title: rails ancestry nested form
body: <p>I've just started using Ancestry instead of awesome_nested_set and I would like to create a nested form so that I can create a parent account and many children accounts all in the one form. The problem seems to be that Ancestry doesn't allow you to create a child for a new parent.</p>
  
  <p>In awesome_nested_set I could do this in the rails console</p>
  
  <pre><code>a = Account.new
  a.children.build
  </code></pre>
  
  <p>When I type a.children I can see that new child in there even though my account parent hasn't been created yet.  This allowed me to display a form with the parent account and a few blank children, then on submit I would just ignore any blank children and create the whole lot.</p>
  
  <p>If I try and do the same using ancestry I get the following error:</p>
  
  <pre><code>a=Account.new
  a.children
  Ancestry::AncestryException: No child ancestry for new record. Save record before performing tree operations.
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/ancestry-1.2.4/lib/ancestry/instance_methods.rb:62:in `child_ancestry'
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/ancestry-1.2.4/lib/ancestry/instance_methods.rb:132:in `child_conditions'
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/ancestry-1.2.4/lib/ancestry/instance_methods.rb:136:in `children'
      from (irb):8
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.7/lib/rails/commands/console.rb:44:in `start'
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.7/lib/rails/commands/console.rb:8:in `start'
      from /home/map7/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.7/lib/rails/commands.rb:23:in `&lt;top (required)&gt;'
      from script/rails:6:in `require'
      from script/rails:6:in `&lt;main&gt;'
  </code></pre>
  
  <p>Is this a limitation of ancestry?
  I there a different way in which I could create a nested form using ancestry?</p>