<div class="form-group {% if field.errors %}has-error{% endif %}">
    <div class="checkbox">
        <label>
            <input type="checkbox" name="{{ field.name }}" value="true"
            {% if field.value %}checked{% endif %}
            >
            {% if field.label %}{{ field.label }}{% endif %}
        </label>
    </div>
    {% if field.errors %}
        {% for error in field.errors %}<span class="help-block">{{ error }}</span>{% endfor %}
    {% endif %}
    {% if field.help_text %}
        <span class="help-block">{{ field.help_text|safe }}</span>
    {% endif %}
</div>
