我无法理解下载URl的过程，有人可以将其分解为我吗？ 所以我在这里有这个上传组件：
import { Component, OnInit } from '@angular/core';
import { AngularFireStorage, AngularFireUploadTask } from
'angularfire2/storage';
import { AngularFirestore } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Observable';
import { tap, filter, switchMap } from 'rxjs/operators';
import { storage } from 'firebase/storage';
@Component({
selector: 'file-upload',
templateUrl: './file-upload.component.html',
styleUrls: ['./file-upload.component.scss']
})
export class FileUploadComponent {
// Main task
task: AngularFireUploadTask;
// Progress monitoring
percentage: Observable<number>;
snapshot: Observable<any>;
// Download URL
downloadURL: Observable<string>;
// State for dropzone CSS toggling
isHovering: boolean;
constructor(private storage: AngularFireStorage, private db: AngularFirestore) { }
toggleHover(event: boolean) {
this.isHovering = event;
}
startUpload(event: FileList) {
// The File object
const file = event.item(0)
// Client-side validation example
if (file.type.split('/')[0] !== 'image') {
console.error('unsupported file type :( ')
return;
}
// The storage path
const path = `test/${new Date().getTime()}_${file.name}`;
// Totally optional metadata
const customMetadata = { app: 'My AngularFire-powered PWA!' };
// The main task
this.task = this.storage.upload(path, file, { customMetadata })
// Progress monitoring
this.percentage = this.task.percentageChanges();
this.snapshot = this.task.snapshotChanges().pipe(
tap(snap => {
console.log(snap)
if (snap.bytesTransferred === snap.totalBytes) {
// Update firestore on completion
this.db.collection('photos').add( { path, size: snap.totalBytes })
}
})
)
// The file's download URL
this.downloadURL = this.task.downloadURL();
console.log(this.downloadURL)
const ref = this.storage.ref(path);
this.task = ref.put(file, {customMetadata});
this.downloadURL = this.task.snapshotChanges().pipe(
filter(snap => snap.state === storage.TaskState.SUCCESS),
switchMap(() => ref.getDownloadURL())
)
console.log(this.downloadURL);
}
// Determines if the upload task is active
isActive(snapshot) {
return snapshot.state === 'running' && snapshot.bytesTransferred < snapshot.totalBytes
}}
我尝试以一种假定的方式来获取下载URL，但是它是空的，我已经看到了完成它的其他方法，但似乎无法正确完成。即使使用snapshot.downloadURL，下载URL始终为null。 以下是 package.json：
{
"name": "storage-app",
"version": "0.0.0",
"license": "MIT",
"scripts": {
"ng": "ng",
"start": "ng serve",
"build": "ng build",
"test": "ng test",
"lint": "ng lint",
"e2e": "ng e2e"
},
"private": true,
"dependencies": {
"@angular/animations": "^6.0.3",
"@angular/common": "^6.0.3",
"@angular/compiler": "^6.0.3",
"@angular/core": "^6.0.3",
"@angular/forms": "^6.0.3",
"@angular/http": "^6.0.3",
"@angular/platform-browser": "^6.0.3",
"@angular/platform-browser-dynamic": "^6.0.3",
"@angular/platform-server": "^6.0.3",
"@angular/router": "^6.0.3",
"angularfire2": "5.0.0-rc.6",
"core-js": "^2.5.4",
"firebase": "4.12.1",
"rxjs": "^6.0.0",
"rxjs-compat": "^6.2.2",
"zone.js": "^0.8.26"
},
"devDependencies": {
"@angular/cli": "^6.0.8",
"@angular/compiler-cli": "^6.0.3",
"@angular/language-service": "^6.0.3",
"@types/jasmine": "~2.5.53",
"@types/jasminewd2": "~2.0.2",
"@types/node": "~6.0.60",
"codelyzer": "^4.0.1",
"jasmine-core": "~2.6.2",
"jasmine-spec-reporter": "~4.1.0",
"karma": "~1.7.0",
"karma-chrome-launcher": "~2.1.1",
"karma-cli": "~1.0.1",
"karma-coverage-istanbul-reporter": "^1.2.1",
"karma-jasmine": "~1.1.0",
"karma-jasmine-html-reporter": "^0.2.2",
"protractor": "~5.1.2",
"ts-node": "~3.2.0",
"tslint": "~5.7.0",
"typescript": "~2.7.2",
"@angular-devkit/build-angular": "~0.6.8"
}
}
预先感谢
答案 0 :(得分：2)
您可以从存储参考中检索下载网址：
loading = false;
uploadFile(event) {
this.loading = true;
const file = event.target.files[0];
// give it a random file name
const path = Math.random().toString(36).substring(7);
const storageRef = this.storage.ref(path);
const task = this.storage.upload(path, file);
return from(task).pipe(
switchMap(() => storageRef.getDownloadURL()),
tap(url => {
// use url here, e.g. assign it to a model
}),
mergeMap(() => {
// e.g. make api call, e.g. save the model
}),
finalize(() => this.loading = false)
).subscribe(() => {
// success
}, error => {
// failure
});
}
我正在使用angularfire 5.0.0-rc.11
答案 1 :(得分：0)
这是一个简单的示例，可帮助您了解操作方法（摘自AngularFire2 GitHub）：
uploadPercent: Observable < number > ;
downloadURL: Observable < string > ;
constructor(
private storage: AngularFireStorage
) {
}
uploadFile(event) {
const file = event.target.files[0];
const filePath = 'files';
const fileRef = this.storage.ref(filePath);
const task = this.storage.upload(filePath, file);
// observe percentage changes
this.uploadPercent = task.percentageChanges();
// get notified when the download URL is available
task.snapshotChanges().pipe(
finalize(() => this.downloadURL = fileRef.getDownloadURL())
)
.subscribe()
}
这是此模板：
<input type="file" (change)="uploadFile($event)" />
<div>{{ uploadPercent | async }}</div>
<a [href]="downloadURL | async">{{ downloadURL | async }}</a>
正在发生的事情：
我们正在处理文件输入的change事件。完成后，我们将上传文件。然后，我们通过调用ref并将其路径传递到文件来在Firebase存储上创建文件引用。这将在以后检索文件下载URL时有所帮助。
此后，我们通过在storage上调用upload并向其传递文件路径和要上传的文件来创建AngularFireUplaodTask。
在此任务上，我们可以通过在上传任务上调用percentageChanges来检查文件的上传百分比。这又是一个Observable，因此我们正在使用async管道监听并在DOM上打印更改。
finalize将在完成上传任务时触发。这样一来，我们便可以通过在之前创建的getDownloadURL上调用fileRef来获取下载URL。
您可以查看此StackBlitz了解更多信息。
答案 2 :(得分：0)
现在在上载的即时结果中不再可以访问下载URL。几个月前，对Firebase客户端SDK进行了此更改。
相反，您必须调用getDownloadURL（或该JavaScript函数的任何Angular绑定）来将URL作为上传完成后的第二个请求。
答案 3 :(得分：0)
Angularfire 提供了这个超级方便的管道，getDownloadURL：
<img [src]="'users/davideast.jpg' | getDownloadURL" />
官方docs。
结束。