Use Partial instead of defining new interface

types/multer/index.d.ts

@@ -6,6 +6,7 @@
 //                 Michael Ledin <https://github.com/mxl>
 //                 HyunSeob Lee <https://github.com/hyunseob>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.1
 
 import * as express from 'express';
 
@@ -48,22 +49,10 @@ declare namespace multer {
     }
 
     interface StorageEngine {
-        _handleFile(req: express.Request, file: Express.Multer.File, callback: (error?: any, info?: FileInfo) => void): void;
+        _handleFile(req: express.Request, file: Express.Multer.File, callback: (error?: any, info?: Partial<Express.Multer.File>) => void): void;
         _removeFile(req: express.Request, file: Express.Multer.File, callback: (error: Error) => void): void;
     }
 
-    interface FileInfo {
-        fieldname?: string;
-        originalname?: string;
-        encoding?: string;
-        mimetype?: string;
-        size?: number;
-        destination?: string;
-        filename?: string;
-        path?: string;
-        buffer?: Buffer;
-    }
-
     interface DiskStorageOptions {
         /** A function used to determine within which folder the uploaded files should be stored. Defaults to the system's default temporary directory. */
         destination?: string | ((req: Express.Request, file: Express.Multer.File, callback: (error: Error | null, destination: string) => void) => void);