feat: add request note decorator

This extracts the note inserted with the get note interceptor into the request to be used by the controller service.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/api/utils/request-note.decorator.ts

@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import {
+  createParamDecorator,
+  ExecutionContext,
+  InternalServerErrorException,
+} from '@nestjs/common';
+import { Request } from 'express';
+
+import { Note } from '../../notes/note.entity';
+
+/**
+ * Extracts the {@link Note} object from a request
+ *
+ * Will throw an {@link InternalServerErrorException} if no note is present
+ */
+// eslint-disable-next-line @typescript-eslint/naming-convention
+export const RequestNote = createParamDecorator(
+  (data: unknown, ctx: ExecutionContext) => {
+    const request: Request & { note: Note } = ctx.switchToHttp().getRequest();
+    if (!request.note) {
+      // We should have a note here, otherwise something is wrong
+      throw new InternalServerErrorException(
+        'Request is missing a note object',
+      );
+    }
+    return request.note;
+  },
+);