Jinja2 macro for Twitter Bootstrap 3 alerts.

formhelpers.py

{% macro render_alert(category=None, dismissable=False, error=False,
                      message=None, link=None) -%}
    {% if not category and not error %}
        {% set category = 'success' %}
    {% elif error %}
        {% set category = 'danger' %}
    {% endif %}
    <div class="alert alert-{{ category }}
                {% if dismissable %} alert-dismissable{% endif %}">
        {% if dismissable %}
            <button type="button" class="close" data-dismiss="alert" aria-hidden="true">&times;</button>
        {% endif %}
        {% if category == 'success' %}
            <strong>Yay!</strong> {{ message|safe }}
        {% elif category == 'danger' %}
            <strong>Uh-oh!</strong> {{ message|safe }}
        {% elif category == 'info' %}
            <strong>Heads-up!</strong> {{ message|safe }}
        {% elif category == 'warning' %}
            <strong>Not so fast!</strong> {{ message|safe }}
        {% endif %}
        {% if link %}
            <a href="{{ link.href }}" class="alert-link">{{ link.message|safe }}</a>
        {% endif %}
    </div>
{%- endmacro %}

Use like this in your templates:

Import first:

{% from "formhelpers.py" import render_alert %}

Dismissable error message:

{{ render_alert(error=True, message='Incorrect login', dismissable=True) }}

Undismissable warning message:

{{ render_alert(category='warning', message='Be careful') }}

With a link:

{{ render_alert(error=True, message='Incorrect login', link={'href': '/forgot', 'message': 'Forgot password?'}) }}

and so on.