@nestjs/common/decorators/http/sse.decorator.js

Nest - modern, fast, powerful node.js web framework (@common)

import { METHOD_METADATA, PATH_METADATA, SSE_METADATA, SSE_OPTIONS_METADATA, } from '../../constants.js';
import { RequestMethod } from '../../enums/request-method.enum.js';
/**
 * Declares this route as a Server-Sent-Events endpoint
 *
 * Events wait in memory for a client that is not reading them. Once more than
 * `maxPendingDataLength` characters of event data (4M by default) wait for a
 * client whose stream is backed up, its connection is dropped. An
 * `EventSource` then reconnects, sending the id of the last event it received.
 * Raise the limit for a route that streams bulk data faster than its clients
 * read, or set it to 0 or `Infinity` to lift it.
 *
 * @param path route path (default: `/`)
 * @param options `SseOptions` object specifying:
 * - `method` - HTTP request method of the route (default: `GET`).
 * - `maxPendingDataLength` - maximum number of characters of event data that
 * may wait for a client that is not reading them (default: 4M). 0 or
 * `Infinity` lifts the limit.
 *
 * @example
 * ```ts
 * @Sse('logs', { maxPendingDataLength: 64 * 1024 * 1024 })
 * logs(): Observable<MessageEvent> { ... }
 * ```
 *
 * @publicApi
 */
export function Sse(path, options = {}) {
    return (target, key, descriptor) => {
        path = path && path.length ? path : '/';
        Reflect.defineMetadata(PATH_METADATA, path, descriptor.value);
        Reflect.defineMetadata(METHOD_METADATA, options[METHOD_METADATA] ?? RequestMethod.GET, descriptor.value);
        Reflect.defineMetadata(SSE_METADATA, true, descriptor.value);
        Reflect.defineMetadata(SSE_OPTIONS_METADATA, { maxPendingDataLength: options.maxPendingDataLength }, descriptor.value);
        return descriptor;
    };
}