Angular: 如何从HttpClient 下载文件？

Question

我需要从我的后端下载一个 excel，它返回了一个文件。

当我执行请求时出现错误：

TypeError: You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.

我的代码是：

this.http.get(`${environment.apiUrl}/...`)
      .subscribe(response => this.downloadFile(response, "application/ms-excel"));

我尝试了 get 和 map(...) 但没有成功。

详情：angular 5.2

参考文献：

import { HttpClient } from '@angular/common/http';
import 'rxjs/add/observable/throw';
import 'rxjs/add/operator/finally';
import 'rxjs/add/operator/map'
import 'rxjs/add/operator/catch';

响应的内容类型：

Content-Type: application/ms-excel

怎么了？

Answer 1

尝试这样的事情：

type: application/ms-excel

/**
 *  used to get file from server
 */

this.http.get(`${environment.apiUrl}`,{
          responseType: 'arraybuffer',headers:headers} 
         ).subscribe(response => this.downLoadFile(response, "application/ms-excel"));


    /**
     * Method is use to download file.
     * @param data - Array Buffer data
     * @param type - type of the document.
     */
    downLoadFile(data: any, type: string) {
        let blob = new Blob([data], { type: type});
        let url = window.URL.createObjectURL(blob);
        let pwa = window.open(url);
        if (!pwa || pwa.closed || typeof pwa.closed == 'undefined') {
            alert( 'Please disable your Pop-up blocker and try again.');
        }
    }

Answer 2

从后端返回带有文件类型的 Blob。以下函数将接受任何文件类型和弹出式下载 window:

downloadFile(route: string, filename: string = null): void{

    const baseUrl = 'http://myserver/index.php/api';
    const token = 'my JWT';
    const headers = new HttpHeaders().set('authorization','Bearer '+token);
    this.http.get(baseUrl + route,{headers, responseType: 'blob' as 'json'}).subscribe(
        (response: any) =>{
            let dataType = response.type;
            let binaryData = [];
            binaryData.push(response);
            let downloadLink = document.createElement('a');
            downloadLink.href = window.URL.createObjectURL(new Blob(binaryData, {type: dataType}));
            if (filename)
                downloadLink.setAttribute('download', filename);
            document.body.appendChild(downloadLink);
            downloadLink.click();
        }
    )
}

Answer 3

在花了很多时间搜索对这个答案的回应之后：如何从我的 API restful 服务器下载一个简单的图像，用 Node.js 编写成 Angular component app，终于在这个网找到了漂亮的答案Angular HttpClient Blob。它主要包括：

API Node.js restful:

   /* After routing the path you want ..*/
  public getImage( req: Request, res: Response) {

    // Check if file exist...
    if (!req.params.file) {
      return res.status(httpStatus.badRequest).json({
        ok: false,
        msg: 'File param not found.'
      })
    }
    const absfile = path.join(STORE_ROOT_DIR,IMAGES_DIR, req.params.file);

    if (!fs.existsSync(absfile)) {
      return res.status(httpStatus.badRequest).json({
        ok: false,
        msg: 'File name not found on server.'
      })
    }
    res.sendFile(path.resolve(absfile));
  }

Angular 6 个经过测试的组件服务（在我的案例中是 EmployeeService）：

  downloadPhoto( name: string) : Observable<Blob> {
    const url = environment.api_url + '/storer/employee/image/' + name;

    return this.http.get(url, { responseType: 'blob' })
      .pipe(
        takeWhile( () => this.alive),
        filter ( image => !!image));
  }

模板

 <img [src]="" class="custom-photo" #photo>

组件订阅者和使用：

@ViewChild('photo') image: ElementRef;

public LoadPhoto( name: string) {
    this._employeeService.downloadPhoto(name)
          .subscribe( image => {
            const url= window.URL.createObjectURL(image);
            this.image.nativeElement.src= url;
          }, error => {
            console.log('error downloading: ', error);
          })    
}

Answer 4

我在使用 post 搜索“rxjs 下载文件”时最终来到这里。

这是我的最终产品。它使用服务器响应中给出的文件名和类型。

import { ajax, AjaxResponse } from 'rxjs/ajax';
import { map } from 'rxjs/operators';

downloadPost(url: string, data: any) {
    return ajax({
        url: url,
        method: 'POST',
        responseType: 'blob',
        body: data,
        headers: {
            'Content-Type': 'application/json',
            'Accept': 'text/plain, */*',
            'Cache-Control': 'no-cache',
        }
    }).pipe(
        map(handleDownloadSuccess),
    );
}


handleDownloadSuccess(response: AjaxResponse) {
    const downloadLink = document.createElement('a');
    downloadLink.href = window.URL.createObjectURL(response.response);

    const disposition = response.xhr.getResponseHeader('Content-Disposition');
    if (disposition) {
        const filenameRegex = /filename[^;=\n]*=((['"]).*?|[^;\n]*)/;
        const matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) {
            const filename = matches[1].replace(/['"]/g, '');
            downloadLink.setAttribute('download', filename);
        }
    }

    document.body.appendChild(downloadLink);
    downloadLink.click();
    document.body.removeChild(downloadLink);
}

Answer 5

我花了一些时间来实现其他响应，因为 我使用的是 Angular 8（最多测试 13）。我最终得到了以下代码（深受 Hasan 的启发）。

请注意，要设置名称，header Access-Control-Expose-Headers 必须包含 Content-Disposition。要在 django RF 中设置它：

http_response = HttpResponse(package, content_type='application/javascript')
http_response['Content-Disposition'] = 'attachment; filename="{}"'.format(filename)
http_response['Access-Control-Expose-Headers'] = "Content-Disposition"

在angular中：

  // component.ts
  // getFileName not necessary, you can just set this as a string if you wish
  getFileName(response: HttpResponse<Blob>) {
    let filename: string;
    try {
      const contentDisposition: string = response.headers.get('content-disposition');
      const r = /(?:filename=")(.+)(?:;")/
      filename = r.exec(contentDisposition)[1];
    }
    catch (e) {
      filename = 'myfile.txt'
    }
    return filename
  }

  
  downloadFile() {
    this._fileService.downloadFile(this.file.uuid)
      .subscribe(
        (response: HttpResponse<Blob>) => {
          let filename: string = this.getFileName(response)
          let binaryData = [];
          binaryData.push(response.body);
          let downloadLink = document.createElement('a');
          downloadLink.href = window.URL.createObjectURL(new Blob(binaryData, { type: 'blob' }));
          downloadLink.setAttribute('download', filename);
          document.body.appendChild(downloadLink);
          downloadLink.click();
        }
      )
  }

  // service.ts
  downloadFile(uuid: string) {
    return this._http.get<Blob>(`${environment.apiUrl}/api/v1/file/${uuid}/package/`, { observe: 'response', responseType: 'blob' as 'json' })
  }

Answer 6

使用 Blob 作为 img 的来源：

模板：

<img [src]="url">

分量：

 public url : SafeResourceUrl;

 constructor(private http: HttpClient, private sanitizer: DomSanitizer) {
   this.getImage('/api/image.jpg').subscribe(x => this.url = x)
 }

 public getImage(url: string): Observable<SafeResourceUrl> {
   return this.http
     .get(url, { responseType: 'blob' })
     .pipe(
       map(x => {
         const urlToBlob = window.URL.createObjectURL(x) // get a URL for the blob
         return this.sanitizer.bypassSecurityTrustResourceUrl(urlToBlob); // tell Anuglar to trust this value
       }),
     );
 }

关于 trusting save values

的进一步参考

Answer 7

使用从 API（Excel 文件）中输出的 Blob

并调整了@gabrielrincon 的回答

downloadExcel(): void {
const payload = {
  order: 'test',
  };

this.service.downloadExcel(payload)
  .subscribe((res: any) => {
    this.blobToFile(res, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "Export.xlsx");
  });}

blob转文件常用函数

blobToFile(data: any, type: string, fileName: string) {
 const a = document.createElement('a');
 document.body.appendChild(a);
 a.style.display = 'none';
 const blob = new Blob([data], { type: type });
 const url = window.URL.createObjectURL(blob);
 a.href = url; a.download = fileName; a.click();
 window.URL.revokeObjectURL(url);}

在 blob 到文件函数中，我们期望第一个参数作为我们的 blob 数据、文件类型和传递文件名，包括扩展名 1。我们正在创建一个 html 标记元素 2。然后我们附加html 中的元素 3. 然后隐藏 a 标签元素 4. 然后用文件和类型创建新的 blob 对象 5. 我们将把 blob 对象转换为 URL 6. 然后附加 URL到我们的 a 标签 7 的 href 属性。我们正在 window 中打开我们的 URL 所以它会下载

Answer 8

可能是我来晚了。但@Hasan 的最后回答非常棒。

我只是做了一些小改动（这不是接受 headers 所以删除了）就成功了。

downloadFile(route: string, filename: string = null): void {
    // const baseUrl = 'http://myserver/index.php/api';   
    this.http.get(route, { responseType: 'blob' }).subscribe(
      (response: any) => {
        let dataType = response.type;
        let binaryData = [];
        binaryData.push(response);
        let downloadLink = document.createElement('a');
        downloadLink.href = window.URL.createObjectURL(new Blob(binaryData, { type: dataType }));
        if (filename) {
          downloadLink.setAttribute('download', filename);
        }
        document.body.appendChild(downloadLink);
        downloadLink.click();
      }
    )
  }

Answer 9

如果你的后端 returns attachment 标志和 filename 属性在它的 Content-Disposition，你可以简单地使这个最简单的 javascript 打电话。

window.location = `${environment.apiUrl}/...`;

浏览器将下载文件而不改变当前页面。

Angular: 如何从HttpClient 下载文件？

Angular: How to download a file from HttpClient?

blob

file

typescript

angular

angular-httpclient