 <p>In your view code for the 'new' action use FormHelper tags that reference the same model as your create action eg.</p> <pre><code>&lt;%= text_field :user, :login %&gt; </code></pre> <p>Then in your create action, use a model instance with the same name:</p> <pre><code>@user = User.new # detect error, redirect to 'new' </code></pre> <p>The FormHelper will use the value of this instance if it is available.</p>