Paging Query Results

If you have a lot of results, you may only want to show a certain number at a time, allowing the user to click next and previous links to see pages of data. This is sometimes called pagination, and uses the verb paginate.

Call SQLAlchemy.paginate() on a select statement to get a Pagination object.

During a request, this will take page and per_page arguments from the query string request.args. Pass max_per_page to prevent users from requesting too many results on a single page. If not given, the default values will be page 1 with 20 items per page.

page = db.paginate(db.select(User).order_by(User.join_date))
return render_template("user/list.html", page=page)

Showing the Items

The Pagination object’s Pagination.items attribute is the list of items for the current page. The object can also be iterated over directly.

<ul>
  {% for user in page %}
    <li>{{ user.username }}
  {% endfor %}
</ul>

Page Selection Widget

The Pagination object has attributes that can be used to create a page selection widget by iterating over page numbers and checking the current page. iter_pages() will produce up to three groups of numbers, separated by None. It defaults to showing 2 page numbers at either edge, 2 numbers before the current, the current, and 4 numbers after the current. For example, if there are 20 pages and the current page is 7, the following values are yielded.

users.iter_pages()
[1, 2, None, 5, 6, 7, 8, 9, 10, 11, None, 19, 20]

You can use the total attribute to show the total number of results, and first and last to show the range of items on the current page.

The following Jinja macro renders a simple pagination widget.

{% macro render_pagination(pagination, endpoint) %}
  <div class=page-items>
    {{ page.first }} - {{ page.last }} of {{ page.total }}
  </div>
  <div class=pagination>
    {% for page in pagination.iter_pages() %}
      {% if page %}
        {% if page != pagination.page %}
          <a href="{{ url_for(endpoint, page=page) }}">{{ page }}</a>
        {% else %}
          <strong>{{ page }}</strong>
        {% endif %}
      {% else %}
        <span class=ellipsis>…</span>
      {% endif %}
    {% endfor %}
  </div>
{% endmacro %}