Can a WTForms BooleanField have a custom value?
<p>I would like to use WTForms (actually Flask-WTF) to generate this:</p>

<pre><code>&lt;input id="attr" name="attr" type="checkbox" value="ALL"&gt; Include all attributes
</code></pre>

<p>but if there is any way to specify a value as part of BooleanField, I cannot find it.  If I specify:</p>

<pre><code>class MyForm(Form):
    attr = BooleanField('attr', default=False, description="Include all attributes")
</code></pre>

<p>and render it in the template:</p>

<pre><code>{{ form.attr }} {{ form.attr.description }}
</code></pre>

<p>then I get</p>

<pre><code>&lt;input id="attr" name="attr" type="checkbox" value="y"&gt; Include all attributes
</code></pre>

<p>BooleanField doesn't have a "choices" or "value" property to set.  Is there any way to force it to have a value of my choosing (e.g. <code>ALL</code>) instead of just <code>y</code> ?</p>