Jinja2 2.9.4 - {% set %} and {% include %} don't work in the same template.

[andymcc]

Expected Behavior

When a template contains:

{% set myvar = "foo" %}
{{ myvar }}
{% include "include.j2" %}

And the include.j2 template contains anything, for example:

bar

The original template should render:

foo
bar

Actual Behavior

In 2.8 this works normally.

In 2.9.3 & 2.9.4 the template doesn't render at all and drops an error:

KeyError: 'undefined variable: 0'

However, it will render with the {% set %} line templated when no {% include %} line exists, e.g.:

{% set myvar = "foo" %}
{{ myvar }}

Or with the {% include %} line without the {% set %} line, e.g.:

{% include "include.j2" %}

Template Code

root@jinja2fix# cat templates/setincl.j2
{% set myvar = "foo" %}
{{ myvar }}
{% include "include.j2" %}

root@jinja2fix# cat templates/include.j2
bar

Actual Run

I'm using Ansible 2.2.0 (I'll file a bug with Ansible too as I know this may not be considered a Jinja2 bug) - it's easily repeatable with the ad-hoc ansible command though:

root@jinja2fix:/opt/test_jinja# ansible localhost -m template -a "src=setincl.j2 dest=/tmp/test.file"

localhost | FAILED! => {
    "changed": false,
    "failed": true,
    "msg": "KeyError: 'undefined variable: 0'"
}

Here is a more "complete" run to show the failure and success (in 2.8). Additionally, it shows that it will render properly with either just the {% set %} line, or just the {% include %} line - but not both.

https://gist.github.com/andymcc/2ddf98b50fa07e3f8b8648a440499fb8

I've added to a bug in Ansible, that already exists and seems related: ansible/ansible#20063

Your Environment

• Python version: 2.7.12
• Jinja version: 2.9.3 & 2.9.4 (tested on both)

[mitsuhiko]

I cannot reproduce this at all in Jinja2. Added this regression test in 3e9937c but it passes.

[mitsuhiko]

There must be more to this story. I'm going to close this bug however I will monitor the mentioned issue over here: ansible/ansible#20063

[ghost]

I have the same bug.

<div id="owl{{ carousel_count }}" class="owl-carousel owl-theme">
    {% set owl_count=0 %}
    {% set owl_all = channels | length %}
    {% for owl_channel in channels %}

        {% set owl_count=owl_count+1 %}

        {% if owl_all<14 or owl_count % 2 != 0 %}
            <div class="item">
        {% endif %}

    <div class="ps-bl">
        <img src="{{ owl_channel.image }}" style="cursor: pointer;"
             onclick="goChannel('{{ owl_channel.url }}')"/>
        <div class="tit-chanel" style="cursor: pointer;">{{ owl_channel.name }}</div>
        <div class="flg j1 ato-flag"><img src="{{ owl_channel.flag }}" alt=""></div>
        <a class="love" href="#" data-id="{{ owl_channel.id }}"></a>
    </div>

    {% if owl_all < 14 or owl_count %2 == 0 or owl_count == owl_all %}
        </div>
        <!-- .item-->
    {% endif %}

    {% endfor %}

</div>

The problem with owl_count. It always equals 1.
With Jinja2 2.8 it works fine.

[ThiefMaster]

This looks a lot like something that could be done much cleaner with the batch filter. Also, check out the various attributes exposed on the loop object.

[mitsuhiko]

Variables cannot be set in loops and that is intentional. It was never documented that you can override variables from higher scopes and that was considered a bug. See also #641

[ThiefMaster]

Maybe it'd be worth raising an exception when trying to do this in a way that worked in 2.8 but breaks in 2.9 to make it very clear that something is going wrong (except for weird behavior one might not notice immediately)?