How to compare variables for equality?

[anakadote]

In v2 I could filter form submissions by their data, but that's no longer working:

{{ form:submissions in="payment" transaction_id:is="{session:payment_transaction_id}" limit="1" }}

In v3 the above outputs all the submissions. So now I'm trying to use an if condition to only output the targeted submission.
I've tried every possible way I can think of to compare the session variable against the submission variable for equality, to no avail:

{{ form:submissions in="payment" }}

    // Some of the variations I've tried...
    {{ if {session:payment_transaction_id} == transaction_id }}
    {{ if {session:payment_transaction_id} == {transaction_id} }}
    {{ if session:payment_transaction_id == transaction_id }}
    {{ if session:payment_transaction_id == {transaction_id} }}
    {{ if {session:payment_transaction_id} is transaction_id }}
    {{ if {session:payment_transaction_id} equals transaction_id }}

None of the above resolve to true, and some throw exceptions. Any help is appreciated!

And here's an example form submission yaml file:

transaction_id: test_6201982ddadd0
first_name: Test
last_name: Person
company: 'Obrien Guy Plc'
email: test@mailinator.com
phone: '(179) 449-3570'
comments: 'Est quia omnis lore'
invoice: 'Minus labore dolores'
amount: '12.33'
zip: '84428'

[jackmcdade]

You almost had it! Let's go over the rules so you can understand what does and doesn't work.

session is Tag, which means it needs to be wrapped in single braces: {session:payment_transaction_id}. On the other hand, transaction_id is a var, so it doesn't. is and equals aren't a thing, which leads you to...

{{ if {session:payment_transaction_id} == transaction_id }}

[anakadote]

Thanks, @jackmcdade , but that was the first one in my list of attempts above. I guess that means there's something else going on, hm...

[jackmcdade]

I feel really dumb – missed it entirely. 😅

What does {{ session:payment_transaction_id }} return inside the {{ form:submissions }} tag?

[anakadote]

It returns the correct value (test_6201982ddadd0 in this case). I just setup a bare minimum test:

{{ session:set payment_transaction_id="test_6201982ddadd0" }}

<div class="p-5">
{{ form:submissions in="payment" }}

    Testing: {{ session:payment_transaction_id }} == {{ transaction_id }}<br>

    {{ if {session:payment_transaction_id} == transaction_id }}

        YES

    {{ else }}

        NO

    {{ /if }}

{{ /form:submissions }}
</div>

Which outputs this: