File Upload with Angular2 to REST API

This is actually really easy to do in the final release. Took me a while to wrap my head around it because most information about it that I've come across is outdated. Posting my solution here in case anyone else is struggling with this.

import { Component, ElementRef, Input, ViewChild } from '@angular/core';
import { Http } from '@angular/http';

@Component({
    selector: 'file-upload',
    template: '<input type="file" [multiple]="multiple" #fileInput>'
})
export class FileUploadComponent {
    @Input() multiple: boolean = false;
    @ViewChild('fileInput') inputEl: ElementRef;

    constructor(private http: Http) {}

    upload() {
        let inputEl: HTMLInputElement = this.inputEl.nativeElement;
        let fileCount: number = inputEl.files.length;
        let formData = new FormData();
        if (fileCount > 0) { // a file was selected
            for (let i = 0; i < fileCount; i++) {
                formData.append('file[]', inputEl.files.item(i));
            }
            this.http
                .post('http://your.upload.url', formData)
                // do whatever you do...
                // subscribe to observable to listen for response
        }
    }
}

Then just use it like so:

<file-upload #fu (change)="fu.upload()" [multiple]="true"></file-upload>

That is really all there is to it.

Alternatively, capture the event object and get the files from the srcElement. Not sure if any way is better than the other, to be honest!

Keep in mind FormData is IE10+, so if you have to support IE9 you'll need a polyfill.

Update 2017-01-07

Updated code to be able to handle uploading of multiple files. Also my original answer was missing a rather crucial bit concerning FormData (since I moved the actual upload logic to a separate service in my own app I was handling it there).

In fact, at the moment, you can only provide string input for post, put and patch methods of the Angular2 HTTP support.

To support that, you need to leverage the XHR object directly, as described below:

import {Injectable} from 'angular2/core';
import {Observable} from 'rxjs/Rx';

@Injectable()
export class UploadService {
  constructor () {
    this.progress$ = Observable.create(observer => {
      this.progressObserver = observer
    }).share();
  }

  private makeFileRequest (url: string, params: string[], files: File[]): Observable {
    return Observable.create(observer => {
      let formData: FormData = new FormData(),
        xhr: XMLHttpRequest = new XMLHttpRequest();

      for (let i = 0; i < files.length; i++) {
        formData.append("uploads[]", files[i], files[i].name);
      }

      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4) {
          if (xhr.status === 200) {
            observer.next(JSON.parse(xhr.response));
            observer.complete();
          } else {
            observer.error(xhr.response);
          }
        }
      };

      xhr.upload.onprogress = (event) => {
        this.progress = Math.round(event.loaded / event.total * 100);

        this.progressObserver.next(this.progress);
      };

      xhr.open('POST', url, true);
      xhr.send(formData);
    });
  }
}

See this plunkr for more details: https://plnkr.co/edit/ozZqbxIorjQW15BrDFrg?p=info.

There is a an issue and a pending PR regarding this in the Angular repo:

• https://github.com/angular/angular/issues/10424
• https://github.com/angular/angular/pull/7310/files

This has worked for me:

<input type="file" (change)="onChange($event)" required class="form-control " name="attach_file" id="attach_file">
onChange(event: any) {
    let fileList: FileList = event.target.files;
if(fileList.length > 0) {
    let file: File = fileList[0];
    let formData:FormData = new FormData();
    formData.append('degree_attachment', file, file.name);
    let headers = new Headers();
    headers.append('Accept', 'application/json');
    let options = new RequestOptions({ headers: headers });
    this.http.post('http://url', formData,options)
        .map(res => res.json())
        .catch(error => Observable.throw(error))
        .subscribe(
            data => console.log('success'),
            error => console.log(error)
        )
}}

This has worked for me: Angular 2 provides good support to upload file:

<input type="file" (change)="fileChange($event)" placeholder="Upload file" accept=".pdf,.doc,.docx">

fileChange(event) {
    let fileList: FileList = event.target.files;
    if(fileList.length > 0) {
        let file: File = fileList[0];
        let formData:FormData = new FormData();
        formData.append('uploadFile', file, file.name);
        let headers = new Headers();
        headers.append('Content-Type', 'multipart/form-data');
        headers.append('Accept', 'application/json');
        let options = new RequestOptions({ headers: headers });
        this.http.post(URL, formData, options)
            .map(res => res.json())
            .catch(error => Observable.throw(error))
            .subscribe(
                data => console.log('success'),
                error => console.log(error)
            )
    }
}

I was getting error : java.io.IOException: RESTEASY007550: Unable to get boundary for multipart

In order to solve this you should remove the "Content-Type" "multipart/form-data"