Till what stage do I have to return errors in Go?

Question

I'm using Go and Gin Gonic to test and exercise some basics in Go. I first did some syntax and basis exercising already.

I've a main.go (using Gin Gonic) in which I define paths like r.GET(/todo, handler). I've a hander.go in which I describe the handlers like this:

func GetTodoListHandler(c *gin.Context) {
    c.JSON(http.StatusOK, todo.Get())
}

At last I have some todo/todo.go where I define my todo struct and functions.

Now my question, till what stage do I have to return errors?

In my todo/todo.go I have the Get() function. It uses another helper function which can have a possible error e.g.

location, err := helper(blabla)
if err != nil {
    // for a pointer we can return a nil
    return nil, err
}

Now should I return the possible error from the helper function to the Get function and from the get function back to the handler function or not? Till what stage do I have to return these errors, is it always till the handler?

Answer 1

I would do this:

func GetTodoListHandler(c *gin.Context) {
    list, err := todo.Get()
    if err != nil {
        c.String(http.StatusInternalServerError, err.Error())
    }
    c.JSON(http.StatusOK, list)
}

and have todo.Get return (list, error).

Your http handlers, like GetTodoListHandler, should never return the errors, but send responses/status codes to the client.