Unable to use UUID for ID types within gqlgen's GraphQL models

Question

I'm trying to use a UUID type (from module github.com/gofrs/uuid) within Go models. I do usually define models manually, unless I know they won't be augmented. This is what I currently have:

package model

import "github.com/gofrs/uuid"

type Category struct {
    ID          uuid.UUID `json:"id"`
    Name        string    `json:"name"`
    Description string    `json:"description"`
    Picture     string    `json:"picture,omitempty"`
}

# GraphQL Schema

...

type Category {
  id: ID!
  name: String!
  description: String!
  picture: String
}

The gqlgen configuration file looks like:

autobind:
  - <module-id>/path/to/model

...

models:
  ID:
    model:
      - github.com/99designs/gqlgen/graphql.ID
      - github.com/gofrs/uuid.UUID
  Int:
    model:
      - github.com/99designs/gqlgen/graphql.Int
      - github.com/99designs/gqlgen/graphql.Int32
      - github.com/99designs/gqlgen/graphql.Int64

...

schema:
  - graph/*.graphql

struct_tag: json

With this setup, I get this error message:

validation failed: packages.Load: /path/to/application/graph/prelude.generated.go:2177:17: ec.unmarshalInputID undefined (type *executionContext has no field or method unmarshalInputID)
/path/to/application/graph/prelude.generated.go:2182:12: ec._ID undefined (type *executionContext has no field or method _ID)

exit status 1
graph/resolver.go:3: running "go": exit status 1

Is there a way to use the UUID type "natively" for IDs without resorting in string types and doing the auto-conversion manually?

I was under the assumption that this general use case was covered by the framework

Updates

I went ahead and send a pull request for this work. I think this should be something most people will benefit from these days, where UUIDs are used (or adopted) more often.

If it's not covered ... well, the current maintainer is rather quick when it comes to supporting new PRs. ;) Otherwise, you could create a custom model `type ID uuid.UUID` with `uuid.UUID` coming from `github.com/gofrs/uuid.UUID`, implement the marshaling logic there and reference this custom type as `model` for `ID` in the config file. — NotX, Aug 04 '23 at 20:39

score 0 · Accepted Answer · answered Aug 06 '23 at 23:56

This implementation should work (with some adjustments around packages names, identifiers, etc.):

// uuid.go

package graphql

import (
    "errors"
    "io"

    "github.com/gofrs/uuid"
)

func MarshalUUID(t uuid.UUID) Marshaler {
    if t.IsNil() {
        return Null
    }
    return WriterFunc(func(w io.Writer) {
        _, _ = io.WriteString(w, t.String())
    })
}

func UnmarshalUUID(v interface{}) (uuid.UUID, error) {
    if str, ok := v.(string); ok {
        return uuid.FromString(str)
    }
    return uuid.Nil, errors.New("input must be an RFC-4122 formatted string")
}

I created a pull request with this exact implementation. If merged, this wouldn't be needed anymore because it will be a built-in behavior.

Unable to use UUID for ID types within gqlgen's GraphQL models

Updates

1 Answers1