如何将文件从 Angular 上传到 ASP.NET Core Web API [英] How to Upload File from Angular to ASP.NET Core Web API
问题描述
有人问过类似的问题,但在浏览了所有这些问题以及有关该主题的许多博客文章后,我一直无法弄清楚这一点,所以请原谅我.
我正在创建一个简单的博客(出于这个问题的目的)两部分,Angular 8 中的前端 SPA 和 ASP.NET Core 3 中的后端 API.在我的前端的一部分中,我是尝试上传图像以用作新创建的博客的图像.当我尝试上传图像时,后端生成的 IFormFile 总是出现 null
.下面是代码,非常感谢任何帮助!
new-blog.component.html:
<div><label for="TileImage">平铺图像标签><input type="file" formControlName="TileImage">
<button type="submit">创建博客</button></表单>
new-blog.component.ts:
import { Component, OnInit } from '@angular/core';从'@angular/forms' 导入 { FormBuilder, FormGroup, FormControl };从 '../blog-services/blog.service' 导入 { BlogService };@成分({选择器:'app-new-blog',templateUrl: './new-blog.component.html',styleUrls: ['./new-blog.component.css']})导出类 NewBlogComponent 实现 OnInit {私人 newBlogForm:FormGroup;构造函数(私有formBuilder:FormBuilder,私有blogService:BlogService){}ngOnInit() {this.newBlogForm = this.formBuilder.group({名称:new FormControl(null),TileImage: 新的 FormControl(null)});}onSubmit(blogData: FormData) {console.log('新博客已提交.', blogData);this.blogService.postBlog(blogData);this.newBlogForm.reset();}}
postBlog
来自 blog.service.ts:
postBlog(blogData: FormData): ObservableSimilar questions have been asked but after looking through all of those and many blog posts on the subject I have not been able to figure this out so please forgive me.
I am creating a simple blog with (for the purposes of this question) two parts, a front end SPA in Angular 8 and a back-end API in ASP.NET Core 3. In one part of my front end I am attempting to upload an image to be used as the image for a newly created blog. When I try to upload an image, the resulting IFormFile in the backend is always coming out to null
. Below is the code, any help is greatly appreciated!
new-blog.component.html:
<form [formGroup]="newBlogForm" (ngSubmit)="onSubmit(newBlogForm.value)">
<div>
<label for="Name">
Blog Name
</label>
<input type="text" formControlName="Name">
</div>
<div>
<label for="TileImage">
Tile Image
</label>
<input type="file" formControlName="TileImage">
</div>
<button type="submit">Create Blog</button>
</form>
new-blog.component.ts:
import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, FormControl } from '@angular/forms';
import { BlogService } from '../blog-services/blog.service';
@Component({
selector: 'app-new-blog',
templateUrl: './new-blog.component.html',
styleUrls: ['./new-blog.component.css']
})
export class NewBlogComponent implements OnInit {
private newBlogForm: FormGroup;
constructor(private formBuilder: FormBuilder, private blogService: BlogService) { }
ngOnInit() {
this.newBlogForm = this.formBuilder.group({
Name: new FormControl(null),
TileImage: new FormControl(null)
});
}
onSubmit(blogData: FormData) {
console.log('new blog has been submitted.', blogData);
this.blogService.postBlog(blogData);
this.newBlogForm.reset();
}
}
postBlog
from blog.service.ts:
postBlog(blogData: FormData): Observable<any> {
const postBlogSubject = new Subject();
this.appOptions.subscribe(
(options) => {
const url = options.blogAPIUrl + '/Blogs';
this.http
.post(url, blogData)
.subscribe(
(blog) => {
postBlogSubject.next(blog);
}
);
}
);
return postBlogSubject.asObservable();
}
The signature for my BlogController looks like this:
[HttpPost]
public async Task<ActionResult<Blog>> PostBlog([FromForm]PostBlogModel blogModel)
with the PostBlogModel as follows:
public class PostBlogModel
{
public string Name { get; set; }
public IFormFile TileImage { get; set; }
}
I have implemented logging middleware to try to debug. The output is as follows (I see that for some reason the front-end is sending application/json rather than multipart/form-data but I'm not sure why or how to fix...)
blogapi_1 | info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
blogapi_1 | Request finished in 170.16740000000001ms 500
blogapi_1 | info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
blogapi_1 | Request starting HTTP/1.1 OPTIONS http://localhost:5432/api/v1/Blogs
blogapi_1 | dbug: BlogAPI.Middleware.RequestResponseLoggingMiddleware[0]
blogapi_1 | HTTP Request: Headers:
blogapi_1 | key: Connection, values: keep-alive
blogapi_1 | key: Accept, values: */*
blogapi_1 | key: Accept-Encoding, values: gzip, deflate, br
blogapi_1 | key: Accept-Language, values: en-US,en-IN;q=0.9,en;q=0.8,en-GB;q=0.7
blogapi_1 | key: Host, values: localhost:5432
blogapi_1 | key: Referer, values: http://localhost:5431/blog/new-blog
blogapi_1 | key: User-Agent, values: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36
blogapi_1 | key: Origin, values: http://localhost:5431
blogapi_1 | key: Access-Control-Request-Method, values: POST
blogapi_1 | key: Access-Control-Request-Headers, values: content-type
blogapi_1 | key: Sec-Fetch-Site, values: same-site
blogapi_1 | key: Sec-Fetch-Mode, values: cors
blogapi_1 |
blogapi_1 | type:
blogapi_1 | scheme: http
blogapi_1 | host+path: localhost:5432/api/v1/Blogs
blogapi_1 | queryString:
blogapi_1 | body:
blogapi_1 | info: Microsoft.AspNetCore.Cors.Infrastructure.CorsService[4]
blogapi_1 | CORS policy execution successful.
blogapi_1 | dbug: BlogAPI.Middleware.RequestResponseLoggingMiddleware[0]
blogapi_1 | HTTP Response: Headers:
blogapi_1 | key: Access-Control-Allow-Headers, values: Content-Type
blogapi_1 | key: Access-Control-Allow-Origin, values: http://localhost:5431
blogapi_1 |
blogapi_1 | statusCode: 204
blogapi_1 | responseBody:
blogapi_1 | info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
blogapi_1 | Request finished in 58.5088ms 204
blogapi_1 | info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
blogapi_1 | Request starting HTTP/1.1 POST http://localhost:5432/api/v1/Blogs application/json 56
blogapi_1 | dbug: BlogAPI.Middleware.RequestResponseLoggingMiddleware[0]
blogapi_1 | HTTP Request: Headers:
blogapi_1 | key: Connection, values: keep-alive
blogapi_1 | key: Content-Type, values: application/json
blogapi_1 | key: Accept, values: application/json, text/plain, */*
blogapi_1 | key: Accept-Encoding, values: gzip, deflate, br
blogapi_1 | key: Accept-Language, values: en-US,en-IN;q=0.9,en;q=0.8,en-GB;q=0.7
blogapi_1 | key: Host, values: localhost:5432
blogapi_1 | key: Referer, values: http://localhost:5431/blog/new-blog
blogapi_1 | key: User-Agent, values: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36
blogapi_1 | key: Origin, values: http://localhost:5431
blogapi_1 | key: Content-Length, values: 56
blogapi_1 | key: Sec-Fetch-Site, values: same-site
blogapi_1 | key: Sec-Fetch-Mode, values: cors
blogapi_1 |
blogapi_1 | type: application/json
blogapi_1 | scheme: http
blogapi_1 | host+path: localhost:5432/api/v1/Blogs
blogapi_1 | queryString:
blogapi_1 | body: {"Name":"test","TileImage":"C:\\fakepath\\DSC_0327.jpg"}
解决方案
my BlogController looks like this:
[HttpPost]
public async Task<ActionResult<Blog>> PostBlog([FromForm]PostBlogModel blogModel)
It seems that you'd like to pass data using form-data, to achieve it, you can refer to the following code sample.
.component.html
<form [formGroup]="newBlogForm" (ngSubmit)="onSubmit(newBlogForm.value)">
<div>
<label for="Name">
Blog Name
</label>
<input type="text" formControlName="Name">
</div>
<div>
<label for="TileImage">
Tile Image
</label>
<input type="file" formControlName="TileImage" (change)="onSelectFile($event)" >
</div>
<button type="submit">Create Blog</button>
</form>
.component.ts
selectedFile: File = null;
private newBlogForm: FormGroup;
constructor(private http: HttpClient) { }
ngOnInit() {
this.newBlogForm = new FormGroup({
Name: new FormControl(null),
TileImage: new FormControl(null)
});
}
onSelectFile(fileInput: any) {
this.selectedFile = <File>fileInput.target.files[0];
}
onSubmit(data) {
const formData = new FormData();
formData.append('Name', data.Name);
formData.append('TileImage', this.selectedFile);
this.http.post('your_url_here', formData)
.subscribe(res => {
alert('Uploaded!!');
});
this.newBlogForm.reset();
}
Test Result
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