Add an array of Objects to a mutation in apollo-react

问题

I am using react-apollo on the front-end and graphcool on the backend. I have a mutation that creates a tutorial like so:

const CREATE_TUTORIAL_MUTATION = gql`
  mutation CreateTutorialMutation(
    $author: String
    $link: String
    $title: String!
    $postedById: ID!
    $completed: Boolean!
  ) {
    createTutorial(
      author: $author
      link: $link
      title: $title
      postedById: $postedById
      completed: $completed
    ) {
      author
      link
      title
      postedBy {
        id
        name
      }
      completed
    }
  }
`

It gets called in a submit handler like so...

this.props.createTutorialMutation({
      variables: {
        author,
        link,
        title,
        completed: false,
        postedById
      }
    })

Everything works wonderfully.

Now I want to add a set of tags to when I create a new tutorial. I created the input field and connected it so that the tags variable is an array of objects, each with a tag id and the tag text.

If I try and add the tags field to the mutation it needs a scalar type. But there is doesn't seem to be a scalar type for an array of objects.

If I pass the tag variable in as a parameter when I call the mutation how do I fill in the Scalar type field in the mutation ( on line 148 here https://github.com/joshpitzalis/path/blob/graphQL/src/components/Add.js) and in the schema?

I am new to graphQL and I understand that I might be approaching this completely the wrong way. If that is the case, how do I add an array of objects to a mutation in graphQL?

回答1:

You should add a new Tag type to your schema file and connect it to Tutorial with a new relation:

type Tutorial {
  author: String
  completed: Boolean
  link: String
  title: String!
  id: ID! @isUnique
  createdAt: DateTime!
  updatedAt: DateTime!
  postedBy: User @relation(name: "UsersTutorials")
  tags: [Tag!]! @relation(name: "TutorialTags")
}

type Tag {
  id: ID!
  tag: String!
  number: Int!
  tutorials: [Tutorial!]! @relation(name: "TutorialTags")
}

Then you can create a new tutorial and new tags using a nested create mutation like this:

const CREATE_TUTORIAL_MUTATION = gql`
  mutation CreateTutorialMutation(
    $author: String
    $link: String
    $title: String!
    $tags: [TutorialtagsTag!]!
    $completed: Boolean!
    $postedById: ID!
  ) {
    createTutorial(
      author: $author
      link: $link
      title: $title
      tags: $tags
      completed: $completed
      postedById: $postedById
    ) {
      author
      link
      title
      postedBy {
        id
        name
      }
      completed
      tags {
        id
        text
      }
    }
  }
`

This post gives more background about other approaches and their trade-offs: https://www.graph.cool/forum/t/how-do-i-add-an-array-of-objects-to-a-mutation-in-apollo-react/365/6?u=nilan

回答2:

What i understand by your requirement is that if you have the following code

const user = {
    name:"Rohit", 
    age:27, 
    marks: [10,15], 
    subjects:[
        {name:"maths"},
        {name:"science"}
    ]
};

const query = `mutation {
        createUser(user:${user}) {
            name
        }
}`

you must be getting something like

"mutation {
        createUser(user:[object Object]) {
            name
        }
}"

instead of the expected

"mutation {
        createUser(user:{
            name: "Rohit" ,
            age: 27 ,
            marks: [10 ,15 ] ,
            subjects: [
                {name: "maths" } ,
                {name: "science" } 
                ] 
            }) {
            name
        }
}"

If this is what you wanted to achieve, then gqlast is a nice tag function which you can use to get the expected result

Simply grab the js file from here and use it as:

const user = {
    name:"Rohit", 
    age:27, 
    marks: [10,15], 
    subjects:[
        {name:"maths"},
        {name:"science"}
    ]
};

const query = gqlast`mutation {
        createUser(user:${user}) {
            name
        }
}`

The result stored in the variable query will be :

"mutation {
        createUser(user:{
            name: "Rohit" ,
            age: 27 ,
            marks: [10 ,15 ] ,
            subjects: [
                {name: "maths" } ,
                {name: "science" } 
                ] 
            }) {
            name
        }
}"

来源：https://stackoverflow.com/questions/45253671/add-an-array-of-objects-to-a-mutation-in-apollo-react