graphqlclientgen

graphqlclientgen

Here Be Dragons 🐉

This is an experiment of generating GraphQL clients in Golang. It's heavily inspired by gqlgen.

• Goals
  • Structure config and generated clients in a future proof way to enable redesign of codegen
  • Single client generated for entire schema
  • ProtoClient interface to support multiple protocols and custom clients
  • Use static types in client interface to check api compability during build time
  • Enable field selection in client to partially fetch objects
• Limitations
  • No support for arguments on fields (yet)

Get started

1. Add graphqlclientgen

   go get -tool github.com/loa/graphqlclientgen"
   

2. Create a new directory and run graphqlclientgen init

   mkdir exampleclient
   cd exampleclient
   
   go tool graphqlclientgen init --schema-path='../graph/*.graphqls'
   

3. Run generate (init creates exampleclient.go with go gen comment)

   go generate -v ./...
   

Examples

func Example() {
  // create client, supports custom protocols through ProtoClient interface
  c := client.New(graphqlclient.NewHttpClient("http://localhost:8080/query"))

  todo, err := c.CreateTodo(context.TODO(),
    // static typed inputs
    client.NewTodo{
      Text:   "bar",
      UserId: "5",
    },
    // explicit requested fields, easy to use with auto-complete
    client.TodoFields{
      client.TodoFieldID,
      client.TodoFieldText,
      // supports requesting specific fields of related objects
      client.TodoFieldUser{
        client.UserFieldID,
        client.UserFieldName,
      },
    })

  if err != nil {
    var gerr graphqlclient.Error
    if errors.As(err, &gerr) {
      // match errors by extension
      if gerr.ExtensionEqualString("code", "NOT_FOUND") {
        // handle user not found
      } else if gerr.ExtensionEqualString("code", "INVALID_INPUT") {
        // handle invalid text input
      }
    }
  }
}