Faced an error that resolve doesn’t work in GraphQL-Ruby.

Recently started learning GraphQL because I’ll use it in a company. Roughly, I understood but I spent 3 hours solving a problem. The environment is that the backend is Ruby on Rails and the frontend is Next js.

The problem

It was that ‘resolve’ in mutation doesn’t work. Even if I sent a request to the server, the log became like this.

Started POST "/graphql" for ::1 at 2024-04-28 20:51:34 -0700
Processing by GraphqlController#execute as */*
  Parameters: {"operationName"=>"createTodo", "variables"=>{"title"=>"fdsds", "completed"=>true}, "query"=>"mutation createTodo($title: String!, $completed: Boolean!) {\n  createTodo(title: $title, completed: $completed) {\n    todo {\n      id\n      title\n      completed\n      __typename\n    }\n    errors\n    __typename\n  }\n}", "graphql"=>{"operationName"=>"createTodo", "variables"=>{"title"=>"fdsds", "completed"=>true}, "query"=>"mutation createTodo($title: String!, $completed: Boolean!) {\n  createTodo(title: $title, completed: $completed) {\n    todo {\n      id\n      title\n      completed\n      __typename\n    }\n    errors\n    __typename\n  }\n}"}}
Completed 200 OK in 7ms (Views: 1.2ms | ActiveRecord: 0.0ms | Allocations: 1281)

I thought that the error was related to Ruby on Rails, but it showed up on the console of the client, which meant that the cause was the frontend.

The error I got

new.tsx:28 ApolloError: Field 'createTodo' is missing required arguments: input
Field 'createTodo' doesn't accept argument 'title'
Field 'createTodo' doesn't accept argument 'completed'
Variable $title is declared by createTodo but not used
Variable $completed is declared by createTodo but not used

The corresponding code was below.

const CREATE_TODO = gql`
  mutation createTodo($title: String!, $completed: Boolean!) {
    createTodo(title: $title, completed: $completed) {
      todo {
        id
        title
        completed
      }
    }
  }
`;

The solution

The code has to be like this.

const CREATE_TODO = gql`
  mutation createTodo($title: String!, $completed: Boolean!) {
    createTodo(input: { title: $title, completed: $completed }) {
      todo {
        id
        title
        completed
      }
    }
  }
`;

‘input’ has to be used in the code.

The result of the request is like this.

 TRANSACTION (0.1ms)  begin transaction
  ↳ app/graphql/mutations/create_todo.rb:13:in `resolve'
  Todo Create (2.3ms)  INSERT INTO "todos" ("title", "completed", "created_at", "updated_at") VALUES (?, ?, ?, ?)  [["title", "vdsvdfvdf"], ["completed", 1], ["created_at", "2024-04-29 03:52:33.844106"], ["updated_at", "2024-04-29 03:52:33.844106"]]
  ↳ app/graphql/mutations/create_todo.rb:13:in `resolve'
  TRANSACTION (0.5ms)  commit transaction
  ↳ app/graphql/mutations/create_todo.rb:13:in `resolve'
Completed 200 OK in 70ms (Views: 0.2ms | ActiveRecord: 2.9ms | Allocations: 3674)

Could save the object!

Feel free to reach out to me on LinkedIn, which you can find below. Looking forward to connecting!

https://www.linkedin.com/in/tomoharu-tsutsumi-56051a126/