Template should not evaluate outside the templating expression marks (eg `{{ }}`) #723

dipsywong98 · 2025-03-11T06:06:45Z

Current Behavior

With my previous experience working with templating stuff, the evaluation of values should only happen between {{ }}, and outside the {{ }} should remain untouched/unchanged, however it is not the case in configu.

For example I have a file back-tick.txt, its content is just

Run configu eval | configu export --template examples/back-tick.txt it will give

configu eval | configu export --template examples/back-tick.txt 
│
◇  Configs evaluated successfully
│
■  template expression evaluation failed: Error: Failed to evaluate expression "````"
│  "" is not a function

which it is expected to just give

Currently we need to prepend \ before to give the expected content, which is counter intuitive.

Another example is \n

For example we have a line-break.json

{
  "title": "Hello",
  "paragraph": "{{$.configs.MESSAGE.value}}\nIt is a nice day"
}

configu eval | configu export --template examples/line-break.json it gives the following, which breaks the json syntax

{
  "title": "Hello",
  "paragraph": "Hi there!
It is a nice day"
}

which I expect it gives the following instead, that does not evaluate the line break character

{
  "title": "Hello",
  "paragraph": "Hi there!\nIt is a nice day"
}

Now I need to add extra \ to avoid \n being evaluated, which is not supposed to be a templating engine's behavior

{
  "title": "Hello",
  "paragraph": "{{$.configs.MESSAGE.value}}\\nIt is a nice day"
}

Expected Behavior

it is in above

To Reproduce

No response

Context

No response

The text was updated successfully, but these errors were encountered:

rannn505 · 2025-03-16T14:14:38Z

Hi @dipsywong98, you're correct—before v1, this was indeed the behavior. For v1, we considered this extensively and made deliberate choices to maintain backward compatibility with the original {{ }} syntax while introducing a more powerful, JavaScript-based templating language leveraging backticks and ${} literals.

Additionally, we're planning to support other familiar templating syntax styles by introducing multiple configurable delimiters. In the future, you might be able to opt-in or out of specific templating styles via .configu configuration settings, allowing you to select the approach that best fits your needs. However, the default approach is likely to remain JavaScript-based template literals (with backticks and ${}).

In the meantime, escaping literals remains necessary, but this direction ensures maximum flexibility and backward compatibility for diverse use cases.

see #718 (comment) for an example of template

dipsywong98 added the bug Something isn't working label Mar 11, 2025

github-actions bot added triage The issue is new and needs to be triaged by a maintainer community labels Mar 11, 2025

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Template should not evaluate outside the templating expression marks (eg `{{ }}`) #723

Template should not evaluate outside the templating expression marks (eg `{{ }}`) #723

Template should not evaluate outside the templating expression marks (eg {{ }}) #723

Template should not evaluate outside the templating expression marks (eg {{ }}) #723

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Current Behavior

Expected Behavior

To Reproduce

Context

Template should not evaluate outside the templating expression marks (eg `{{ }}`) #723

Template should not evaluate outside the templating expression marks (eg `{{ }}`) #723