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The Jinja2 Templating Language

Jinja2 plays the same role inside Microsoft Word docx templates that Mako plays inside the interview file.

Jinja was originally created as a templating language for Django. Docassemble's version of Jinja is not quite the same; it's a variation built for docx-template. It's useful to keep this in mind if you are trying to use an advanced feature and find that it doesn't work.

Jinja statements allow you to:

  1. Insert variables
  2. Use conditional text
  3. Use control structures to display repeated variables

Insert variables​

To insert a variable into your document, surround it with double curly braces, like this: {{ variable_name }}.

It's also possible to include Python code in the place of the variable name. For example, if you had assigned the value of my_variable as below:

my_variable = "lowercase name"

Then you could use the .capitalize() method of a string inside Jinja tags to make sure that it started with a capital letter, regardless of how the user entered it inside your application:

Dear {{ my_variable.capitalize() }}:

    I am writing to tell you...

Use conditional text​

One of the most common uses of Jinja tags inside a docx template is to insert conditional text. There are two types of conditionals: in-line, and paragraph/bullet level conditionals.

In-line conditional statements​

Jinja in-line conditionals are started with a curly brace and a % symbol, like {% if condition %} and closed with {% endif %}. You can optionally include both {% elif %} and {% else %} tags.

You are {% if person.age_in_years() < 13 %} a child {% elif person.age_in_years() < 20 %} a teenager {% else %} an adult. {% endif %}

Paragraph-level conditional statements​

Sometimes you want to hide an entire paragraph if a certain condition is met. One time you may want to use this when several optional items are shown on a list. In this case, you use a slight variation: {%p if... %}.

* Apple
* {%p if likes_bananas %}
* Bananas
* {%p endif %}

If you leave out the p, you would have an empty line after Apple. Using p tells Docassemble to remove that line from the document.

Make sure you use the {%p endif %} form to close the statement. Otherwise, Docassemble will raise an error that there is an unmatched if statement.

Use control structures​

Control structures use the same syntax as conditional statements, surrounded by {% %} or {%p %}. You can use the same control structures (for and while) in Jinja that you can use in Python and wherever you can use Mako statements.

{%p for fruit in fruits %}
* {{ fruit }}
{%p endfor %}

Further reading​