Make sure a data value exists

support
1

I’m using .Site.Data.file.value to read some key data into my homepage template. This works fine but I want this usage to fail with an error on build if the value doesn’t exist. I’ve looked through the build flags and available template functions but I can’t find anything that “asserts” or “requires” a value to be a non-empty or non-nil value.

Does this exist already, or should I try to create a partial template which spits out an error?

2

Try this:

{{ with .Site.Data.file.value }}
  {{ $value := . }}
{{ else }}
  {{ errorf "WARN ERROR" }}
{{ end }}
3

That’s a clever way to use the with operator, but I’d like something even shorter since I tend to want to know when a value is missing before I deploy rather than maybe (or not) discovering it later.

I see that Go templates have an option missingkey=error which would solve this globally if it was set. It would be nice if this option could be set from the command line.

I could maybe create a preprocessor or something similar that would inject your code whenever an assert function was found?

4

errorf will stop the hugo build and throw error.

Any ERROR will also cause the build to fail (the hugo command will exit -1 ).

5

Yep, I made this partial template and put it in layouts/partials/require.html

{{ if . }}
  {{ . }}
{{ else }}
  {{ errorf "REQUIRE FAILED" }}
{{ end }}

Use it like this:

{{ partial "require" 123 }}
6

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