Non-Blocking ReadAll function for Humble

gistfile1.go

// ReadAll expects a pointer to a slice of poitners to some concrete type
// which implements Model (e.g., *[]*Todo). GetAll will send a GET request to
// a RESTful server and scan the results into models. It expects a json array
// of json objects from the server, where each object represents a single Model
// of some concrete type. It will use the RootURL() method of the models to
// figure out which url to send the GET request to.
func ReadAll(models interface{}) <-chan error {
	// We expect some pointer to a slice of models. Like *[]Todo
	// First Elem() givew us []Todo
	// Second Elem() gives us Todo
	modelsType := reflect.TypeOf(models).Elem()
	// TODO: type checking!
	modelTypePtr := modelsType.Elem()
	modelType := modelTypePtr.Elem()
	// reflect.New returns *Todo
	newModelVal := reflect.New(modelType)
	newModelInterface := newModelVal.Interface()
	newModel := newModelInterface.(Model)
	// TODO: check for a failed type assertion!
	urlRoot := newModel.RootURL()

	// Send the http request inside a goroutine
	errChan := make(chan error)
	go func() {
		res, err := http.Get(urlRoot)
		if err != nil {
			errChan <- fmt.Errorf("Something went wrong with GET request to %s. %s", urlRoot, err.Error())
			return
		}
		body, err := ioutil.ReadAll(res.Body)
		if err != nil {
			errChan <- fmt.Errorf("Error reading response body from GET request to %s: %s", urlRoot, err.Error())
			return
		}
		if err := json.Unmarshal(body, models); err != nil {
			errChan <- fmt.Errorf("Failed to unmarshal response into object, with Error: %s.\nResponse was: %s", err)
			return
		}
		errChan <- nil
	}()
	return errChan
}