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    copied!<p>I faced a similar situation. My solution may have performance issues in your scenario, it didn't for me but it's a low concurrent usage system, only 300 total users.</p> <p>What I did was go with one MEGA AJAX view/form! and use JavaScript to show/hide as needed. This technique requires that you NOT use the form tag helpers (i.e. text_field_tag instead of f.text_field) an YOU have to take control of the element names.</p> <p>So start out creating a single view with all of the forms you'll eventually need. You'll have to distinguish them so put each one in a div element with a unique ID. </p> <pre><code>&lt;%= form_for @mega, :remote=&gt;true do %&gt; &lt;div id='main_part'&gt; &lt;%= render :partial =&gt; "main_part", :object=&gt;@mega %&gt; &lt;/div &lt;div id='subpart1'&gt; &lt;%= render :partial =&gt; "subpart1" , :object=&gt;@foobar , :locals=&gt;{:id=&gt;@foobar.id} %&gt; &lt;/div &lt;div id='subpart2'&gt; &lt;%= render :partial =&gt; "subpart2" , :object=&gt;@barfoo , :locals=&gt;{:id=&gt;@barfoo.id} %&gt; &lt;/div &lt;% end %&gt; </code></pre> <p>An example of the form partials, taking care to distinguish the submit buttons:</p> <pre><code>&lt;%= label_tag "main_part[name]" ,"Name" %&gt; &lt;%= text_field_tag "main_part[name]" , main_part.name %&gt; &lt;%= submit_tag "UPDATE", :name=&gt;'main_part' %&gt; &lt;%= hidden_tag_field "subpart1_id" , id %&gt; &lt;%= label_tag "subpart1[city]" ,"City" %&gt; &lt;%= text_field_tag "subpart1[city]" , subpart1.city%&gt; &lt;%= submit_tag "ADD", :name=&gt;'subpart1' %&gt; </code></pre> <p>So now you'd need a mega controller, because this one form posts to a single controller action. This controller would look like a regular controller for your top level model only, but it will need to do the housekeeping for ALL the models.</p> <p>That controller action has to figure out which submit button was clicked, i.e.</p> <pre><code>def update if params[:main_part] # since I controlled the parameter naming I know what's in params[:main_part] # which is main_part[:name] @mega = MainThing.find(params[:id]) @mega.attributes = params[:main_part] @mega.save # only for main_part is the id valid, in every other case you have to # manually extract the id elsif params[:subpart1] @subpart1_id = params[:subpart1_id] @foobar = FooBar.find(@subpart1_id) @foobar.attrubutes = params[:subpart1] @foobar.save else end end </code></pre> <p>Since the mega form is remote=>true, you need to create a javascript file that will reload all your form partials, so in app/views/megas/update.js.erb:</p> <pre><code>$('#main_part').html('&lt;%= escape_javascript(render :partial=&gt; "main_part", :object=&gt;@mega) %&gt;'); $('#subpart1').html('&lt;%= escape_javascript(render :partial=&gt; "subpart1", :object=&gt;@foobar :locals=&gt;{:id=&gt;@foobar.id) %&gt;'); </code></pre> <p>Now here is where the performance issues comes in. If you notice, if I run that javascript, it will expect all these instance variables be defined, so the various partial will render refreshing any select tags that got new values as a result of the update. In my case I just load them all up, in a before filter, i.e.</p> <pre><code>class MegaController &lt; ApplicationController before_filter :load, :only=&gt;[:edit] def load @mega = Mega.find(params[:id]) @foobar = @mega.foobar @barfoo = @foobar.barfoo end </code></pre> <p>But you could also NOT to that, and instead create individual javascript files and render them specifically in the controller, i.e.</p> <pre><code>def update if params[:main_part] # do whatever... render :action=&gt;'update_set1', :handler=&gt;[:erb], :formats=&gt;[:js] elsif params[:subpart1] # do whatever render :action=&gt;'update_set1', :handler=&gt;[:erb], :formats=&gt;[:js] elsif params[:subpart2] # do whatever render :action=&gt;'update_set2', :handler=&gt;[:erb], :formats=&gt;[:js] end end </code></pre> <p>The file app/views/mega/update_set1.js.erb would only update the partials affected by an update to @mega or @foobar, update_set2.js.erb would update partials affected by an update to @barfoo.</p> <p>Last point, you're form is remote=>true, how do you exit? Assuming you have:</p> <pre><code>&lt;%= submit_tag 'Cancel', :name=&gt;'cancel' %&gt; </code></pre> <p>Then in a controller you'd do something like:</p> <pre><code> def update if params[:cancel] render :js=&gt; "window.location = '/'" else # whatever.... end end </code></pre> <p>The last step is to add javascript to show/hide the form divs as needed, an exercise left to the reader....</p> <p>UPDATE</p> <pre><code>class Mega &lt; ActiveRecord::Base def self.get_param_name self.class.name end def self.get_id_name "#{self.class.name}_id" end end class MyModel &lt; Mega end </code></pre> <p>then in a mega controller:</p> <pre><code>def edit @mymodel = MyModel.find(params[MyModel.get_id_name]) end </code></pre>
 

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