Cannot pass id field to ActiveRecord

rubyonrails-talk
1

Dear all

I have a dummy question. The model code as follow:

class User < ActiveRecord::Base   set_primary_key "username" end

In script/console

user = {:username => "123", :display_name => "345"} => {:username=>"123", :display_name=>"345"}

a = User.new(user) => #<User username: nil, display_name: "345">

Why the username field is nil instead of "123"? I also tried {:id=>"123", :display_name=>"345"}, still not work

But there is no problem when I do the following a.username = "123" or a.id = "123" a.save

Please help. Thank you very much.

Valentino

2

user = {:username => "123", :display_name => "345"} => {:username=>"123", :display_name=>"345"}

a = User.new(user) => #<User username: nil, display_name: "345">

Why the username field is nil instead of "123"? I also tried {:id=>"123", :display_name=>"345"}, still not work

But there is no problem when I do the following a.username = "123" or a.id = "123" a.save

Please help. Thank you very much.

Because the primary key is protected from mass assignment.

Fred

3

Frederick Cheung wrote:

But there is no problem when I do the following a.username = "123" or a.id = "123" a.save

Please help. Thank you very much.

Because the primary key is protected from mass assignment.

Fred

Thank you for your reply

Is that the only way to insert record like this? a = User.new a.username = "123" a.display_name = "456" a.save The code is not elegant then.

In this situation, It is not allowed to use the scaffold code in controller like this? It is not convenient if the primary key is not the default "id" field. @user = User.new(params[:user])

Thanks Valentino

4

you just have to set the primary key manually.   @user = User.new(params[:user])   @user.username = params[:username]   @user.save

however for security reasons i would not advise to use mass-assignment for user-creation anyways. there could be stuff like that in there:   >> params[:user][:is_admin]   => "1"

5

No, you can do this:

a = User.new(:display_name => "456") do |u|        u.id = 123      end a.save # or use .create in the first place rather than .new

However, if you have 'username' as the primary key, I'd strongly suggest that you reconsider that and follow the more conventional auto-incrementing integer primary key. Unless you have to deal with the structure of a legacy database, you'll save yourself a lot of trouble.

-Rob

Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com