如何选择一年中的第二个月并在symfony doctrine form dateType中显示正确的日期（28或29）

How could I select the second month of the year and display the correct day, 28 or 29 based on leap year, in symfony doctrine form dateType?

The picture below is the form I use form theme to customize. It's display well but the problem is when I select the second month it still let me select the day bigger than 29. Could I validate it in Symfony? Or has other ways to do that?

In doctrine form:

$builder
    ->add('startDate', DateType::class, [
        'format' => 'yyyy-MM-dd',
    ])
    ->add('endDate', DateType::class, [
        'format' => 'yyyy-MM-dd',
    ]);

In views form theme(twig)

{% block date_widget %}
     {% spaceless %}
        {% if widget == 'single_text' %}
            {{- block('form_widget_simple') -}}
        {% else %}
            {% set attr = attr|merge({class: (attr.class|default('') ~ ' form-inline')|trim}) %}
            {% if datetime is not defined or not datetime %}
                <div {{ block('widget_container_attributes') }}>
            {%- endif %}
                {{ date_pattern|replace({
                    '{{ year }}':  form_widget(form.year, {'attr': {'id': 'year', 'name': 'year', 'class': 'form-control'}}),
                    '{{ month }}': form_widget(form.month, {'attr': {'id': 'month', 'name': 'month', 'class': 'form-control'}}),
                    '{{ day }}':   form_widget(form.day, {'attr': {'id': 'day', 'day': 'day', 'class': 'form-control'}}),
                })|raw }}
            {% if datetime is not defined or not datetime %}
                </div>
            {%- endif -%}
        {% endif %}
    {% endspaceless %}
{% endblock date_widget %}

In view

<div class="col-xs-12" style="margin-top:10px">
    <div class="form-inline">
        <div class="form-group">
             <label>Effective Time: </label>
        </div>
        <div class="form-group">
             {{ form_widget(form.startDate) }}
        </div>
        <div class="form-group">
            <label>  -  </label>
        </div>
        <div class="form-group">
            {{ form_widget(form.endDate) }}
        </div>
    </div>
</div>

Do you have to implement the form entirely by yourself? There are client-side solutions like: http://amsul.ca/pickadate.js. Just google "javascript datepicker".

After that, you should validate the date serverside aswell: You could use php's checkdate function: var_dump(checkdate(12, 31, 2000)); http://php.net/manual/en/function.checkdate.php