使用HttpClient上传图片

Question

问题

我尝试将带有角度的图像上传HttpClient到API Content-Type: multipart/form-data(角度v4 +).是否支持？怎么做？

上传适用于XMLHttpRequest使用模块时ng2-fancy-image-uploader.我更喜欢使用自定义方法HttpClient,我可以将其与其他访问API的方法一起放入http服务中.

这是我到目前为止所尝试的:

model.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders, HttpResponse } from '@angular/common/http';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class ModelService {
  constructor(private http: HttpClient) { }

  public async updateAvatar(file: File): Promise<void> {

    // headers
    const headers = new HttpHeaders()
      .append('Content-Type', 'multipart/form-data');

    const formData: FormData = new FormData();
    formData.append('avatar', file, file.name);

    const response: HttpResponse = await this.http
      .patch('https://example.com/avatar', formData, { headers, observe: 'response' })
      .toPromise();

    console.log(response.status);
  }
}

化身uploader.component.ts

import { Component, ElementRef, OnInit, ViewChild } from '@angular/core';
import { ModelService } from './path/to/model.service';

@Component({
  selector: 'app-avatar-uploader',
  template: '<input type="file" #fileInput (changes)="uploadAvatar()">'
})
export class AvatarUploaderComponent implements OnInit {

  @ViewChild('fileInput') fileInputElement: ElementRef;

  constructor() { }

  ngOnInit() { }

  public async uploadAvatar() {
    const file: File = this.fileInputElement.nativeElement.files[0];

    await this.model.updateAvatar(file);
  }

}

此版本向(表达)API发送请求,但multer(用于解析multipart/form-data请求的库)无法解析请求.

所以我想我要么使用HttpClient不正确,要么不支持multipart/form-data请求.

我猜一个人可以发送base64编码的文件或使用XmlHttpRequest,但我特别要求HttpClient它能够做到这一点.

Answer 1

对我来说,诀窍不是将内容类型设置为multipart/form-data.但那是我自动完成的.

<label>
  <input type="file" (change)="setFiles($event)" style="display:none" multiple/>
  <a mat-raised-button color="primary">
    <mat-icon>file_upload</mat-icon>
    Select Documents
  </a>
</label>

这是我上传multipart/form-data的代码.无需设置标题.

private setFile(event) {
    let files = event.srcElement.files
    if (!files) {
      return
    }

    let path = `${environment.celoApiEndpoint}/api/patientFiles`
    let data = {"patientData": {
      "uid": "",
      "firstName": "",
      "lastName": "",
      "gender": "Not Specified",
      "dateOfBirth": ""
    }}
    // let headers = new HttpHeaders()
    //   .set('content-type', 'multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW')
    // let headers = new HttpHeaders().set('content-type', 'multipart/form-data')
    const formData: FormData = new FormData();

    for (let i = 0; i < files.length; i++) {
      formData.append(i.toString(), files[i], files[i].name);
    }
    formData.append("data", JSON.stringify(data));
    this.http.post(path, formData).subscribe(
      (r)=>{console.log('got r', r)}
    )
  }

Answer 2

我不认为问题出在角度上，我使用相同的代码将文件发送到服务器（我在后端使用 spring），唯一的区别是我没有观察请求或将响应转换为承诺。

请参阅下面我的代码：

let formData: FormData = new FormData();
formData.append('file', this.fileToUpload);

this.http.put(this.usersUrl, formData).subscribe(
    data => {
        console.log(data); 
    },
    error => {
        console.log(error);
    }
);