GraphQL Input Issue Repository

This is a simple GraphQL API built with Apollo Server 4 to demonstrate type validation behavior. The server defines a UserInput type and a mutation to update a user, expecting a single object. This repo is designed to replicate and test how Apollo Server handles invalid input, such as an array passed to a non-array argument.

Running the Server

Install dependencies running the following command:

npm install

Start the Server Run the following command in your terminal:

node index.js

You should see a message like:

🚀 Server ready at http://localhost:4000/

Access the Apollo Sandbox Open your browser and navigate to http://localhost:4000/. This loads the Apollo Sandbox, a web-based GraphQL IDE for testing queries and mutations.

Testing the Mutation

The server exposes a updateUser mutation that expects a single UserInput object. To test how it handles an invalid input (an array instead of an object), use the following steps:

Open Apollo Sandbox Go to http://localhost:4000/ in your browser.

Run the Mutation In the Apollo Sandbox, enter the following mutation:

mutation UpdateUser($user: UserInput!) {
    updateUser(user: $user) {
        firstName
        lastName
        businessPhone
        email
        jobTitle
    }
}

Provide the Variables In the "Variables" section of Apollo Sandbox (usually at the bottom), paste this JSON payload:

{
    "user": [
        {
            "firstName": "test",
            "lastName": "test",
            "businessPhone": "test",
            "email": "test@email.com",
            "jobTitle": "test"
        },
        {
            "firstName": "test",
            "lastName": "test",
            "businessPhone": "test",
            "email": "test@email.com",
            "jobTitle": "test"
        },
        {
            "firstName": "test",
            "lastName": "test",
            "businessPhone": "test",
            "email": "test@email.com",
            "jobTitle": "test"
        }
    ]
}

Execute the Mutation Click the "Run" or "Play" button in Apollo Sandbox.

Expected Behavior

The mutation expects a single UserInput object, but the provided payload is an array of objects. Apollo Server’s type validation rejects the request before executing the resolver, returning a single error message indicating a type mismatch.

Current Behavior

Apollo Server returns an error per element of the array:

"GraphQLError: Field \"2\" is not defined by type \"UserInput\".",