48 lines
1.8 KiB
Markdown
48 lines
1.8 KiB
Markdown
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---
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'astro': major
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'@astrojs/markdown-remark': major
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'@astrojs/mdx': minor
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---
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Give remark and rehype plugins access to user frontmatter via frontmatter injection. This means `data.astro.frontmatter` is now the _complete_ Markdown or MDX document's frontmatter, rather than an empty object.
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This allows plugin authors to modify existing frontmatter, or compute new properties based on other properties. For example, say you want to compute a full image URL based on an `imageSrc` slug in your document frontmatter:
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```ts
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export function remarkInjectSocialImagePlugin() {
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return function (tree, file) {
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const { frontmatter } = file.data.astro;
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frontmatter.socialImageSrc = new URL(
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frontmatter.imageSrc,
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'https://my-blog.com/',
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).pathname;
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}
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}
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```
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#### Content Collections - new `remarkPluginFrontmatter` property
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We have changed _inject_ frontmatter to _modify_ frontmatter in our docs to improve discoverability. This is based on support forum feedback, where "injection" is rarely the term used.
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To reflect this, the `injectedFrontmatter` property has been renamed to `remarkPluginFrontmatter`. This should clarify this plugin is still separate from the `data` export Content Collections expose today.
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#### Migration instructions
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Plugin authors should now **check for user frontmatter when applying defaults.**
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For example, say a remark plugin wants to apply a default `title` if none is present. Add a conditional to check if the property is present, and update if none exists:
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```diff
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export function remarkInjectTitlePlugin() {
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return function (tree, file) {
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const { frontmatter } = file.data.astro;
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+ if (!frontmatter.title) {
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frontmatter.title = 'Default title';
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+ }
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}
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}
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```
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This differs from previous behavior, where a Markdown file's frontmatter would _always_ override frontmatter injected via remark or reype.
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