Question

I am passing these parameters to a controller:

{
  "utf8" => "✓",
  "authenticity_token" => "ersjaJ4/ieZelVifP/YpBHTJtiQ53HgO5KYjEdW0BlQ=",
  "transaction" => {
    "use_balance" => "1",
    "traces_attributes" => {
      "trace_ids" => ["6"],
      "6" => {
        "amount" => "12.0",
        "charge_id" => "6"
      }
    },
    "positive_balance" => "12",
    "property_id" => "2",
    "community_id" => "1"
  },
  "commit" => "Save Payment",
  "community_id" => "1",
  "property_id" => "2"
}

The controller#create then:

@payment = Transaction.new(params[:transaction])

Then the Transaction model:

belongs_to :property
belongs_to :community
attr_accessible :positive_balance

def traces_attributes=(params)
  #INSIDE HERE THE VALUES OF
  #params[:trace_ids] => ['6'] OK
  #BUT
  #self.possitive_balance => "" **NOT OK**
  #self.property_id => nil **NOT OK**
end

My hypothesis is that traces_attribute= is executed before positive_balance= and property_id

Can I change this?
Why is this failing?

Answer 1

The order of the assignments should be the same as the order of the params in the form, but I don’t think this is guaranteed.

A safer solution would be to only store the data in the traces_attributes= method, and access the other attributes later, for example in a before_save callback.