Phoenix.HTML.Form date_select/3 for optional date
<h2>The problem</h2>

<p>I have a form where I have a field for an application date. This value is optional, as it can be provided at a later time (i.e. it is not necessarily present when the form is saved).</p>

<p>Using <code>date_select/3</code>, I'm unable to find a simple way to have this value be optional. Even if <code>default: nil</code> is provided as an option, the current date is filled in the fields. This is not the desired behavior, as when the user saves the form the value would be updated also.</p>

<h2>What I'd like</h2>

<p>A field to enter a date, with the possibility of leaving it blank (which would be the default behavior).</p>

<h2>What I've got so far</h2>

<p>You can get a date field for an optional value using the builder option and using empty prompts:</p>

<pre><code>&lt;%= date_select f, :applied_on, builder: fn b -&gt; %&gt;
    Date: &lt;%= b.(:day, [prompt: ""]) %&gt;.&lt;%= b.(:month, [prompt: ""]) %&gt;.&lt;%= b.(:year, [prompt: ""]) %&gt;
&lt;% end %&gt;
</code></pre>

<p>Isn't there a better, more elegant way to handle optional dates?</p>