[gatsby-plugin-mdx]: Combining/concatenation/transclusion of MDX files

[nikhilxb]

Summary

I'm trying to break up a large Markdown (.mdx) file into multiple smaller ones, where each one has footnotes:

In parent.mdx:

import Child1 from "./child1.mdx";
import Child2 from "./child2.mdx";
<Child1 />
<Child2 />

In child1.mdx:

This sentence has a footnote [^foo].
[^foo]: Footnote 1.

In child2.mdx:

This sentence has a footnote [^bar].
[^bar]: Footnote 2.

Since each child MDX is compiled then included in parent MDX, this results in 2 separate footnotes sections rather that 1 unified footnote section, as desired. What I want is true transclusion of the raw text (something like #include), ideally a solution that supports recursion (i.e. child can also #include a snippet).

What I've tried

• Using https://github.com/hashicorp/remark-plugins/blob/master/plugins/include-markdown/index.js, but it uses remark to parse regular MD files and doesn't seem to work for MDX.
• Writing a custom remark plugin, but I'm not sure how to recursively generate the AST using the functions provided by gatsby-plugin-mdx.
• Manually overwriting .mdx File's node.internal.content in onCreateNode to concatenate the raw text, but gatsby-plugin-mdx doesn't seem to be affected.
• Writing a preprocessing plugin as suggested in feat(gatsby-transformer-remark): Add a filter to preprocess raw content #15868, but that doesn't work for gatsby-plugin-mdx as noted in [gatsby-plugin-mdx] Remark plugins using mutateSource seems to be ignored #23409

Any ideas?

Motivation

Particularly for large projects, it's useful to break posts into more manageable chunks.

[FrancoisDF]

I'm also interested by this feature. I have also tried different solution without success. I know that we can import markdown as a component, but my main concern is that those components will then be part of the bundle. If preprocessing was possible, we could import the markdown content inside a markdown without extra layer of javascript bundling. This will dramatically reduce the bundle size and improve prefromances