[Draft] Multi return

[EwenQuim]

⚠️ Implementation in draft, don't hesitate to ask for spec changes.

Spec

Currently, return type is either JSON or XML for the whole app. This needs to be improved.

The route /recipes should send HTML with a list of recipes if the Accept Header is "text/html", or JSON if the Accept Header is "application/json", or XML if the Accept Header is "application/xml". This allows to build a traditional website in the same time as building an API.

This change is of course backward-compatible and existing controller will not change current behaviour. Performance should also not be degraded.

Example

A controller might look like this (see multi_return_test.go for more examples).

fuego.Get(s, "/data", func(c ContextNoBody) (DataOrTemplate[MyType], error) {
	entity := MyType{Name: "Ewen"}

	return DataOrTemplate[MyType]{
		Data: entity, // Used when asking for JSON or XML
		Template: MyTemplate(entity) // std template, Templ or Gomponent rendered when asking for HTML
	}, nil
})