# Custom Jinja tests? **URL:** \ **Category:** Ansible Project\ **Created:** [May 25, 2014, 9:28pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328 "2014-05-25T21:28:19Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Joost\_Cassee](https://avatars.discourse-cdn.com/v4/letter/j/898d66/32.png) [@Joost\_Cassee](https://forum.ansible.com/u/Joost_Cassee)\ **Post date:** [May 25, 2014, 9:28pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/1 "2014-05-25T21:28:19Z")
Hi, Custom template filters are a great way to take the programming out of my playbooks. Sometimes I would like to have a Jinja test, though. For example, I have a filter ‘is\_in\_zone(domain, zone)’ to see if a domain ends with a certain tail. For example, ‘[test.example.com](http://test.example.com)’ is in zone ‘[example.com](http://example.com)’ (and in ‘com’). {{ domain | is\_in\_zone(zone) }} would look nicer as {{ domain is in\_zone(zone) }}, and having it as a test would also make it possible to use it in ‘select’ filters. Is it possible to create custom Jinja tests? If not, where in the code should I look if I want to take a stab at adding that feature? Regards, Joost ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [May 25, 2014, 9:32pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/2 "2014-05-25T21:32:36Z")
What you are describing is a Jinja2 filter. Read about filter plugins here and search the source tree for “core.py” for plenty of examples. [http://docs.ansible.com/developing\_plugins.html](http://docs.ansible.com/developing_plugins.html) ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [May 25, 2014, 9:33pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/3 "2014-05-25T21:33:16Z")
Also this is also a topic for ansible-devel 🙂 It’s international join-ansible-devel advocacy day! [https://groups.google.com/forum/#!forum/ansible-devel](https://groups.google.com/forum/#!forum/ansible-devel) ---
**Author:** ![sivel](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/sivel/32/1198_2.png) [@sivel](https://forum.ansible.com/u/sivel)\ **Post date:** [May 25, 2014, 9:50pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/4 "2014-05-25T21:50:34Z")
Additionally you could achieve this using the regex “|search” filter or even the python string method .endswith() ---
**Author:** ![Joost\_Cassee](https://avatars.discourse-cdn.com/v4/letter/j/898d66/32.png) [@Joost\_Cassee](https://forum.ansible.com/u/Joost_Cassee)\ **Post date:** [May 26, 2014, 9:06am UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/5 "2014-05-26T09:06:00Z")
Moving to ansible-devel. 🙂 ---
**Author:** ![Joost\_Cassee](https://avatars.discourse-cdn.com/v4/letter/j/898d66/32.png) [@Joost\_Cassee](https://forum.ansible.com/u/Joost_Cassee)\ **Post date:** [May 26, 2014, 9:25am UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/6 "2014-05-26T09:25:04Z")
[Moved from ansible-project.] > Additionally you could achieve this using the regex "|search" filter or even > the python string method .endswith() Thanks for that, indeed. That fixes my use-case. Do you think tests are never needed? > What you are describing is a Jinja2 filter. Not really. Filters cannot be used in 'is' expressions or 'select' filters. (I do realize that the distinction is small, and many times a filter will do very nicely.) Let me demonstrate with the 'search' filter. The first of the tasks in this playbook succeeds while the second one fails: - hosts: all   gather\_facts: no   tasks:   - debug: msg=filter     when: "'foo.example.com' | search('\\.example\\.com$')"   - debug: msg=test     when: "'foo.example.com' is search('\\.example\\.com$')" Granted, Jinja tests are basically syntactic sugar for filters, but they are nice sometimes. Is there interest in supporting custom tests? Regards, Joost ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [May 27, 2014, 8:08pm UTC](https://forum.ansible.com/t/custom-jinja-tests/15328/7 "2014-05-27T20:08:27Z")
Ok, so they are filters. You’d still write a filter plugin, you would just either return the value directly passed in or raise an exception. Which is I’m guessing exactly what the filters do.