xppl/app/templates/add_book.html

{% extends 'base.html' %}

{% block main %}
<div class="container">
  <h1 class="page-header">Add Book</h1>
  {% with messages = get_flashed_messages() %}
    {% if messages %}
      <div class="alert alert-danger">
        <ul>
        {% for message in messages %}
          <li>{{ message }}</li>
        {% endfor %}
        </ul>
      </div>
    {% endif %}
  {% endwith %}
  <form method="POST" action="{{ url_for('add_book') }}" enctype=multipart/form-data>
    {{ form.csrf_token }}
    <div class="form-group">{{ form.title.label }} {{ form.title(size=20, class="form-control") }}</div>
    <br>
    <div data-toggle="fieldset" id="phone-fieldset">
         {{ form.author.label }}  <button type="button" data-toggle="fieldset-add-row"
                                          data-target="#phone-fieldset">+</button>
        <table>
            <tr>
                <th></th>
                <th></th>
            </tr>
            {% for author in form.author %}
                <tr data-toggle="fieldset-entry">
                    <td>{{ author.author_name }}</td>
                    <td><button type="button" data-toggle="fieldset-remove-row" id="phone-{{loop.index0}}-remove">-</button></td>
                </tr>
            {% endfor %}
        </table>
    </div>
<br>
<div class="form-group">{{ form.tag.label }} {{ form.tag(size=20, class="form-control") }}</div>
    {{ form.file }}
    <button type="submit" class="btn btn-primary">Upload</button>
</form>

</div>
{% endblock %}