Rails: set params but do not save : <p>What's the call to update a Rails record with new params, say, stored in a <code>hash</code> variable? This:</p>

<pre><code>@user.update(hash)
</code></pre>

<p>Will <em>save</em> the record, and since I want to put the call in a callback I don't want to save it, just prepare it to be saved correctly in the callback.</p>
