Ignoring

endpoints.go

// There are existing structs for Request -> Response dataflow as well as
// a struct for the Product;
//
// In this case we are mapping the Input type to a Request type see yaml and grapqql files
//
// Here's the struct we map to:

type CreateProductRequest struct {
	Name        string `json:"name"`
	GTIN        string `json:"gtin"`
	Description string `json:"description"`
}

// You can see that there is no mapping possible for 'clientMutationId'
// In fact, this type is returned back to the caller, so it should be preserved 
// during query execution — in a resolver function mapping from CreareProductRequest
// to a generated 'CreateProductPayload'

gqlgen.yaml

models:
  CreateProductInput:
    fields:
      clientMutationId:
        resolver: true
    model: <proprietary_repo>/endpoints.CreateProductRequest

schema.graphql

type Product implements Node {
  """The ID of an object"""
  id: ID!
}

type Query {
  getProductsByName(name: String!, before: String, after: String, first: Int, last: Int): ProductConnection

  """Fetches an object given its Globally Unique ID"""
  node(
    """The ID of the object"""
    id: ID!
  ): Node
}

type Mutation {
  createProduct(input: CreateProductInput): CreateProductPayload
}

input CreateProductInput {
  clientMutationId: String!
  name: String!
  gtin: String!
  description: String!
}

type CreateProductPayload {
  clientMutationId: String!
  edge: ProductEdge
}

"""An object with a Globally Unique ID"""
interface Node {
  """The ID of the object."""
  id: ID!
}

type ProductConnection {
  """Information to aid in pagination."""
  edges: [ProductEdge]

  """Information to aid in pagination."""
  pageInfo: PageInfo!
}

type ProductEdge {
  """cursor for use in pagination"""
  cursor: String!

  """The item at the end of the edge"""
  node: Product
}

"""Information about pagination in a connection."""
type PageInfo {
  """When paginating forwards, the cursor to continue."""
  endCursor: String

  """When paginating forwards, are there more items?"""
  hasNextPage: Boolean!

  """When paginating backwards, are there more items?"""
  hasPreviousPage: Boolean!

  """When paginating backwards, the cursor to continue."""
  startCursor: String
}