Multiple relations between two models

rubyonrails-talk
1

Well i thought about this issue too sometime ... and though i'm perfectly sure, this could work:

class Message < ActiveRecord::Base     belongs_to :sender, :foreign_key => "sender_id", :class => "User"     belongs_to :recipient, :foreign_key => "recipient_id", :class => "User" end

class User < ActiveRecord::Base    has_many :sentmessages, :foreign_key => "sender_id", :class => "Message"    has_many :rcvdmessages, :foreign_key => "recipient_id", :class => "Message" end

Then you *should* be able to do:

somevariable = message.sender somevariable = message.recipient

sentmsgs = user.sentmessages.find :all rcvdmsgs = user.rcvdmessages.find :all

So you practically reference the other class twice in both Models, but with different assiciation names (:sender <-> :recipient and :sentmessages <-> :rcvdmessages) and foreig keys ( sender_id <-> recipient_id). That creates two different associations with the same Model .... Someone please correct me if i'm wrong, i never tested it and only made my own thoughts from the rails docs

As i want to use soemthing like this myself soon, and IF the above is correct, i want to ask:

How is the best way to store the messages twice, so sender + recipient can both keep a copy and delete it whenever they want? Anyone got any idea?

2

Stewart wrote:

It's possible I am not as smart as they think I am.

class Message < ActiveRecord::Base   belongs_to :sender, :class_name => "User", :foreign_key => "user_id" end

the above line of code works fine for me when I do something like this...

<%= message.sender.full_alpha_name %>

however, when I am trying to create a new message with the following code...

  def sendmessage     @message = Message.new()

    @message.body = params[:message][:body]     @message.title = params[:message][:title]     @message.user_id = params[:message][:to]     @message.sender = current_user

    if @message.save       flash[:notice] = "Message Sent"       redirect_to :action => "index"     else       flash[:notice] = "Message not Sent"       redirect_to :action => "index"     end

  end

both the sender and the userid are set to the wrong values in the database. The sender always has a value of 0 in the database. The userid always has a value of 1.

Hang on. You should only have one column in your 'messages' table that relates to this join, and that column should be 'user_id'. You shouldn't have a column that called 'sender'.

As far as I can tell, that code should work fine, as long as current_user contains a saved User object.

When you say "The sender always has a value of 0 in the database. The userid always has a value of 1.", exactly which tables and columns are you talking about?

Chris

3

i think you got something twisted up. -> in the model, you say, the sender's foreign key is "user_id" -> in the controller, you assign the recipient ( params[:message][:to]) to the column "user_id"

From what you described i guess you have a foreign_key "sender" in your

message table that shold hold the ID of the user who sent the message, and the "user_id" filed should hold the name of the recipient of the message Your column naming could be more self-explanatory, e.g. use "recipient_id" as i suggested in my above post

i think, your :belongs_to sould look like this:

belongs_to :sender, :class_name "User", :foreign_key => "sender" belongs_to :recipient, :class_name "User", :foreign_key => "user_id"

but you should give some more info, like your exact table layout etc ... and what do the parameters hold? i guess params[:message][:to] hold the recipients name. well you need that user's id, not his name.

But im just guessing here, not enough insight and info....