{% %} and {{ }} in Django

Question

I am learning Django and came across 2 sets of special characters that I haven't seen used like this before. I can guess what they are used for in the examples, but don't understand their scope.

They are:

• {% if registered %}
• {{ user_form.as_p }}

I added the if registered and user_form.as_p in for context. I am only concerned with the {% %} and {{ }} parts of it.

• Are these only used in Django or are they also used in Python?
• What is the meaning of each?
• Are there other similar sets of characters?

Answer 1

{% if registered %} is a Django template tag that checks if the variable registered is True or has a truthy value. If registered is True, the code inside the if block will be executed, otherwise it will be ignored.

The code {{ user_form.as_p }} is also a Django template tag that renders a form object called user_form as a series of HTML paragraphs (<p> tags), with each form field wrapped in a label tag (<label>). This code is typically used to display the form on a web page, allowing users to enter data and submit it to the server.

Putting the two together, the code {% if registered %}{{ user_form.as_p }}{% endif %} will only render the form if the registered variable is True. If the registered is False or has a false value, the form will not be rendered on the page. This is a common pattern used in Django templates to conditionally display content based on user input or application state.

Answer 2

These are special tokens that appear in django templates. You can read more about the syntax at the django template language reference in the documentation.

{{ foo }} - this is a placeholder in the template, for the variable foo that is passed to the template from a view.

{% %} - when text is surrounded by these delimiters, it means that there is some special function or code running, and the result of that will be placed here. It is used when the text inside is not passed to the template from the view, but rather a function or feature of the template language itself that is being executed (like a for loop, or an if conditional). You can create your own extensions to the template language, which are called template tags.

{{ foo|something }} - this is yet another syntax you may come across. The |something is a template filter. It is usually for transforming the result of the item on the left of the | symbol. For example {{ foo|title }}.

You can read more about tags and filters which are referred to as template builtins in the documentation.

This syntax is not unique to django - many other template languages in Python (and some outside of Python) have adopted a similar syntax.

The Python language doesn't have the same syntax, but it does have the concept of string templates which is a very simplified version of a template engine.

Answer 3

They are used in .html files aka templates. They are not python, they are part of the Django's template engine.

You use {% %} for sentences such as: if and for, or to call tags such as: load, static, etc.

And you use {{ }} to render variables in your template.

Answer 4

{% %} and {{ }} are part of Django templating language. They are used to pass the variables from views to template. {% %} is basically used when you have an expression and are called tags while {{ }} is used to simply access the variable.

For more information, I suggest have a look at :

https://docs.djangoproject.com/en/1.9/ref/templates/language/#variables