Angular Error: Type 'Observable<number | undefined>' is not assignable to type 'Observable<number>'

Question

我正在 Angular 中创建一个将文件上传到 firebase 存储的服务，但是最新版本的 typescript 要求声明更具体，所以它不允许我有一个类型号的变量初始化为未定义，我在尝试获取文件上传百分比时收到以下错误：

Type 'Observable<number | undefined>' is not assignable to type 'Observable'. Type 'number | undefined' is not assignable to type 'number'. Type 'undefined' is not assignable to type 'number'.ts(2322)**

这是我的文件项class:

export class FileItem {
    public name: string;
    public uploading: boolean = false;
    public uploadPercent?: Observable<number>;
    public downloadURL?: Observable<string>;

    constructor(public file: File = file) {
        this.name = file.name;
    }

这是我不知道如何修改的代码行：

item.uploadPercent = task.percentageChanges()

完整的函数为：

uploadFiles(folderPath: string, files: FileItem[]) {
    for (const item of files) {
      item.uploading = true;

      const filePath = this.generateFileName(folderPath, item.name);
      const fileRef = this.storage.ref(filePath);
      const task = this.storage.upload(filePath, item.file);

      item.uploadPercent = task.percentageChanges()
      task
        .snapshotChanges()
        .pipe(
          finalize(() => {
            item.downloadURL = fileRef.getDownloadURL();
            item.uploading = false;
          })
        )
        .subscribe();
    }

.percentageChanges() 方法returns 如下：

percentageChanges(): observable<number | undefined>;

Answer 1

我假设错误来自这一行（如果不是，请添加错误告诉您的确切代码部分（它告诉您数字行）。

那么...它允许你这样声明 uploadPercent?:

public uploadPercent?: Observable<number|undefined>;

如果是这样，我想通过这个小小的改变，您将解决错误。

如果没有，请尝试：

public uploadPercent?: Observable<number|any>;

如果这些解决方案中的 none 有效，请显示失败的确切代码部分，并且当 returns 'Observable<number | undefined>' 强制执行 'Observable<number | undefined>' 时，解决方案将通过更改=27=] 'Observable< number>'

Angular Error: Type 'Observable<number | undefined>' is not assignable to type 'Observable<number>'

Angular Error: Type 'Observable<number | undefined>' is not assignable to type 'Observable<number>'

typescript

firebase-storage

angular