Does Ferry support mutations that return Union types such as the example snippet below

Error generating classes for mutation that returns a union about ferry HOT 3 OPEN

humphrey commented on June 1, 2024

Error generating classes for mutation that returns a union

from ferry.

Comments (3)

humphrey commented on June 1, 2024 1

Hi!

Can you share the mutation that leads to that error?

Sure thing! Here is the mutation.

mutation UpdatePrefs($data: UpdatePrefsInput!) {
  updatePrefs(data: $data) { 
    ...MyPrefs
    ... on InputError { message }
    ... on FieldError {
      message
      fieldErrors { field, messages }
    }
  }
}

fragment MyPrefs on MyPrefs { dateFormat, firstDayOfWeek }

And here is a full cut down schema needed to reproduce. FYI, this is a simple reproducable adaption from my real schema and mutation (I've deleted most of my code and renamed a number of things for this example). I copied this to a new project with just a schema.graphql and a .graphql file for my mutation, and I get the same error.

union UpdatePrefsResponse = MyPrefs | FieldErrors | SimpleMutationError

type Mutation {
  updatePrefs(data: UpdatePrefsInput!): UpdatePrefsResponse!
}

input UpdatePrefsInput {
  dateFormat: String!
  firstDayOfWeek: Int!
}

type MyPrefs {
  dateFormat: String!
  firstDayOfWeek: Int!
}

interface InputError {
  message: String!
}

type FieldErrors implements InputError {
  message: String!
  fieldErrors: [FieldErrorsField!]!
}

type FieldErrorsField {
  field: String!
  messages: [String!]!
}

type SimpleMutationError implements InputError {
  message: String!
}