Tweaks to scaffolding for adding "child" rows by jgn on Thursday, August 30, 2007 in Technology and Rails

There are times when you need to use a bit of Rails scaffolding to get up and running and for various reasons you don't want to resort to ActiveScaffold or some other medium-weight strategy. All you want to do is provide the user a means to see a "master" row, and then allow for adding a row to a dependent ("child") table. Here we're talking about "the simplest thing that could possibly work." This example is for Rails 1.2.3.

Typically the recipe is going to be like so:

Add your scaffolds:

script generator/scaffold master Admin::Master
script generator/scaffold child Admin::Child

Edit your migrations to get your data model where you want it.

In master/show.rhtml, add ruby <%= link_to 'Add child', :controller => Admin::Child, :action => 'new', :id => @master.id %> <br/><br/>

In child/_form.rhtml, add ruby <%= hidden_field 'child', 'master_id', :value => params[:id] %>

That's essentially it. Now after adding a Master record, you click the scaffold's "show" link, and that view will give link to add a Child record with its foreign key set to the value of the Master for which you are adding the Child.

As soon as it gets complicated, though, go use ActiveScaffold.