Ruby on rails action code could be shorter So I have this code that i use for addition of funds to a certain item. 

def addFund
    fund=params[:fund]

    if(fund.to_i&gt;0)
      @fund=fund
      if(@item.fund+fund.to_f&gt;@item.price) #the fund added should be less than price-current fudn
        respond_to do |format|

         format.html { redirect_to @item, error: 'Fund amount should not exceed price difference' }
         format.json {render :json =&gt;{:status =&gt;0, 
          :error=&gt;"Fund amount cannot be greater than price difference  "}}
        end
        else
          #Finally do the addition
          @item.fund=@item.fund+fund.to_f
          @item.save
         respond_to do |format|

         format.html { redirect_to @item, success: 'Fund  added' }
         format.json {render :json =&gt;{:status =&gt;1, 
          :error=&gt;"Done"}}
        end
      end
    else
       respond_to do |format|
         format.html { redirect_to @item, error: 'No money specified.' }
         format.json {render :json =&gt;{:status =&gt;0, 
          :error=&gt;"Money not specified"}}
        end
    end

  end


So this is how it works:

First we check if the fund(POST ParameteR) is non zero fund.to_i&gt;0 and respond accordingly giving an error message if it isn't

@item.fund = the current funding the item has

@item.price =  the price of item

fund = the fund to be added(POST)

fund must be less than @item.price-@item.fund  since there is no point in accepting funds greater than the price, the item can already be bought

Then  finally if all this works, then we add the funds to the item and show him a message. 

So that's pretty much it. I am thinking there has to be a way of clubbing the responses and replying at one time. I have no idea how respond_to actually works. Ruby has blocks that you won't find in java or C++ or PHP
A lot of these logic could be moved to model. Rails provides lot of helpers for validation in your model. 

class Item
  validate :fund_vs_price, :fund_greater_than_zero


  def fund_vs_price
    errors.add(:fund, "Fund amount should not exceed price difference") if fund &gt; price
  end

  def fund_greater_than_zero
    errors.add(:fund, "No money specified.")
  end

  #overriding setter to do a sum every time it is assigned a value
  def fund=(value)
    write_attribute(:fund, fund.to_f + value)
  end
end


With that, the controller becomes really simple.

def addFund
    @item.fund = prams[:fund]
    if @item.save
       respond_to do |format|

         format.html { redirect_to @item, success: 'Fund  added' }
         format.json {render :json =&gt;{:status =&gt;1,
          :error=&gt;"Done"}}
       end
    else
      respond_to do |format|

       format.html { redirect_to @item, error: @item.errors[:fund].join("\n") }
       format.json {render :json =&gt;{:status =&gt;0,
        :error=&gt; @item.errors[:fund].join("\n")}}
      end
    end
  end


If your model becomes too big to maintain, you can always use ActiveSupport concerns to separate it out into different modules. For eg, you could move everything related to validation into a separate module.

There might be some logical errors in the above code since its not tested. But it will give you an idea