Setting a field to read-only in Rails after it's created

Question

Hi,

I'd like to protect a user-generated entry in a field after its initial creation.

I'm asking the user for a unique name when they set up a project, and I want to stop that being changeable after the creation.

Is there a way to do this in Rails? Can I set it as attr_accessible at first then switch it to to attr_protected?

Cheers

Answer 1

I would set it to :attr_protected and create a new "new" method:

def self.my_new(attributes = {})
  obj = new(attributes)
  obj.my_protected_attribute = attributes[:protected_attribute]
  obj
end

Answer 2

Hi Les

If I were to do this I'll do it in clients end using javascripts. Ex: create a javascript function which set the text box attribute to readonly after user enter the value. As i can see doing this is client side has 2 advantages

1 - you dont want to go through a server round to make lock the value 2 - You have the flexibility of allowing user to change the value if he/she wants (by clicking a button or something)

cheers

sameera

Answer 3

You could also, if you know the name of the attributes, handle this in the controller

class MyModel < ActiveRecord::Base
  attr_protected :super_cool
end

And then in the controller:

def create
  @my_model = MyModel.create(params[:my_model])
  @my_model.super_cool = params[:my_model][:super_cool] unless params[:my_model].nil?
  if @my_model.save
    ..
  else
    ..
  end
end

Answer 4

You can add custom validation method to your model:

# Project model
validate_on_update :forbid_changing_name

def forbid_changing_name
  errors[:name] = "can not be changed!" if self.name_changed?
end