Clarification: nil vs empty string about sprig HOT 7 CLOSED

Found a solution {{ kindIs "invalid" $value }}

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Wow. That issue actually helped me nail down an issue I was seeing in a local PVC! Ha!

Okay, so an {{ if $value }} will check for both "" and nil, considering either one to be an "empty value". There is also the empty function, which essentially behaves the same way.

It might be nice to be able to test whether something is nil and possibly empty ({{ if isNil $foo }}). I don't think we have a way of checking that. Maybe eq $foo nil would work... I've never tried.

Does that answer your question, or am I misunderstanding.

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@scottrigby @technosophos Here's an example of the previous comment... https://play.golang.org/p/9yJW5iGT4qa

When I looked at this in the past I'd not thought of this. Thanks @jkroepke

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OK, I found the relevant helm issue: helm/helm#2600

But just checking here, is there really no way for sprig to differentiate the difference between nil and "" (empty string) in a template? If not, would that be a desirable PR?

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@technosophos If something is a string, isn't the initialized value on a struct "" instead of nil? How would you get the nil state without the template engine complaining about the missing field?

I imagine I'm missing something which is why I ask.

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Love it 😄

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Found a solution {{ kindIs "invalid" $value }}

@jkroepke While this solution might work, I imagine there are other cases where the "kind" of something might be "invalid" without it being nil.

I think better option is to use a direct equality check against nil:

{{ eq $value nil }}

PS: the reason that the kind of nil equals "invalid" is actually because nil does not have a type in Go, because it is a "predeclared identifier".

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