我是Angular的初学者，我想知道如何创建Angular 5文件上传部分，我试图找到任何教程或文档，但我在任何地方都看不到任何东西。对此有什么想法吗?我尝试了ng4-files，但它不适用于Angular 5
当前回答
我使用的是Angular 5.2.11， 我喜欢Gregor Doroschenko提供的解决方案，但是我注意到上传的文件是零字节的，我必须做一个小小的改变才能让它为我工作。
postFile(fileToUpload: File): Observable<boolean> {
const endpoint = 'your-destination-url';
return this.httpClient
.post(endpoint, fileToUpload, { headers: yourHeadersConfig })
.map(() => { return true; })
.catch((e) => this.handleError(e));
}
下面几行(formData)对我不起作用。
const formData: FormData = new FormData();
formData.append('fileKey', fileToUpload, fileToUpload.name);
https://github.com/amitrke/ngrke/blob/master/src/app/services/fileupload.service.ts
其他回答
我使用的是Angular 5.2.11， 我喜欢Gregor Doroschenko提供的解决方案，但是我注意到上传的文件是零字节的，我必须做一个小小的改变才能让它为我工作。
postFile(fileToUpload: File): Observable<boolean> {
const endpoint = 'your-destination-url';
return this.httpClient
.post(endpoint, fileToUpload, { headers: yourHeadersConfig })
.map(() => { return true; })
.catch((e) => this.handleError(e));
}
下面几行(formData)对我不起作用。
const formData: FormData = new FormData();
formData.append('fileKey', fileToUpload, fileToUpload.name);
https://github.com/amitrke/ngrke/blob/master/src/app/services/fileupload.service.ts
通过这种方式，我实现了在项目中上传文件到web API。
我为谁分担关心。
const formData: FormData = new FormData();
formData.append('Image', image, image.name);
formData.append('ComponentId', componentId);
return this.http.post('/api/dashboard/UploadImage', formData);
一步一步
ASP。网上广告
[HttpPost]
[Route("api/dashboard/UploadImage")]
public HttpResponseMessage UploadImage()
{
string imageName = null;
var httpRequest = HttpContext.Current.Request;
//Upload Image
var postedFile = httpRequest.Files["Image"];
//Create custom filename
if (postedFile != null)
{
imageName = new String(Path.GetFileNameWithoutExtension(postedFile.FileName).Take(10).ToArray()).Replace(" ", "-");
imageName = imageName + DateTime.Now.ToString("yymmssfff") + Path.GetExtension(postedFile.FileName);
var filePath = HttpContext.Current.Server.MapPath("~/Images/" + imageName);
postedFile.SaveAs(filePath);
}
}
HTML表单
<form #imageForm=ngForm (ngSubmit)="OnSubmit(Image)">
<img [src]="imageUrl" class="imgArea">
<div class="image-upload">
<label for="file-input">
<img src="upload.jpg" />
</label>
<input id="file-input" #Image type="file" (change)="handleFileInput($event.target.files)" />
<button type="submit" class="btn-large btn-submit" [disabled]="Image.value=='' || !imageForm.valid"><i
class="material-icons">save</i></button>
</div>
</form>
TS文件使用API
OnSubmit(Image) {
this.dashboardService.uploadImage(this.componentId, this.fileToUpload).subscribe(
data => {
console.log('done');
Image.value = null;
this.imageUrl = "/assets/img/logo.png";
}
);
}
服务TS
uploadImage(componentId, image) {
const formData: FormData = new FormData();
formData.append('Image', image, image.name);
formData.append('ComponentId', componentId);
return this.http.post('/api/dashboard/UploadImage', formData);
}
在Angular 7/8/9中
来源链接
使用自举表单
<form>
<div class="form-group">
<fieldset class="form-group">
<label>Upload Logo</label>
{{imageError}}
<div class="custom-file fileInputProfileWrap">
<input type="file" (change)="fileChangeEvent($event)" class="fileInputProfile">
<div class="img-space">
<ng-container *ngIf="isImageSaved; else elseTemplate">
<img [src]="cardImageBase64" />
</ng-container>
<ng-template #elseTemplate>
<img src="./../../assets/placeholder.png" class="img-responsive">
</ng-template>
</div>
</div>
</fieldset>
</div>
<a class="btn btn-danger" (click)="removeImage()" *ngIf="isImageSaved">Remove</a>
</form>
在组件类中
fileChangeEvent(fileInput: any) {
this.imageError = null;
if (fileInput.target.files && fileInput.target.files[0]) {
// Size Filter Bytes
const max_size = 20971520;
const allowed_types = ['image/png', 'image/jpeg'];
const max_height = 15200;
const max_width = 25600;
if (fileInput.target.files[0].size > max_size) {
this.imageError =
'Maximum size allowed is ' + max_size / 1000 + 'Mb';
return false;
}
if (!_.includes(allowed_types, fileInput.target.files[0].type)) {
this.imageError = 'Only Images are allowed ( JPG | PNG )';
return false;
}
const reader = new FileReader();
reader.onload = (e: any) => {
const image = new Image();
image.src = e.target.result;
image.onload = rs => {
const img_height = rs.currentTarget['height'];
const img_width = rs.currentTarget['width'];
console.log(img_height, img_width);
if (img_height > max_height && img_width > max_width) {
this.imageError =
'Maximum dimentions allowed ' +
max_height +
'*' +
max_width +
'px';
return false;
} else {
const imgBase64Path = e.target.result;
this.cardImageBase64 = imgBase64Path;
this.isImageSaved = true;
// this.previewImagePath = imgBase64Path;
}
};
};
reader.readAsDataURL(fileInput.target.files[0]);
}
}
removeImage() {
this.cardImageBase64 = null;
this.isImageSaved = false;
}
下面是一个上传文件到api的例子:
步骤1:HTML模板
定义文件类型的简单输入标记。为(change)-event添加一个处理选择文件的函数。
<div class="form-group">
<label for="file">Choose File</label>
<input type="file"
id="file"
(change)="handleFileInput($event.target.files)">
</div>
步骤2:在TypeScript中处理上传
为所选文件定义一个默认变量。
fileToUpload: File | null = null;
创建你在(change)-event中使用的函数:
handleFileInput(files: FileList) {
this.fileToUpload = files.item(0);
}
如果你想处理多文件选择，那么你可以遍历这个文件数组。
现在通过调用file-upload.service创建文件上传函数:
uploadFileToActivity() {
this.fileUploadService.postFile(this.fileToUpload).subscribe(data => {
// do something, if upload success
}, error => {
console.log(error);
});
}
第三步:文件上传服务
通过post方法上传文件，你应该使用FormData，因为这样你可以添加文件到http请求。
postFile(fileToUpload: File): Observable<boolean> {
const endpoint = 'your-destination-url';
const formData: FormData = new FormData();
formData.append('fileKey', fileToUpload, fileToUpload.name);
return this.httpClient
.post(endpoint, formData, { headers: yourHeadersConfig })
.map(() => { return true; })
.catch((e) => this.handleError(e));
}
所以，这是一个非常简单的工作例子，我每天都在工作中使用。
create-profile.html
<body>
<h1 class="font-weight-bold" >Create Advertistment</h1>
<hr />
<form [formGroup]="form" (submit)="onSubmit()">
<div>
<label class="font-weight-bold">Insert Subject name</label>
<br>
<input formControlName="name" type="text" placeholder="Enter name..." />
</div>
<div>
<br>
<label class="font-weight-bold">Select the Advertistment</label>
<br>
<input (change)="onFileSelect($event)" type="file" />
</div>
<br>
<!--<div *ngIf="imageData">
<img [src]="imageData" [alt]="form.value.name" />
</div>-->
<div>
<label class="font-weight-bold">Upload the Advertistment</label>
<br>
<button type="submit" class="btn btn-success" >Upload Advertistment</button>
</div>
</form>
</body>
create-profile.ts
import { Component, OnInit } from "@angular/core";
import { FormGroup, FormControl } from "@angular/forms";
import { Profile } from "../../models/Profile";
import { ProfileService } from "src/app/services/profile.service";
@Component({
selector: "app-create-profile",
templateUrl: "./create-profile.component.html",
styleUrls: ["./create-profile.component.css"],
})
export class CreateProfileComponent implements OnInit {
form: FormGroup;
profile: Profile;
imageData: string;
constructor(private profileService: ProfileService) {}
ngOnInit(): void {
this.form = new FormGroup({
name: new FormControl(null),
image: new FormControl(null),
});
}
onFileSelect(event: Event) {
const file = (event.target as HTMLInputElement).files[0];
this.form.patchValue({ image: file });
const allowedMimeTypes = ["image/png", "image/jpeg", "image/jpg"];
if (file && allowedMimeTypes.includes(file.type)) {
const reader = new FileReader();
reader.onload = () => {
this.imageData = reader.result as string;
};
reader.readAsDataURL(file);
}
}
onSubmit() {
this.profileService.addProfile(this.form.value.name, this.form.value.image);
this.form.reset();
this.imageData = null;
}
}
profile.service.ts
import { Injectable } from "@angular/core";
import { HttpClient } from "@angular/common/http";
import { map } from "rxjs/operators";
import { Profile } from "../models/Profile";
import { Subject } from "rxjs";
@Injectable({
providedIn: "root",
})
export class ProfileService {
private profiles: Profile[] = [];
private profiles$ = new Subject<Profile[]>();
readonly url = "http://localhost:3000/api/profiles";
constructor(private http: HttpClient) {}
getProfiles() {
this.http
.get<{ profiles: Profile[] }>(this.url)
.pipe(
map((profileData) => {
return profileData.profiles;
})
)
.subscribe((profiles) => {
this.profiles = profiles;
this.profiles$.next(this.profiles);
});
}
getProfilesStream() {
return this.profiles$.asObservable();
}
addProfile(name: string, image: File): void {
const profileData = new FormData();
profileData.append("name", name);
profileData.append("image", image, name);
this.http
.post<{ profile: Profile }>(this.url, profileData)
.subscribe((profileData) => {
const profile: Profile = {
_id: profileData.profile._id,
name: name,
imagePath: profileData.profile.imagePath,
};
this.profiles.push(profile);
this.profiles$.next(this.profiles);
});
}
}
Profile.ts
export interface Profile {
_id: string;
name: string;
imagePath: string;
}
推荐文章
- 运行单个测试文件
- “declare”在“export declare class Actions”中做什么?
- NG6002:出现在NgModule中。导入AppModule类，但不能解析为NgModule类
- 向Angular HttpClient添加一个HTTP头并不会发送这个头，为什么?
- 不能绑定到'ngForOf'，因为它不是'tr'的已知属性(最终版本)
- Angular中的全局事件
- Angular和Typescript:不能找到名字——错误:不能找到名字
- HttpModule和HttpClientModule的区别
- 禁用响应式输入字段
- 'this'隐式具有类型'any'，因为它没有类型注释
- 带有用户单击所选组件的动态选项卡
- 在TypeScript中声明抽象方法
- 如何强制tsc忽略node_modules文件夹?
- TypeScript for…的索引/键?
- 如何在Typescript中获得一个变量类型?
