Pagination in Flask does not work

Question

I have a view:

@app.route('/', methods=['GET', 'POST'])
@app.route('/index', methods=['GET', 'POST'])
@app.route('/index/<int:page>', methods=['GET', 'POST'])
def index(page=1):
 posts = Post.query.paginate(page, 3, False).items
 return render_template('index.html', posts=posts)

Code template:

 {% if posts %}
 <ol>
 {% for post in posts %}
 <li>{{ post.title }}</li> | {{ post.text }} | {{ post.time }}</li>
 {% endfor %}
 </ol>
 {% else %}
 <h2>There is no posts</h2>
 {% endif %}
 {% if posts.has_prev %}<a href="{{ url_for('index', page=posts.prev_num) }}"><< Newer posts</a>{% else %}<< Newer posts{% endif %} |
 {% if posts.has_next %}<a href="{{ url_for('index', page=posts.next_num) }}">Older posts >></a>{% else %}Older posts >>{% endif %}

The problem is that it does not generate me a link to see more posts.

Answer 1

.has_prev and .has_next are attributes of the Pagination instance, but you are discarding that instance. All you passed into the view is the Pagination.items attribute. You are then trying to still access the .has_prev and .has_next attributes on the items list, and those attributes do not exist there so Jinja2 resolves those as undefined.

Pass in the Pagination instance:

posts = Post.query.paginate(page, 3, False)
return render_template('index.html', posts=posts)

and adjust your template:

{% if posts.items %}
 <ol>
 {% for post in posts.items %}
 <li>{{ post.title }}</li> | {{ post.text }} | {{ post.time }}</li>
 {% endfor %}
</ol>
{% else %}
 <h2>There is no posts</h2>
{% endif %}
{% if posts.has_prev %}<a href="{{ url_for('index', page=posts.prev_num) }}"><< Newer posts</a>{% else %}<< Newer posts{% endif %} |
{% if posts.has_next %}<a href="{{ url_for('index', page=posts.next_num) }}">Older posts >></a>{% else %}Older posts >>{% endif %}