<form method="post" action>
    {{ form.csrf_token() }}

    {% for field in form if field.widget.input_type != 'hidden' %}
        {# apply classes depending on field #}
        {% set field_classes = 'form-control' %}
        {% if field.type == "SelectField" %}
            {% set field_classes = field_classes + " custom-select" %}
        {% endif %}

        <div class="form-group {% if field.errors|length > 0 %}has-danger{% endif %}">
            {% if field.type == "SubmitField" %}
                {# button #}
                {% if field.render_kw['class']|length > 0 %}
                    {{ field(value=field.label.text) }}
                {% else %}
                    {{ field(class='btn btn-success btn-block', value=field.label.text) }}
                {% endif %}
            {% elif field.type == "BooleanField" %}
                {# checkbox #}
                <label class="custom-control custom-checkbox">
                    {{ field(class="custom-control-input") }}
                    <span class="custom-control-indicator"></span>
                    <span class="custom-control-description">
                        {{ field.label.text }}
                        {% if field.flags.required %}
                            <span class="text-danger">*</span>
                        {% endif %}</span>
                </label>
                {% if field.description %}
                    <span class="text-muted" style="font-size: 9pt;">{{ field.description|safe }}</span>
                {% endif %}
            {% else %}
                {# reszta #}
                <label class="form-control-label" for="{{ field.name }}">
                    {{ field.label.text }}
                    {% if field.flags.required %}
                        <span class="text-danger">*</span>
                    {% endif %}
                    {% if field.description %}
                        <span class="text-muted" style="font-size: 9pt;">{{ field.description|safe }}</span>
                    {% endif %}
                </label>

                {% if field.render_kw['placeholder']|length > 0 %}
                    {{ field(class=field_classes, required=field.flags.required) }}
                {% else %}
                    {{ field(class=field_classes, required=field.flags.required, placeholder=field.label.text) }}
                {% endif %}
            {% endif %}
            {% for err in field.errors %}
                <div class="form-control-feedback">Ups! {{ err }}</div>
            {% endfor %}
        </div>
    {% endfor %}
</form>