Rails Newbie: Recommendations for error handling in controller

Question

Sorry if the question is obvious, I am only starting to work with Rails.
I have a following code in several controller methods now:

respond_to do |format| if @project.save format.html { redirect_to(edit_project_url(@project), :notice => '#{user.name} added to #{role}.') } format.js else format.html { render :action => "edit" } format.js #... end end

So the question is, what is the best way to do the same thing for errors in all methods?
Is it recommended that I use save! and handle it in rescue_action?

Or should I do my own respond method and pass save in a block?

tadman · Accepted Answer · 2010-10-27 15:22:10Z

It's often more convenient to use the exception-raising variant of save and rescue that later in the block than to branch like that. The advantage to exceptions is they'll bust out of transactions.

def create @project.save! respond_to do |format| format.html { redirect_to(edit_project_url(@project), :notice => '#{user.name} added to #{role}.') } format.js end rescue ActiveRecord::RecordInvalid respond_to do |format| format.html { render :action => "edit" } format.js #... end end

You'll find that it gets really tricky to wrangle your way out of a pile of nested if statements when trying to save more than one object at a time, but a simple rescue for exceptions will handle it neatly.

def create Project.transaction do @project.save! @something_else.save! @other_stuff.save! end # ... rescue ActiveRecord::RecordInvalid # ... end

If any one of those saves blows up you'll get an exception. To ensure that all of them are displaying validation errors you might have to call .valid? on each to prime them or you will have those after the failure left untested.

This seems a good idea, but why scaffold does not go this way? Also I assume you recommend to use rescue_action if there are several such methods?
Ok, I am going to assume you meant a rescue_from or rescue_action_in_public handler for multiple methods, in which case Chubas reply here is a subset of this one and I should accept this one as an answer.
As a general rule I use rescue_from for things that cannot be easily recovered from, and rescue when I can handle it. When a create fails, typically you just render the new form again. Something more abstract generally returns a pretty "Uh oh" page.

Chubas · Accepted Answer · 2010-10-27 15:44:59Z

It's not a bad thing to use the if @object.save pattern. However, if you are doing exactly the same for all your actions on your controller, you can define a rescue_from action.

Something like

class MyController < ActionController::Base rescue_from ActiveRecord::RecordInvalid do render :action => edit end end

Yep, that was one of my options, but this kind of needs ! version, does not it? Do you know why scaffold does not go this way by default? It seems better to me.
Your and and @tadman both seem to complement each other, so I would accept both if I could, but unfortunately I had to chose one.

Collectives™ on Stack Overflow

Rails Newbie: Recommendations for error handling in controller

2 Answers 2

3 Comments

2 Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Related