Concatenation not working in if expression (inline if-else) with Jinja2 on Ansible

Question

So, I'm trying to create a sort of multiple alternative variable thing in Jinja and since this

{{ var1.x | var2.x | default('', true) }}

does not work, since var2 is not a filter...

I am using inline if expressions like so

{{ var1.x if var1.x is defined else var2.x | default('', true) }}

to achieve that. But now I want to concatenate a string to both vars but not the default value, so I tried to do this

{{ var1.x ~ '-' if var1.x is defined else var2.x ~ '-' | default('', true) }}

but the concatenation in the else is not allowed for some reason, as Ansible outputs an error from it! -vvv gives no extra info.

An exception occurred during task execution. To see the full traceback, use -vvv. The error was: ansible.errors.AnsibleUndefinedVariable: 'dict object' has no attribute 'x'
fatal: [default]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'dict object' has no attribute 'x'"}

But if I do this

{{ var1.x ~ '-' if var1.x is defined else var2.x | default('', true) }}

it works... Why? And how can I achieve what I'm trying to do?

Answer 1

As it turns out, the problem is very easy to fix...

I did not think that you could chain inline if expressions in Jinja like you can in almost all programming languages...

My problem is fixed by:

{{ var1.x ~ '-' if var1.x is defined else var2.x ~ '-' if var2.x is defined | default('', true) }}

Thanks to @Rivers who made me look elsewhere for bugs, which actually made me realize that the error message was correct and I was just being foolish