Jinja2 template variable if None Object set a default value

Question

How to make a variable in jijna2 default to \"\" if object is None instead of doing something like this?

      {% if p %}   
        {{ p.User[\'first_name\'         


        

Answer 1

Following this doc you can do this that way:

{{ p.User['first_name']|default('NONE') }}

Answer 2

To avoid throw a exception while "p" or "p.User" is None, you can use:

{{ (p and p.User and p.User['first_name']) or "default_value" }}

Answer 3

As of Ansible 2.8, you can just use:

{{ p.User['first_name'] }}

See https://docs.ansible.com/ansible/latest/porting_guides/porting_guide_2.8.html#jinja-undefined-values

Answer 4

According to docs you can just do:

{{ p|default('', true) }}

Cause None casts to False in boolean context.

---

Update: As lindes mentioned, it works only for simple data types.

Answer 5

As another solution (kind of similar to some previous ones):

{{ ( p is defined and p.User is defined and p.User['first_name'] ) |default("NONE", True) }}

Note the last variable (p.User['first_name']) does not have the if defined test after it.

Answer 6

Use the none builtin function (http://jinja.pocoo.org/docs/templates/#none):

{% if p is not none %}   
    {{ p.User['first_name'] }}
{% else %}
    NONE
{%endif %}

or

{{ p.User['first_name'] if p != None else 'NONE' }}

or if you need an empty string:

{{ p.User['first_name'] if p != None }}