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POWhere should calculation logic go in a Rails app?
 

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  1. POWhere should calculation logic go in a Rails app?
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    <p>I have an app that models a House. The House has_many Rooms, Rooms has_many Lights and Small_appliances, etc. I also have a controller called Calculator that is how the app is accessed. Data is added to the house (and its rooms) using the Calculator controller. Then a report is generated, which is located at app/views/calculator/report.html.erb.</p> <p>My question is where should all the calculations and logic for the report go? Currently I have it all in the view, with some things in calculator_helper. Normally this would go in the model, right? But Calculator doesn't have a model that was generated. What is the standard for this?</p> <p>Here is the calculator controller.</p> <pre><code>class CalculatorController &lt; ApplicationController def index end def save_house @house = House.new(params[:house]) respond_to do |format| if @house.save format.html { render :action =&gt; 'add_rooms', :id =&gt; @house } format.xml { render :xml =&gt; @house, :status =&gt; :created, :location =&gt; @house } else format.html { render :action =&gt; 'index' } format.xml { render :xml =&gt; @house.errors, :status =&gt; :unprocessable_entity } end end end def add_rooms @house = House.find(params[:id]) @rooms = Room.find_by_house_id(@house.id) rescue ActiveRecord::RecordNotFound logger.error("Attempt to access invalid house #{params[:id]}") flash[:notice] = "You must create a house before adding rooms" redirect_to :action =&gt; 'index' end def add_room @room = Room.new(params[:room]) @house = @room.house respond_to do |format| if @room.save flash[:notice] = "Room \"#{@room.name}\" was successfully added." format.html { render :action =&gt; 'add_rooms' } format.xml { render :xml =&gt; @room, :status =&gt; :created, :location =&gt; @room } else format.html { render :action =&gt; 'add_rooms' } format.xml { render :xml =&gt; @room.errors, :status =&gt; :unprocessable_entity } end end rescue ActiveRecord::RecordNotFound logger.error("Attempt to access invalid house #{params[:id]}") flash[:notice] = "You must create a house before adding a room" redirect_to :action =&gt; 'index' end def report flash[:notice] = nil @house = House.find(params[:id]) @rooms = Room.find_by_house_id(@house.id) rescue ActiveRecord::RecordNotFound logger.error("Attempt to access invalid house #{params[:id]}") flash[:notice] = "You must create a house before generating a report" redirect_to :action =&gt; 'index' end end </code></pre>
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    1. USRyan
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      1. POWhere should calculation logic go in a Rails app?
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    1. COPlease show us your Calculator class.
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      1. POWhere should calculation logic go in a Rails app?
      1. USRyan Bigg
    2. COI like James's answer. Another question I think you should be asking yourself is why you're breaking from the convention - why is Calculator controller handling things that seemingly belong to the House controller? I'm not saying you doing it wrong, I'm just saying it's worth putting some more thought into.
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      1. POWhere should calculation logic go in a Rails app?
      1. USAndy Gaskell
    3. COGood point, Andy. Ryan, get the MODELS right before you start worrying about controllers and views. Using this approach you may discover that the correct place for all the calculations is the House model.
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      1. POWhere should calculation logic go in a Rails app?
      1. USJonathan Julian
 

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