Nodejs multer angular file upload error发送头后无法设置头

使用角度5节点和Multer 我正在尝试上载文件,因此首先我尝试将文件获取到某个目录,然后必须将该路径插入数据库, 所以首先我创建了表单

<input type="file" (change)="onFileSelected($event)">
<button type="button" (click)="onUpload()">Upload</button>

在那之后,我在我的。ts文件

onFileSelected(event){
   this.selectedFile = event.target.files[0];
  }

onUpload(){
    var fd = new FormData();
    fd.append('productImage',  this.selectedFile, this.selectedFile.name);
    this.httpClient.post('http://localhost:3000/uploadImage/1', fd )
    .subscribe(res => {
      console.log(res);
    });
  }

我的节点rest调用如下

app.post('/uploadImage/:id', upload.single("productImage")  ,(request, result) => {
    result.send(request.file);
    result.send(request.params.id);
    result.send("Done");
});

我感到困惑的部分是,因为我正在节点端设置标头,如何将其从前端删除,以避免出现以下错误,即发送标头时无法设置标头

Error: Can't set headers after they are sent.
    at validateHeader (_http_outgoing.js:494:11)
    at ServerResponse.setHeader (_http_outgoing.js:501:3)
    at ServerResponse.header (D:\Projects\Craiglist\api\node_modules\express\lib\response.js:767:10)
    at ServerResponse.contentType (D:\Projects\Craiglist\api\node_modules\express\lib\response.js:595:15)
    at ServerResponse.send (D:\Projects\Craiglist\api\node_modules\express\lib\response.js:145:14)
    at app.post (D:\Projects\Craiglist\api\index.js:41:12)
    at Layer.handle [as handle_request] (D:\Projects\Craiglist\api\node_modules\express\lib\router\layer.js:95:5)
    at next (D:\Projects\Craiglist\api\node_modules\express\lib\router\route.js:137:13)
    at Array.<anonymous> (D:\Projects\Craiglist\api\node_modules\multer\lib\make-middleware.js:53:37)
    at listener (D:\Projects\Craiglist\api\node_modules\on-finished\index.js:169:15)