relationships in models

rubyonrails-talk
1

I am new to rails and have got very confused with the above. It was working and then I made changes and it has gone downhill from there. And I was not taking regular backups.... I have moved slightly outside of the conventions but it is not unknown for a record type to be refered in another record in several fields - users being a good example. My schema file.   create_table "messages", :force => true do |t|     t.integer "from_user", :null => false     t.integer "to_user", :null => false     t.text "message"     t.datetime "created_at"     t.datetime "updated_at"   end

  add_index "messages", ["from_user"], :name => "fk_messages_from_users"   add_index "messages", ["to_user"], :name => "fk_messages_to_users"

  create_table "users", :force => true do |t|     t.string "user_id"     t.string "first_name"     t.string "surname" etc etc

My model files class Message < ActiveRecord::Base    belongs_to :user_from,               :class_name => "User",               :foreign_key => "from_user"

     belongs_to :user_to,               :class_name => "User",               :foreign_key => "to_user"

              validates_presence_of :message end class User < ActiveRecord::Base    has_many :user_from,               :class_name => "Message",               :foreign_key => "from_user"

     has_many :user_to,               :class_name => "Message",               :foreign_key => "to_user" etc etc I made changes to user looking at various google results. Previous I simply had class User < ActiveRecord::Base    has_many :messages etc etc

The controller action.   def my_messages   user = User.find(session[:userid])   @first_name = user.first_name   @messages = Message.paginate(:page => params[:page], :per_page => 10,          :conditions => ["from_user = ? or to_user = ?", session[:userid], session[:userid]],          :order => "created_at DESC")    @message = Message.new(params[:message])    @message.from_user = user    @message.to_user = User.find(1)    if request.post? and @message.save      @message = Message.new()      @messages = Message.paginate(:page => params[:page], :per_page => 10,          :conditions => ["from_user = ? or to_user = ?", session [:userid], session[:userid]],          :order => "created_at DESC")    end

And this is where I get confused. if I change the two lines above    @message.from_user = user    @message.to_user = User.find(1) # I know its hard coded but that is the least of my worries to    @message.from_user = session[:userid]    @message.to_user = 1 then I get expected results (ie value is 6) but message.from_user.first_name will give an undefined method error. If I use the former code then the value of from_user is 1 rather than 6. I have not a clue where it gets 1 from.

So, in summary, I have not got this. Any help appreciated.

Regards,

john

2

message.from_user.first_name will give an undefined method error.

message.from_user is an integer

message.user_from is a reference to a user, and user has a first_name method

3

Now I get it. The association name is the name used for the object. And I had the field name and the association which I had not realised but a least it emphasises the point. And by assigning the object to the this, I can then display values for the referred object. So my code is now class Message < ActiveRecord::Base    belongs_to :user_from_obj,               :class_name => "User",               :foreign_key => "from_user" etc etc   user = User.find(session[:userid])    @message = Message.new(params[:message])    @message.user_from_obj = user etc etc many thanks .