Rails: How do you create a new nested resource?

In my app, Users have Conversations, and Conversations have Messages. A Message belongs both to a User (as an author) and to a Conversation.

I want to create a new Message. This is the code I'm using right now in MessagesController.

def new
  @user = current_user #currently logged in user
  @conversation = Conversation.find(params[:id])
  @message = @conversation.messages.build
end

def create
  @conversation = Conversation.find(params[:conversation_id])
  @message = @conversation开发者_如何学编程.messages.build(params[:message])
  if @message.save
    redirect_to username_conversation(current_user, @message.conversation)
  else
    redirect_to root_url
  end
end

params[:message] contains the message content ("content" => "I'm Spartacus").

This isn't working (probably because I'm not specifying the user/author when creating a new Message?). How do I make this work the Rails way?

Thanks.

You need to set the user manually. Only one property can be set using the short methods provided by Rails.

def new
  @user = current_user #currently logged in user
  @conversation = Conversation.find(params[:id])
  @message = @conversation.messages.build
  @message.user = user
end

def create
  @conversation = Conversation.find(params[:conversation_id])
  @message = @conversation.messages.build(params[:message])
  @message.user = current_user
  if @message.save
    redirect_to username_conversation(current_user, @message.conversation)
  else
    redirect_to root_url
  end
end