Overriding the setter throws an error

[amingilani]

My values come with a lot of weird whitespace and padding so, as recommended by the docs I tried to override the accessors

  def price=(value)
    price = value.strip
    super(price)
  end
  
  def quantity=(quantity)
    quantity = quantity.strip
    super(quantity)
  end

This resulted in the following error:

     NoMethodError:
       super: no superclass method `price=' for #<Item:0x007faf30f2f620>
       Did you mean?  price

Is there a workaround for this? For the moment, i'm going to strip it in the controller, but this definitely feels like something the model should be doing.

[samstickland]

I think this will work if you prepend a module instead:

class MyRecord < ApplicationRecord
  module StripValues
    def price=(value)
      price = value.strip
      super(price)
    end
  
    def quantity=(quantity)
      quantity = quantity.strip
      super(quantity)
    end
  end

  prepend StripValues

The problem is that the setter methods are defined (via define_method) in your active record class itself, so there is no setter method in ActiveRecord::Base to call. Prepending a module however will prepend the method in your active record class, so when it calls super it will should call the right method.

That is, in the example above when MyRecord#price= is called, it will first invoke MyRecord::StripValues#price= and then when that calls super it will invoke MyRecord#price=

[amingilani]

Thank you!

[achernik]

There is also another way to handle this problem:

  alias price_from_monetize= price=

  def price=(value)
    price = value.strip
    self.price_from_monetize = price
  end

[rockwellll]

There is also another way to handle this problem:

  alias price_from_monetize= price=

  def price=(value)
    price = value.strip
    self.price_from_monetize = price
  end

I'm sorry but im dumbfounded and cant seem to understand how this works. Could you clarify? Thanks. @achernik

[dorianmariecom]

@rockwellll A common idiom is to do alias old_price= price= so you have an alias of the current price= method named old_price= that will be used later.

Then we override price=, do our custom code (the strip) and call the aliased method (the old_price= method, here named price_from_monetize=)

hope this helps