Empty Markdown frontmatter at build time

[PaulFarault]

What version of astro are you using?

1.0.6

Are you using an SSR adapter? If so, which one?

None

What package manager are you using?

npm

What operating system are you using?

Linux

Describe the Bug

When creating custom Markdown plugins (as in the doc):

• Frontmatters are empty at build time.
• It seems that Markdown files are processed twice at build time.

The output is correct at the end but the lack of frontmatter makes development harder.

Link to Minimal Reproducible Example

https://stackblitz.com/edit/withastro-astro-vgrdek?file=content%2Farticle1.md,content%2Farticle2.md,astro.config.ts,src%2Fplugins%2FremarkGetTitle.ts,src%2Fpages%2Findex.astro

Participation

• I am willing to submit a pull request for this issue.

[bholmesdev]

Thanks for reporting @PaulFarault! So to be clear, the issue is "I expect my markdown frontmatter to be in file.data.astro.frontmatter, but it's an empty object instead?" Because that's a fair critique! Currently, we merge plugin frontmatter with your file's frontmatter at the end, without passing the file frontmatter to your plugins. I've been considering a change there too.

I'm also unable to see the "MD files are processed twice" issue when building in your stackblitz example. I see this output:

Before plugin: {}
After plugin: { title: 'Default title' }
Before plugin: {}
After plugin: { title: 'Default title' }

Since there are 2 markdown files, this should mean the files were processed only once? Lmk if I'm missing something here.

[PaulFarault]

Hi Ben! Thx for your answer!

I expect my markdown frontmatter to be in file.data.astro.frontmatter, but it's an empty object instead?

It's exactly that. Thanks for explaining me how it works. Would be nice to be able to have the frontmatter directly, for developping ease and even testing purposes!

---

Since there are 2 markdown files, this should mean the files were processed only once?

I got the same output as you but twice, which I interpreted as "MD files are processed twice". I may have misinterpreted tho.

Before plugin: {}
After plugin: { title: 'Default title' }
Before plugin: {}
After plugin: { title: 'Default title' }
Before plugin: {}
After plugin: { title: 'Default title' }
Before plugin: {}
After plugin: { title: 'Default title' }

[azan-n]

• Frontmatters are empty at build time.

Was planning to make a 'Fake-CMS' remark plugin that would check the frontmatter for the properties I wanted to be present in every document. However, I recognized that this would be a bit of a hacky workaround. I'm glad I ran through Github issues because I found this beautifully detailed RFC:

https://github.com/withastro/rfcs/blob/content-schemas/proposals/0027-content-schemas.md

Kudos to @bholmesdev and the team, I am sorry if this goes off-topic, but I would be glad to contribute in whatever way.