django: can I write python inside html template?

{% if request.sessi开发者_如何学编程on["user_name"] %}
<div class="abcd">user has username</div>
{% else %}
<div class="abcd">user doesn't has username</div>
{% endif %}

Is it illegal? There are errors:

TemplateSyntaxError at /users/register/submit

Could not parse the remainder: '['user_name']' from 'request.session['user_name']'

Django doc says :

Django template system is not simply Python embedded into HTML

Which means that you cannot write Python.

However talking about variables, the doc also says this :

Behind the scenes

Technically, when the template system encounters a dot, it tries the following lookups, in this order:

• Dictionary lookup
• Attribute lookup
• Method call
• List-index lookup

Which means that what you are trying is possible, but the right syntax is :

{% if request.session.user_name %}

Kindly note that you need to pass the variables that are to be evaluated in the following fashion.

Your python script

template_values = {
        'message': 'Invalid credentials, please try again'
            'users': users
}

path = os.path.join(os.path.dirname(__file__), 'login.html')
self.response.out.write(template.render(path, template_values))

The template file

{% ifequal users.name "name" %}
<div class="abcd">user has username</div>
{% endifequal %}

Please check the django template docs for further clarification based on the version that your using.