How can I call a method on my form controller from my view in Rails?

Question

Newbie to RoR. I can't grasp the concept of how to call a simple method on my form controller from my view. I want to collect 2 pieces of information form the view, call a method on the form controller that will retrieve a piece of information based on the parameters, and then display the piece of information on that same view or another one. Right now, I was trying to use a form controller instance variable to accomplish the displaying of the new piece of information--not sure how I will refresh the view to display it but that is a future hurdle. Right now, I can click my Submit button without getting any errors but it is clearly not hitting my form controller method. Here is my erb file for the view:

<h1>Enter Required Information</h1>

<%= form_tag (get_hotel_recommendation_path) do %>
  <%= label_tag(:name, "Name:") %>
  <%= text_field_tag(:name) %>
  <%= label_tag(:date, "Date (yyyy-mm-dd):") %>
  <%= text_field_tag(:date) %>
  <%= submit_tag("Submit") %><br><br>
  <%= label_tag(:recommendation, "Recommendation:") %>
  <%= @recommended_hotel_name %>
<% end %>

Here is my form controller code:

class RecommendHotelController < ApplicationController

  @recommended_hotel_name = ''

  def collect_info

  end

  def get_hotel_recommendation
    @recommended_hotel_name = Member.recommended_hotel_name( params[:name], params[:date] )
  end

end

I really just want a simple and easy way to do this--not necessarily the best. I just need a quick UI to demonstrate my model code. And I need to get it done soon.

New form controller code:

class RecommendHotelController < ApplicationController

  def collect_info
  end

  def get_hotel_recommendation
    redirect_to recommend_hotel_path
  end

  protected

    helper_method :recommended_hotel_name
    def recommended_hotel_name
      unless (params[:name].nil?)
        Member.recommended_hotel_name(params[:name], params[:date])
      end
    end

end

Answer 1

Once the controller hands over to the view, there's no going back to call additional methods. It is the controller's job to prepare everything the view might need in advance. Once inside the render phase, there's no way to call controller methods.

The exception to this is helper methods which can be called. You need to declare any methods you want to use within your view explicitly. As an example:

helper_method :get_hotel_recommendation
def get_hotel_recommendation
  # ...
end

Helper methods can also be located inside the associated helper module, and it's a good idea to put them there if they're used exclusively within views.

In your case, if you're using this only once, you should probably skip the assignment to an instance variable and just return the object in question. The view would look like:

<%= recommended_hotel_name %>

The adjusted controller method:

class RecommendHotelController < ApplicationController
protected
  helper_method :recommended_hotel_name
  def recommended_hotel_name
    Member.recommended_hotel_name(params[:name], params[:date])
  end
end

It's worth noting that declaring @recommended_hotel_name = '' in the class context is probably not what you intend. This creates a class variable, not an instance variable. Instance variables in controllers must be defined inside the primary action method or inside a before_filter method. Also remember that instance variables are nil by default, so there's no need to initialize them to that first. An empty string and nil are equivalent when used within a view, everything inside <%= ... %> is converted to a string for you automatically.

Another thing to watch out for is leaving a space between a method name and its arguments. It should be form_tag(...) and not form_tag (...). Normally this does not make a difference, Ruby can be very lenient, but sometimes it can subtly alter the way the arguments are interpreted leading to a lot of confusion as you try to diagnose the problem. Stylistically speaking, only keywords like if, while and case have a space before the brackets as these are not method calls.

As to why your form isn't working, it's not clear. Those parameters should be submitted as you intend, but maybe you're not getting the right routing. Remember it's best to stick with the standard index, new, show, and edit names unless you're doing something exotic. In this case, you should probably define this as index if it shows more than one record or show if it's always one record.

Answer 2

You can get all the information from a form submit in the params array. However, from your example, I would advise to use: form_for instead of using separate form_tags.