Use pkl to validate existing config files #172

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adam · 2025-12-30T01:21:44+01:00

adam commented

2025-12-30 01:21:44 +01:00

Originally created by @derphilipp on GitHub (Jun 25, 2024).

Is it possible to achive:

Write a pkl template to validate types
Write a Go(lang) program that reads an already existing json file and validate it with the help of the pkl template file

This way golang programs could harness the power of pkl without modifying the user expirience / config files of existing tools

Originally created by @derphilipp on GitHub (Jun 25, 2024). Is it possible to achive: - Write a pkl template to validate types - Write a Go(lang) program that reads an already existing json file and validate it with the help of the pkl template file This way golang programs could harness the power of pkl without modifying the user expirience / config files of existing tools

adam closed this issue

2025-12-30 01:21:44 +01:00

adam commented

2025-12-30 01:21:45 +01:00

@holzensp commented on GitHub (Jun 25, 2024):

[aside: I'd prefer questions like this under Discussions]

Yes. You don't even need to write a Go program for the validation. That said, I think our editing experience is better than most JSON experiences. I guess "existing tools" might be a deal-breaker. Anyway, yes, you can always add the following to any template;

import "pkl:json"
import "package://pkg.pkl-lang.org/pkl-pantry/pkl.experimental.deepToTyped@1.0.2#/deepToTyped.pkl"

output {
  value = deepToTyped.apply(module.getClass(), new json.Parser {}.parse(read(read("prop:JsonPath"))))
}

Now, if you invoke Pkl with a value for external property JsonPath to point to your .json file, you can consume output.value as an instance of the module it's defined in.

@holzensp commented on GitHub (Jun 25, 2024): [aside: I'd prefer questions like this under Discussions] Yes. You don't even need to write a Go program for the validation. That said, I think our editing experience is better than most JSON experiences. I guess "existing tools" might be a deal-breaker. Anyway, yes, you can always add the following to any template; ``` import "pkl:json" import "package://pkg.pkl-lang.org/pkl-pantry/pkl.experimental.deepToTyped@1.0.2#/deepToTyped.pkl" output { value = deepToTyped.apply(module.getClass(), new json.Parser {}.parse(read(read("prop:JsonPath")))) } ``` Now, if you invoke Pkl with a value for external property `JsonPath` to point to your `.json` file, you can consume `output.value` as an instance of the module it's defined in.

adam commented

2025-12-30 01:21:46 +01:00

@derphilipp commented on GitHub (Jun 25, 2024):

Thank you very much and you are absolutely right, this should be under 'Discussion'!

@derphilipp commented on GitHub (Jun 25, 2024): Thank you very much and you are absolutely right, this should be under 'Discussion'!

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Reference: starred/pkl#172