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184 lines
8.9 KiB
Markdown
184 lines
8.9 KiB
Markdown
---
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layout: ~/layouts/MainLayout.astro
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title: API Reference
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---
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## `Astro` global
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The `Astro` global is available in all contexts in `.astro` files. It has the following functions:
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### `Astro.fetchContent()`
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`Astro.fetchContent()` is a way to load local `*.md` files into your static site setup. You can either use this on its own, or within [Astro Collections](/core-concepts/collections).
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```jsx
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// ./src/components/my-component.astro
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---
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const data = Astro.fetchContent('../pages/post/*.md'); // returns an array of posts that live at ./src/pages/post/*.md
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---
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<div>
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{data.slice(0, 3).map((post) => (
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<article>
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<h1>{post.title}</h1>
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<p>{post.description}</p>
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<a href={post.url}>Read more</a>
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</article>
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))}
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</div>
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```
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`.fetchContent()` only takes one parameter: a relative URL glob of which local files you'd like to import. Currently only `*.md` files are supported. It's synchronous, and returns an array of items of type:
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```js
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{
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/** frontmatter from the post.. example frontmatter:
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title: '',
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tag: '',
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date: '',
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image: '',
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author: '',
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description: '',
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**/
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astro: {
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headers: [], // an array of h1...h6 elements in the markdown file
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source: '', // raw source of the markdown file
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html: '' // rendered HTML of the markdown file
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},
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url: '' // the rendered path
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}[]
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```
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### `Astro.request`
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`Astro.request` returns an object with the following properties:
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| Name | Type | Description |
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| :------------- | :---- | :---------------------------------------------- |
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| `url` | `URL` | The URL of the request being rendered. |
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| `canonicalURL` | `URL` | [Canonical URL][canonical] of the current page. |
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⚠️ Temporary restriction: this is only accessible in top-level pages and not in sub-components.
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### `Astro.site`
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`Astro.site` returns a `URL` made from `buildOptions.site` in your Astro config. If undefined, this will return a URL generated from `localhost`.
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## Collections API
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### `collection` prop
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```jsx
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const { collection } = Astro.props;
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```
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When using the [Collections API](/core-concepts/collections), `collection` is a prop exposed to the page with the following shape:
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| Name | Type | Description |
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| :------------------------ | :-------------------: | :-------------------------------------------------------------------------------------------------------------------------------- |
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| `collection.data` | `Array` | Array of data returned from `data()` for the current page. |
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| `collection.start` | `number` | Index of first item on current page, starting at `0` (e.g. if `pageSize: 25`, this would be `0` on page 1, `25` on page 2, etc.). |
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| `collection.end` | `number` | Index of last item on current page. |
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| `collection.total` | `number` | The total number of items across all pages. |
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| `collection.page.current` | `number` | The current page number, starting with `1`. |
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| `collection.page.size` | `number` | How many items per-page. |
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| `collection.page.last` | `number` | The total number of pages. |
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| `collection.url.current` | `string` | Get the URL of the current page (useful for canonical URLs) |
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| `collection.url.prev` | `string \| undefined` | Get the URL of the previous page (will be `undefined` if on page 1). |
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| `collection.url.next` | `string \| undefined` | Get the URL of the next page (will be `undefined` if no more pages). |
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| `collection.params` | `object` | If page params were used, this returns a `{ key: value }` object of all values. |
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### `createCollection()`
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```jsx
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export async function createCollection() {
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return {
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async data({ params }) {
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// load data
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},
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pageSize: 25,
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routes: [{ tag: 'movie' }, { tag: 'television' }],
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permalink: ({ params }) => `/tag/${params.tag}`,
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};
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}
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```
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When using the [Collections API](/core-concepts/collections), `createCollection()` is an async function that returns an object of the following shape:
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| Name | Type | Description |
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| :---------- | :--------------------------------------: | :--------------------------------------------------------------------------------------------------------- |
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| `data` | `async ({ params }) => any[]` | **Required.** Load an array of data with this function to be returned. |
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| `pageSize` | `number` | Specify number of items per page (default: `25`). |
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| `routes` | `params[]` | **Required for URL Params.** Return an array of all possible URL `param` values in `{ name: value }` form. |
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| `permalink` | `({ params }) => string` | **Required for URL Params.** Given a `param` object of `{ name: value }`, generate the final URL.\* |
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| `rss` | [RSS](/reference/api-reference#rss-feed) | Optional: generate an RSS 2.0 feed from this collection ([docs](/reference/api-reference#rss-feed)) |
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_\* Note: don't create confusing URLs with `permalink`, e.g. rearranging params conditionally based on their values._
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⚠️ `createCollection()` executes in its own isolated scope before page loads. Therefore you can't reference anything from its parent scope. If you need to load data you may fetch or use async `import()`s within the function body for anything you need (that's why it's `async`—to give you this ability). If it wasn't isolated, then `collection` would be undefined! Therefore, duplicating imports between `createCollection()` and your Astro component is OK.
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#### RSS Feed
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You can optionally generate an RSS 2.0 feed from `createCollection()` by adding an `rss` option. Here are all the options:
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```jsx
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export async function createCollection() {
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return {
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async data({ params }) {
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// load data
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},
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pageSize: 25,
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rss: {
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title: 'My RSS Feed',
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description: 'Description of the feed',
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/** (optional) add xmlns:* properties to root element */
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xmlns: {
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itunes: 'http://www.itunes.com/dtds/podcast-1.0.dtd',
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content: 'http://purl.org/rss/1.0/modules/content/',
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},
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/** (optional) add arbitrary XML to <channel> */
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customData: `<language>en-us</language>
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<itunes:author>The Sunset Explorers</itunes:author>`,
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/** Format each item from things returned in data() */
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item: (item) => ({
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title: item.title,
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description: item.description,
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pubDate: item.pubDate + 'Z', // enforce GMT timezone (otherwise it'll be different based on where it's built)
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/** (optional) add arbitrary XML to each <item> */
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customData: `<itunes:episodeType>${item.type}</itunes:episodeType>
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<itunes:duration>${item.duration}</itunes:duration>
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<itunes:explicit>${item.explicit || false}</itunes:explicit>`,
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}),
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},
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};
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}
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```
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Astro will generate an RSS 2.0 feed at `/feed/[collection].xml` (for example, `/src/pages/$podcast.xml` would generate `/feed/podcast.xml`).
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⚠️ Even though Astro will create the RSS feed for you, you'll still need to add `<link>` tags manually in your `<head>` HTML:
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```html
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<link
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rel="alternate"
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type="application/rss+xml"
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title="My RSS Feed"
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href="/feed/podcast.xml"
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/>
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```
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## `import.meta`
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All ESM modules include a `import.meta` property. Astro adds `import.meta.env` through [Snowpack](https://www.snowpack.dev/).
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**import.meta.env.SSR** can be used to know when rendering on the server. Sometimes you might want different logic, for example a component that should only be rendered in the client:
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```jsx
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import { h } from 'preact';
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export default function () {
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return import.meta.env.SSR ? <div class="spinner"></div> : <FancyComponent />;
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}
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```
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[canonical]: https://en.wikipedia.org/wiki/Canonical_link_element
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