning the product ID, as suggested (since it’s graphql, perhaps even the whole product). However, some operations truly require no data. For those cases one could define type Void and then do someOperation(input: InputObject!): Void to indicate the intent clearly.

– Avius

Oct 15, 2018 at 15:20
1

An example of a mutation that needs to return value is a logout, which would just destroy the session.

– Sandy

Apr 2, 2022 at 9:28

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score 34 · Accepted Answer · 2021-09-12 18:33:20Z

(A) Solution with `graphql-scalars`

The original answer is below.

Here is another one solution with graphql-scalars library:

install npm install graphql-scalars and then
import their Void type: https://www.graphql-scalars.dev/docs/scalars/void

(B) Solution with a custom `scalar`

Note: design with void-result from mutations goes against “GQL best practices”

This example was written for NodeJS Apollo Framework, but it is pretty easy to convert the implementation for your language/framework

I’m pretty sure: there is an NPM-package named graphql-void but if you don’t want to add another one dependency just copy this code.

1. define `Void`-scalar in your schema

# file: ./schema.gql

scalar Void

2. implement resolver

// file ./scalar-void.js

import { GraphQLScalarType } from 'graphql'

const Void = new GraphQLScalarType({
    name: 'Void',

    description: 'Represents NULL values',

    serialize() {
        return null
    },

    parseValue() {
        return null
    },

    parseLiteral() {
        return null
    }
})
export Void

3. add the resolver to ApolloServer

Add the Void resolver to the options of your instance of Apollo Server:

# file: ./server.js

import { ApolloServer } from 'apollo-server-express'
import { Void } from './scalar-void'

const server = new ApolloServer({
    typeDefs,  // use your schema
    resolvers: {
        Void: Void,
        // ... your resolvers
    },
    
})

4. use `Void` for your mutations in the schema

Finally, use the new scalar in your schema:

# file: ./schema.gql

type Mutation{
    addElement(element: ElementData): ID
    removeElement(id: ID): Void
}

What part of the linked “GQL best practices” do you suggest is saying that a void-returning mutation is bad practise? I was unable to find any such recommendation. — Sep 28, 2020 at 9:04
@MEMark graphql-rules.com/rules/mutation-payload : “Every mutation should have a unique payload type” . and I’m going to update the link in the answer — Jul 22, 2021 at 18:21

score 8 · Accepted Answer · 2020-08-17 08:05:42Z

If you use TypeScript and graphql-codegen:

In the GraphQL schema:

scalar Void

type Mutation {
  removeElement(id: ID): Void
}

In the codegen config for resolvers:
```
config:
  scalars:
    Void: "void"
```

With this config TypeScript will ensure that nothing is returned from the removeElement mutation resolver. And the returning value for the mutation will always be null on the GraphQL side.

score 1 · Accepted Answer · 2021-09-07 05:23:17Z

1

Check out graphql-scalars Void. This is standard boilerplate for all of my GraphQL projects.

npm i graphql-scalars

edited Sep 7, 2021 at 5:23

answered Aug 27, 2021 at 20:16

user1050483

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Is it possible to not return any data when using a GraphQL mutation?