astro/dist/core/middleware/load.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { createOriginCheckMiddleware } from "../app/origin-check.js";
import { createAsyncManifestMemo } from "../manifest/memo.js";
import { NOOP_MIDDLEWARE_FN } from "./noop-middleware.js";
import { sequence } from "./sequence.js";
// Snapshot of the already-resolved middleware, for the sync `peekMiddleware`
// accessor (reproduces `ContainerPipeline.insertRoute`'s synchronous
// `this.resolvedMiddleware` read).
const resolvedMiddleware = new WeakMap();
const middlewareMemo = createAsyncManifestMemo(async (manifest) => {
	let handler;
	// The middleware can be undefined when using edge middleware.
	// This is set to undefined by the plugin-ssr.ts
	if (manifest.middleware) {
		const middlewareInstance = await manifest.middleware();
		const onRequest = middlewareInstance.onRequest ?? NOOP_MIDDLEWARE_FN;
		const internalMiddlewares = [onRequest];
		if (manifest.checkOrigin) {
			// this middleware must be placed at the beginning because it needs to block incoming requests
			internalMiddlewares.unshift(createOriginCheckMiddleware());
		}
		handler = sequence(...internalMiddlewares);
	} else {
		handler = NOOP_MIDDLEWARE_FN;
	}
	resolvedMiddleware.set(manifest, handler);
	return handler;
});
/**
* Resolves the middleware from the manifest and returns the `onRequest`
* function (prefixed with the origin-check middleware when configured). If
* `onRequest` isn't there, it returns a no-op function.
*/
export function getMiddleware(manifest) {
	return middlewareMemo.get(manifest);
}
/**
* The already-resolved middleware for a manifest, or `undefined` when
* `getMiddleware` has not settled yet. Sync — used where a synchronous
* snapshot is required (the container's `insertRoute`).
*/
export function peekMiddleware(manifest) {
	return resolvedMiddleware.get(manifest);
}
/**
* Clears the cached middleware so it is re-resolved on the next request.
* Called via HMR when middleware files change during development.
*/
export function clearMiddleware(manifest) {
	middlewareMemo.invalidate(manifest);
	resolvedMiddleware.delete(manifest);
}