website/app/modules/backend/templates/page/edit.j2

{% extends "layout/backend.j2" %}
{% block content %}
<h1>Edit: {{ page.title }}</h1>
<form method="post">
    <div class="form-group">
        <label class="text-normal text-dark">title</label>
        <input type="text" class="form-control" name="title" placeholder="title" value="{{ page.title }}">
    </div>
    <div class="form-group">
        <label class="text-normal text-dark">Source</label>
        <textarea class="form-control" name="source">{{ page.source }}</textarea>
    </div>
    <div class="form-group">
        <label class="text-normal text-dark">Parent</label>
        <select class="form-control" name="parent_id">
            <option></option>
            {% for parent_page in pages %}
            {% if parent_page.id == page.parent_id %}
            <option value="{{ parent_page.id }}" selected>{{ parent_page.title }}</option>
            {% else %}
            <option value="{{ parent_page.id }}">{{ parent_page.title }}</option>
            {% endif %}
            {% endfor %}
        </select>
    </div>
    <div class="form-group pull-right">
        <button class="btn btn-primary">Save</button>
    </div>
</form>
<p>{{ page.content() }}</p>
{% endblock %}