How do I determine the last (final) layout in the layout chain when developing custom extension for template engine? #3157

monochromer · 2024-01-09T17:16:39Z

monochromer
Jan 9, 2024

I am trying to create an integration of Eleventy and Preact as a template engine

Eleventy passes the rendered template to the parent layouts inside the content property as raw HTML strings.

For example, for the Nunjucks template engine, it looks like this

// index.md

---
layout: article
title: Some title text
---

some text

// article.njk

---
layout: root
---
<article>
  {{ content | safe }}
</article>

// root.njk

<!DOCTYPE html>
<html>
  <head>
    <title>{{ title }}</title>
  </head>
  <body>
    {{ content | safe }}
  </body>
</html>

But I want to pass objects, not strings. I don't know yet if these will be virtual nodes or functional components.

For Preact, it will look like this:

// index.md (I will replace default md render to custom method, which return components instead of html string)

---
layout: article
title: Some title text
---

some text

// article.jsx

---
export const data = {
  layout: 'root'
}

export default function ArticleLayout(props) {
  return (
    <article>
      {{ props.children }}
    </article>
  )
}

// root.jsx

export default function RootLayout() {
  const context = useEleventyContext()

  return (
    <html>
      <head>
        <title>{{ context.data.title }}</title>
      </head>
      <body>
        {{ props.children }}
      </body>
    </html>
  )
}

But in the end, you still need to render the result to a string, like this:

'<!DOCTYPE html>' + renderToString(Component)

How do I determine that the layout is the last one and I need to render everything in a string?

I had the idea to write a special property in the layout:

// root.jsx

export default function RootLayout() {}

RootLayout.isFinalLayout = true

Then, in the extension itself, determine the type of render based on this property (pseudocode):

eleventyConfig.addExtension('jsx', {
  read: false,
  outputFileExtension: 'html',
  async compile(inputContent, inputPath) {
    const Component = require(inputPath).default
    return async (data) => {
      if (component.isFinalLayout) {
        return '<!DOCTYPE html>' + renderToString(<Component data={data} />)
      } else {
        return Component
      }
    }
  }
})

But I want it to be transparent for the extension user and he does not need to manually set such flags.

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How do I determine the last (final) layout in the layout chain when developing custom extension for template engine? #3157

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How do I determine the last (final) layout in the layout chain when developing custom extension for template engine? #3157

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monochromer Jan 9, 2024

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monochromer
Jan 9, 2024