feat: add binding for external vars

[maximepvrt]

External variables binding for nuxt/content#2053

I've implemented a feature that allows for external variable binding within the Nuxt (Content) MDC project. This enhancement enables seamless integration of external variables into the project, thereby enhancing its functionality and flexibility.

To provide a bit of context, I had initially introduced this binding capability to my personal fork of the project before the extraction of MDC from Nuxt Content. maximepvrt/nuxt-content@57d5845

As of now, I acknowledge that I haven't yet included tests for this feature. I am aware of the importance of testing in ensuring the stability and reliability of the project. However, I've encountered some challenges in devising the appropriate testing strategy, particularly given the specific nature of the binding functionality. Additionally, I've been unable to locate existing tests for the binding aspect within the MDC project.

I remain enthusiastic about contributing to the Nuxt Content MDC project and ensuring its continued growth and improvement.

<template>
  <MDC v-slot="{ data, body }" :value="md">
        <MDCRenderer
          :body="body"
          :data="data"
          :prose="false"
          :vars="mdcVars"
        />
  </MDC>
</template>

<script setup lang="ts">

const mdcVars = ref({ name: 'Maxime'});

const md = `
::alert
Hello {{ $vars.name }}
::
`
</script>

[farnabaz]

Hey @maximepvrt,
Is there any specific reason for not using data prop to pass external variables to the renderer?

[maximepvrt]

Hey @farnabaz,

Thank you for your feedback. I created a new MR in nuxt/content#2296 used the data props to pass external variables to the renderer.

With this current implementation, external variables are accessible through the $doc object (e.g., $doc.firstname) within the ContentRendererMarkdown component. This behavior may appear unusual.

If you have any suggestions regarding this approach or if you believe there's a more elegant solution, please feel free to share your thoughts.

Best,

[farnabaz]

Introducing new user-provided source of data for runtime is a tricky thing to support in the module's roadmap.

I know that using $doc may sounds not good but for now it is the only options and note that it might face changes in next major release.

I'll keep this feature pending for now.

[maximepvrt]

@farnabaz did you see my MR nuxt/content#2296