Deal with active record not found exceptions when creating message. Some tidying of html. For some reason in rails 2.1.2 having a comment at the end of a line, in the view, means that the closing tag needs to be on the next line.

app/controllers/message_controller.rb

@@ -7,11 +7,13 @@ class MessageController < ApplicationController
   # Allow the user to write a new message to another user. This action also 
   # deals with the sending of that message to the other user when the user
   # clicks send.
+  # The user_id param is the id of the user that the message is being sent to.
   def new
     @title = 'send message'
+    @to_user = User.find(params[:user_id])
     if params[:message]
       @message = Message.new(params[:message])
-      @message.to_user_id = params[:user_id]
+      @message.to_user_id = @to_user.id
       @message.from_user_id = @user.id
       @message.sent_on = Time.now
    
@@ -23,6 +25,8 @@ class MessageController < ApplicationController
     else
       @title = params[:title]
     end
+  rescue ActiveRecord::RecordNotFound
+    render :action => 'no_such_user', :status => :not_found
   end
 
   # Allow the user to reply to another message.
@@ -33,7 +37,7 @@ class MessageController < ApplicationController
     @user_id = message.from_user_id
     render :action => 'new'
   rescue ActiveRecord::RecordNotFound
-    render :nothing => true, :status => :not_found
+    render :action => 'no_such_user', :status => :not_found
   end
 
   # Show a message
@@ -43,7 +47,7 @@ class MessageController < ApplicationController
     @message.message_read = true if @message.to_user_id == @user.id
     @message.save
   rescue ActiveRecord::RecordNotFound
-    render :nothing => true, :status => :not_found
+    render :action => 'no_such_user', :status => :not_found
   end
 
   # Display the list of messages that have been sent to the user.
@@ -82,5 +86,7 @@ class MessageController < ApplicationController
         redirect_to :controller => 'message', :action => 'inbox', :display_name => @user.display_name
       end
     end
+  rescue ActiveRecord::RecordNotFound
+    render :action => 'no_such_user', :status => :not_found
   end
 end

app/views/message/_message_summary.rhtml

@@ -1,9 +1,10 @@
-<% this_colour = cycle('lightgrey', 'white') # can only call once for some dumb reason %>
+<% this_colour = cycle('lightgrey', 'white') # can only call once for some dumb reason 
+%>
 
 <tr class="inbox-row<%= "-unread" if not message_summary.message_read? %>">
-  <td class="inbox-sender" bgcolor='<%= this_colour %>'><%= link_to h(message_summary.sender.display_name), :controller => 'user', :action => message_summary.sender.display_name %></td>
-  <td class="inbox-subject" bgcolor='<%= this_colour %>'><%= link_to h(message_summary.title), :controller => 'message', :action => 'read', :message_id => message_summary.id  %></td>
-  <td class="inbox-sent" bgcolor='<%= this_colour %>'><%= message_summary.sent_on %></td>
+  <td class="inbox-sender" bgcolor="<%= this_colour %>"><%= link_to h(message_summary.sender.display_name), :controller => 'user', :action => message_summary.sender.display_name %></td>
+  <td class="inbox-subject" bgcolor="<%= this_colour %>"><%= link_to h(message_summary.title), :controller => 'message', :action => 'read', :message_id => message_summary.id  %></td>
+  <td class="inbox-sent" bgcolor="<%= this_colour %>"><%= message_summary.sent_on %></td>
   <% if message_summary.message_read? %>
     <td><%= button_to 'Mark as unread', :controller => 'message', :action => 'mark', :message_id => message_summary.id, :mark => 'unread' %></td>
   <% else %>

app/views/message/_sent_message_summary.rhtml

@@ -1,7 +1,8 @@
-<% this_colour = cycle('lightgrey', 'white') # can only call once for some dumb reason %>
+<% this_colour = cycle('lightgrey', 'white') # can only call once for some dumb reason
+%>
 
 <tr class="inbox-row">
-  <td class="inbox-sender" bgcolor='<%= this_colour %>'><%= link_to h(sent_message_summary.recipient.display_name), :controller => 'user', :action => sent_message_summary.recipient.display_name %></td>
-  <td class="inbox-subject" bgcolor='<%= this_colour %>'><%= link_to h(sent_message_summary.title), :controller => 'message', :action => 'read', :message_id => sent_message_summary.id  %></td>
-  <td class="inbox-sent" bgcolor='<%= this_colour %>'><%= sent_message_summary.sent_on %></td>
+  <td class="inbox-sender" bgcolor="<%= this_colour %>"><%= link_to h(sent_message_summary.recipient.display_name), :controller => 'user', :action => sent_message_summary.recipient.display_name %></td>
+  <td class="inbox-subject" bgcolor="<%= this_colour %>"><%= link_to h(sent_message_summary.title), :controller => 'message', :action => 'read', :message_id => sent_message_summary.id  %></td>
+  <td class="inbox-sent" bgcolor="<%= this_colour %>"><%= sent_message_summary.sent_on %></td>
 </tr>

app/views/message/new.rhtml

@@ -1,7 +1,4 @@
-<% user_id = params[:user_id] || @user_id %>
-<% display_name = User.find_by_id(user_id).display_name %>
-
-<h2>Send a new message to <%= h(display_name) %></h2>
+<h2>Send a new message to <%= h(@to_user.display_name) %></h2>
 
 <% if params[:display_name] %>
 <p>Writing a new message to <%= h(params[:display_name]) %></p>  
@@ -10,7 +7,7 @@
 
 <%= error_messages_for 'message' %>
 
-<% form_for :message, :url => { :action => "new", :user_id => user_id } do |f| %>
+<% form_for :message, :url => { :action => "new", :user_id => @to_user.id } do |f| %>
   <table>
     <tr valign="top">
       <th>Subject</th>