[koa__multer] Allows to access the properties file and files through the koa context. (#40034)

* [koa__multer] Allows to access the file nad files through the koa contet.

* Extends the koa context and request by the fields file, files.

* Removes unecessary import

types/koa__multer/index.d.ts

@@ -19,6 +19,11 @@
  * async function uploadFile(ctx: Koa.Context){
  *     let multerReq = <multer.MulterIncomingMessage>ctx.req;
  *     let files = multerReq.files;
+ *
+ *     // You can also directly access the files property from the context object or request object:
+ *     files = ctx.files;
+ *     files = ctx.request.files;
+ *
  *     let baseFilePath: string = ctx.params.path || '';
  *     //...
  * }
@@ -32,6 +37,18 @@
 import * as Koa from 'koa';
 import { IncomingMessage } from 'http';
 
+declare module 'koa' {
+    interface DefaultContext {
+        file: multer.File;
+        files: multer.File[];
+    }
+
+    interface Request {
+        file: multer.File;
+        files: multer.File[];
+    }
+}
+
 declare namespace multer {
     interface File {
         /** Field name specified in the form */

types/koa__multer/koa__multer-tests.ts

@@ -13,6 +13,12 @@ const app = new Koa();
 app.use(upload.single('avatar'));
 
 app.use(upload.array('photos', 12));
+app.use(async (ctx, next) => {
+    for (const file of ctx.request.files) {
+        console.info(`Received file: ${file.filename}`);
+    }
+    await next();
+});
 
 const cpUpload = upload.fields([{ name: 'avatar', maxCount: 1 }, { name: 'gallery', maxCount: 8 }]);
 app.use(cpUpload);