Is it possible to not return any data when using a GraphQL mutation?
GraphqlGraphql Problem Overview
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.
Graphql Solutions
Solution 1 - Graphql
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.
Solution 2 - Graphql
graphql-scalars
(A) Solution with 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
scalar
(B) Solution with a custom > 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.
Void
-scalar in your schema
1. define # 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
},
})
Void
for your mutations in the schema
4. use Finally, use the new scalar
in your schema:
# file: ./schema.gql
type Mutation{
addElement(element: ElementData): ID
removeElement(id: ID): Void
}
Solution 3 - Graphql
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.
Solution 4 - Graphql
Check out graphql-scalars Void. This is standard boilerplate for all of my GraphQL projects.
npm i graphql-scalars