How do I determine the "source" action for conditionally rendering error actions and validation messages?

rubyonrails-talk
1

I have a model called Stock.rb. I created an additional action, called dispense, in the controller so that I could render two different views based on the type of data entry being done. The "new" action is used for "adding stock" and the "dispense" action is used for "dispensing stock."

They are very similar, but use different form partials to remove fields that could potentially cause confusion. Both actions use the "create" action when submitted.

Stock.rb contains validates_presence_of :medicine_id, :route_id

stocks_controller.rb contains

  def create     @stock = Stock.new(params[:stock])     @routes = Route.find(:all, :capitalize, :order => :name)     @medicines = Medicine.find(:all, :capitalize, :order => :name)     if @stock.save       flash[:notice] = "Success | Sucesso | Éxito | Réussi"       redirect_to(:back)     else       flash[:error] = "You must select a medicine and a route."       redirect_to(:back)       #render :action => 'new'     end   end

Each of the form partials contains <%= f.error_messages %> so that validation errors are shown at the top of the form if the user fails to select a medicine or a route.

The problem I'm having is that the validation error messages are only shown when using render. render :action => 'new' shows the error messages, but if the user comes to this from the "dispense" action, they are returned to the form for the "new" action, which is used for a different purpose.

I changed the code to redirect_to(:back), which returns the user to the proper form, but doesn't show the validation error message -- only the flash[:error] message that I inserted.

How do I either: 1) Detect which action/view/template sent the user to the create action, so that I can conditionally return them to the proper action using render?

or

2) Use redirect_to(:back) and still show the validation errors?

2

I have a model called Stock.rb. I created an additional action, called dispense, in the controller so that I could render two different views based on the type of data entry being done. The "new" action is used for "adding stock" and the "dispense" action is used for "dispensing stock."

They are very similar, but use different form partials to remove fields that could potentially cause confusion. Both actions use the "create" action when submitted.

Not answering your question directly, but you might considered an alternative approach, which is to use the 'new' action for both adding and dispensing, with a parameter in the url to indicate which is required (or possibly you can already tell which action is required by examining the existing parameters). You say the two actions are very similar so this might make for less code and would solve the problem you are having with the render I think.

Colin

3

The RESTful way is to have a "dispense_stock" controller - which has its own methods.

The cheaty (smelly) way is to put a hidden field in the form or an extra querystring parameter with with the value "new" or "dispense", and check the params hash for the value.

4

Whether this is smelly or not really depends on how similar the two actions are. As I understand it they both create a new record in the same table, so it _could_ be virtually (or even completely) odour free to use the same action and determine the details of what to do based on parameters (it may not even be necessary to add a new parameter, it may be implicitly clear from existing parameters). On the other hand I agree that route could cause an offensive effluvia to exuded. It all depends on the detail.

Colin

5

Don't get me wrong - I wasn't saying *don't* use a hidden param - I was suggesting it as a perfectly acceptable option... it's just that I know the REST police will jump on you if you're not careful. To be honest, in lots of situations, the quick, easy (dirty?) way is best *because* it's quick and easy.

And you're right; it may be perfectly possible to design the form to use the same, restful action, and please everybody :slight_smile:

6

Both of your comments were helpful and led to me to consider how I could check the form elements to determine where to send them upon validation failure. It ain't restful and probably smells quite unpleasant, but it seems to work. I'll keep an eye on it and improve the structure once I've straightened up some other issues. Thanks!