How to test for an item in a list?

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1

My apologies if there’s an obvious solution to this, but I’ve been unable to find it.

I have a list variable defined with some values, eg:

mylist:

  • aaa
  • bbb
  • ddd

I need to execute a task conditionally based on whether the value of a variable is a member of that list. In other words, if myvar is set to “aaa”, “bbb”, or “ddd” I want to execute my task, but if it’s set to anything else the task should be skipped.

When I ran into this, I expected to find a Jinja filter called something like “contains” or “includes” such that I could do this:

tasks:

  • debug: msg=“Found the value in mylist”
    when: mylist|contains(myvariable)

But I haven’t been able to find any filters that do this. I did come up with this alternative solution:

tasks:

  • debug: msg=“Found the value in mylist”
    when: mylist|intersect([myvariable])|count > 0

But that feels really hacky and is hard to read at a glance. Is there a Jinja filter I’m overlooking, or some better way to do this?

Thanks!

-dave

2

Regular Python should work in this case:

when: myvariable in mylist

You need to quote the whole condition if it starts with a literal string, though:

when: “‘literal string’ in mylist”

3

I knew I was missing something obvious. I totally blanked that you can use straight Python in when. Duh. Thanks!

4

Technically when statements use jinja2 template syntax, but since that is pretty much straight python in most cases there is a lot of similarity.