support for legacy content collections removed

[sarah11918]

This adds "Removed: content collections" to the v6 upgrade guide

Direct deploy preview: https://deploy-preview-12376--astro-docs-2.netlify.app/en/guides/upgrade-to/v6/#removed-legacy-content-collections

Implementation PR #14407

This PR should include

• Upgrade guide content for removal
• Remove legacy flag docs
• placeholder error messages so that links will work (both to them, and allow us to check links in them, if necessary)
  • the content here doesn't have to be 100% accurate -- it will be overwritten with the JSDoc eventually
  • I did not (yet?) bother to add these to the error index page as that will also be autogenerated and isn't needed for resolving or checking links

Notes:

• there should not be any new astro:content reference updated needed: v5 already only documents the newest API
• any guide/reference changes will be handled along with Live Collections becoming stabilized (which will probably affect how we describe collections in general, and will bring larger docs needs around collections and API reference)

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en/reference/errors/content-collection-missing-loader.mdx	Localization added, will be marked as complete.
en/reference/errors/legacy-content-config-error.mdx	Localization added, will be marked as complete.
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[ascorbic]

I don't think we're uisng the "content layer" terminology externally, are we?

[sarah11918]

We do have it scattered around the content collections page, but we can choose to remove that now that a) there's absolutely no need to distinguish between legacy anymore and b) we will have live collections, so probably need some repositioning anyway.

It might still be helpful here and there in the upgrade guide, when the phrase was in use for v5? But I think we can for sure now remove it from our regular documentation for v6.

[ascorbic]

Suggested change

	**Astro v6.0 removes this previously deprecated Content Collections API support entirely, including the `legacy.collections` flag.** All content collections must now use the Content Layer API introduced in Astro v5.0 that powers all content collections. No backwards compatibility support is available.
	**Astro v6.0 removes this previously deprecated legacy content collections API support entirely, including the `legacy.collections` flag.** All content collections must now use the new API introduced in Astro v5.0 that powers all content collections. No backwards compatibility support is available.

[ascorbic]

We should add the error messages in here too

[ArmandPhilippot]

Yes, this could be helpful, or at least the error code so someone can easily identify the details to expand.

[sarah11918]

Great idea! Would the implementation PR be a comprehensive list of all the ones they might encounter?

I'm seeing:

• 'LegacyContentConfigError'
• 'ContentCollectionMissingLoader'
• 'ContentCollectionInvalidType'

What we did for v5 was mock up the new errors / config in the v5 branch (duplicating what would be generated from the JSDoc), so we should probabably manually recreate those errors in this PR, too. If they end up not being identical, then a ci PR will be generated to align them.

Just copied the entire jsdoc from entries here for now

• @docs
• @message
• Example error message:
  
• Found legacy content config file in "src/content/config.ts". Please move this file to "src/content.config.ts" and ensure each collection has a loader defined.
  
• @description
• A legacy content config file was found. Move the file to src/content.config.ts and update any collection definitions if needed.
• See the Astro 6 migration guide for more information.
  */

export const LegacyContentConfigError = {
name: 'LegacyContentConfigError',
title: 'Legacy content config file found.',
message: (filename: string) =>
Found legacy content config file in "${filename}". Please move this file to "src/content.config.${filename.split('.').at(-1)}" and ensure each collection has a loader defined.,
hint: 'See https://docs.astro.build/en/guides/upgrade-to/v6/#removed-legacy-content-collections for more information on updating collections.',
} satisfies ErrorData;

/**

• @docs
• @message
• Example error message:
  
• Collections must have a loader defined. Check your collection definitions in your content config file.
  
• @description
• A content collection is missing a loader definition. Make sure that each collection in your content config file has a loader.
• See the Content collections documentation for more information.
  */

export const ContentCollectionMissingLoader = {
name: 'ContentCollectionMissingLoader',
title: 'Content collection is missing a loader definition.',
message: (file = 'your content config file') =>
Collections must have a \loader` defined. Check your collection definitions in ${file}.`,
hint: 'See https://docs.astro.build/en/guides/content-collections/ for more information on content loaders and https://docs.astro.build/en/guides/upgrade-to/v6/#removed-legacy-content-collections for more information on migrating from legacy collections.',
} satisfies ErrorData;

/**

• @docs
• @message
• Example error message:
  
• Invalid collection type "data". Remove the type from your collection definition in your content config file.
• @description
• Content collections should no longer have a type field. Remove this field from your content config file.
• See the Astro 6 migration guide for more information.
  */

export const ContentCollectionInvalidType = {
name: 'ContentCollectionInvalidType',
title: 'Content collection has an invalid type field.',
message: (type: string, file = 'your content config file') =>
Invalid collection type "${type}". Remove the type from your collection definition in ${file}.,
hint: 'See https://docs.astro.build/en/guides/upgrade-to/v6/#removed-legacy-content-collections for more information on migrating from legacy collections.',
} satisfies ErrorData;

[ascorbic]

There are also some places where we just log a warning rather than throwing an error:

https://github.com/withastro/astro/pull/14407/files#diff-04e44d3cde1db4d52d43a7732043f5239e1c49479b993e3dda7486399a5a51fbR214-R223

[ascorbic]

I could add a more searchable name there too.

[ArmandPhilippot]

A small nit, otherwise I think this format looks great and makes sense!

[sarah11918]

Suggested change

	**Astro v6.0 removes this previously deprecated Content Collections API support entirely, including the `legacy.collections` flag.** All content collections must now use the Content Layer API introduced in Astro v5.0 that powers all content collections. No backwards compatibility support is available.
	**Astro v6.0 removes this previously deprecated Content Collections API support entirely, including the `legacy.collections` flag.** All content collections must now use [the Content Layer API introduced in Astro v5.0](https://astro.build/blog/content-layer-deep-dive/) that powers all content collections. No backwards compatibility support is available.

For example, we could do this here, then use all the rest of your suggestions for just legacy/new. This link is probably more important than the 2.0 one, and we could even remove the other link in favour of just this one.

[sarah11918]

Suggested change

	If you have content collections errors after upgrading to v6, use the following list to help you identify and upgrade any legacy features that may exist in your code.
	If you have [content collections errors](/en/reference/error-reference/#content-collection-errors) after upgrading to v6, use the following list to help you identify and upgrade any legacy features that may exist in your code.

The link exists, but I haven't bothered to put these individual errors on the index page. I don't know whether we need to explicitly include the 3 legacy errors here, or just point them to the content collections general set of errors.