Hi, I'm writing a table of contents component for my markdoc articles. I want to figure out how to access the headings array for this.
#Rendered markdown doc form Component
untold hill
rare badgerBOT
Hi @untold hill. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:
To access the headings from a markdown or markdoc file in Astro, you can use the getHeadings function that is available when you import the file. This function returns an array of all headings (i.e., h1 to h6 elements) in the file. Each heading’s slug corresponds to the generated ID for a given heading and can be used for anchor links. The list follows the type: { depth: number; slug: string; text: string }[].
Here is an example of how you can use it:
import { getEntryBySlug } from 'astro:content';
const entry = await getEntryBySlug('blog', 'post-1');
const { Content, getHeadings } = entry;
const headings = await getHeadings();
console.log(headings) // Outputs the array of headings
In this example, getEntryBySlug is used to get the specific markdown or markdoc file. The getHeadings function is then called to get the array of headings.
Please note that as of Astro version 2.3.0, getting headings from a markdoc file using the render() method might return an empty object. This issue is expected to be addressed in a future patch release.
For more information, you can refer to the Astro documentation on Markdown & MDX (https://docs.astro.build/en/guides/markdown-content#exported-properties) and the Astro documentation on Markdoc (https://docs.astro.build/en/guides/integrations-guide/markdoc#access-frontmatter-from-your-markdoc-content).
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untold hill
@rare badger Maybe I'm misunderstanding how this works. I in my pages/articles/[slug].astro I render the headings and they seem to be redering correctly. (const { Content, headings } = await entry.render();) Then I pass them through as variables to the markdoc as Layout attributes (<Layout meta={Astro.props} headings={headings}>). That works great for the page props -- and I'm able to pass the object into components as an attribute like: {% toc meta=$meta headings=$headings /%}
Now the probme is, that in my TOC.astro component, I'm able to access the meta object, but the headings is empty:
console.log('meta', Astro.props.meta);
console.log('headings', Astro.props.headings);
I've properly defined the fields for the object in the markdoc.config.js
'toc': {
render: component('./src/components/article/TOC.astro'),
attributes: {
meta: { type: Object, required: false, default: {} },
headings: { type: Array, required: true, default: [] },
},
},
rare badgerBOT
Let me check the knowledge base for you. One moment! :books:
Based on the information provided, it seems like you're correctly passing the headings from your page to the Layout component. However, there are a few things that could be causing the headings to be empty in your TOC.astro component.
-
Issue with
render()method: As per the Github issue #6855 (https://github.com/withastro/astro/issues/6855), there's a known issue where getting headings from a markdoc file using therender()method returns an empty object. This issue was reported for Astro version 2.3.0 and might still be present in the version you're using. -
Markdoc configuration: In your
markdoc.config.js, you've defined theheadingsattribute as an array. Ensure that theheadingsyou're passing from your page is indeed an array. If it's not, it might be causing the issue. -
Accessing
headingsinTOC.astro: In yourTOC.astrocomponent, you're trying to accessAstro.props.headings. Ensure thatheadingsis being passed correctly to this component. If it's not, it would result in an empty output.
If you're still facing the issue, I would recommend checking the version of Astro you're using and updating it if necessary. Also, consider checking the Astro and Markdoc documentation or the Astro Github issues for any updates or solutions related to this issue.
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
untold hill
@rare badger Can you give me an example of how one would create a TOC component?
rare badgerBOT
Let me check the knowledge base for you. One moment! :books:
Based on the information provided in the extracts, I can provide a general idea of how to create a Table of Contents (TOC) component in Astro. However, please note that the specific implementation might vary based on your project's structure and requirements.
Here's a basic example of how you might structure a TOC component:
---
// Import any necessary components or libraries
---
const { headings } = Astro.props;
<ul>
{headings.map((heading) => (
<li>
<a href={`#${heading.slug}`}>{heading.text}</a>
</li>
))}
</ul>
In this example, headings is a prop that you would pass to the TOC component. Each heading object in the headings array should have a slug and text property. The slug is used to create a link to the corresponding heading, and the text is used as the link's text.
You would use this TOC component in another component or page like so:
---
import TOC from '../components/TOC.astro';
const { Content, getHeadings } = await entry.render();
const headings = await getHeadings();
---
<Content />
<TOC headings={headings} />
In this example, getHeadings is a function that you get when you render a markdown or markdoc file. You call getHeadings to get an array of all the headings in the file, and then pass this array to the TOC component.
Please note that this is a simplified example and might not cover all use cases. For more detailed information, you might want to refer to the Astro documentation (https://docs.astro.build).
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
untold hill
@rare badger but how would this work in a component for a markdoc article?
rare badgerBOT
Let me check the knowledge base for you. One moment! :books:
To use a Table of Contents (TOC) component in a Markdoc article, you would need to define a custom tag in your markdoc.config.mjs file that maps to your TOC component. Then, you can use this tag in your Markdoc files.
Here's an example of how you might define the TOC tag in your markdoc.config.mjs file:
import { defineMarkdocConfig, component } from '@astrojs/markdoc/config';
export default defineMarkdocConfig({
tags: {
toc: {
render: component('./src/components/TOC.astro'),
attributes: {
headings: { type: Array, required: true, default: [] },
},
},
},
});
In this example, toc is the name of the custom tag, and it maps to the TOC.astro component. The headings attribute is defined as an array, which matches the prop that the TOC component expects.
Then, in your Markdoc files, you can use the {% toc %} tag to render the TOC component. You would need to pass the headings as an attribute to the tag:
{% toc headings=$headings %}
In this example, $headings is a variable that contains the array of headings. You would need to define this variable in your Markdoc file.