How to set null to field in graphql?

Question

We use graphql on our project and use graphql-java 2.3.0 (we plan to update but it is not possible at the moment).

I'm trying to perform such mutation:

  mutation {
    UPDATE_User(

      id:3,
      type: null
    ) {id}
  }

Response:

{
  "errors": [
    {
      "validationErrorType": "WrongType",
      "message": "Validation error of type WrongType: argument value EnumValue{name='null'} has wrong type",
      "locations": [
        {
          "line": 5,
          "column": 7
        }
      ],
      "errorType": "ValidationError"
    }
  ],
  "data": null
}

Answer 1

Null keyword is a relatively new addition to the GraphQL spec, and the graphql-java version you're using doesn't yet have it implemented. In fact, even 3.0.0 still doesn't have it. The soon-to-be-released 4.0 will have support for the null keyword.
And the reason it is treated as an enum is because unquoted strings are normally enums, null being the only exception. This is also explained in this issue.