我今天遇到了一个有趣的问题.我正在开发一个我们有文件上传的应用程序,我们想要实现一个进度条.该应用程序使用React / Redux / Redux-Observable编写.我想发送上传进度的动作.这是我为实现它所做的：

withProgress(method, url, body = {}, headers = {}) {
    const progressSubscriber = Subscriber.create();

    return {
        Subscriber: progressSubscriber,
        Request:    this.ajax({ url, method, body, headers, progressSubscriber }),
    };
}

我有一个类用于制作我的所有ajax请求. this.ajax使用传入的参数调用Observable.ajax.

export const blobStorageUploadEpic = (action$) => {
    return action$.ofType(a.BLOB_STORAGE_UPLOAD)
    .mergeMap(({ payload }) => {
        const { url, valetKey, blobId, blobData, contentType } = payload;

        const { Subscriber, Request } = RxAjax.withProgress('PUT', `${url}?${valetKey}`, blobData, {
            'x-ms-blob-type': 'BlockBlob',
            'Content-Type':   contentType,
        });

        const requestObservable = Request
        .map(() => ({ type: a.BLOB_STORAGE_UPLOAD_SUCCESS, payload: { blobId } }))
        .catch((err) => Observable.of({ type: a.BLOB_STORAGE_UPLOAD_FAILURE, err }));

        return Observable.fromSubscriber(Subscriber)
        .map((e) => ({ percentage: (e.loaded / e.total) * 100 }))
        .map((percentage) => ({ type: a.BLOB_STORAGE_UPLOAD_PROGRESS, payload: { percentage} }))
        .merge(requestObservable);
    });
};

这是我的史诗.我收到了订阅者,我写了一个Observable的自定义静态方法来接收订阅者.然后我将它与Request(这是一个Observable)合并.

Observable.fromSubscriber = function fromSubscriber(externalSubscriber) {
    return Observable.create((subscriber) => {
        externalSubscriber.next =     (val) => subscriber.next(val);
        externalSubscriber.error =    (err) => subscriber.error(err);
        externalSubscriber.complete = () => subscriber.complete();
    });
};

最后,这是我在Observable上编写的自定义静态方法.我写这个有两个原因. 1.作为处理类似问题的其他人的一个例子(我花了很多时间试图在编写自己的代码之前弄清楚如何从订阅者那里创建一个Observable)和2.要问这是否是最好的完成方法这个目标. rxjs很深,我认为现有的方法可以做到这一点,但我找不到它.

解决方法:

这基本上就是Subject的用途,以下内容也应该有效：

export const blobStorageUploadEpic = (action$) => {
    return action$.ofType(a.BLOB_STORAGE_UPLOAD)
    .mergeMap(({ payload }) => {
        const { url, valetKey, blobId, blobData, contentType } = payload;

        const progressSubscriber = new Rx.Subject();
        const request = Rx.Observable.ajax({
            method: 'PUT',
            url: `${url}?${valetKey}`,
            body: blobData,
            headers: {
                'x-ms-blob-type': 'BlockBlob',
                'Content-Type':   contentType,
            },
            progressSubscriber
        });

        const requestObservable = request
            .map(() => ({ type: a.BLOB_STORAGE_UPLOAD_SUCCESS, payload: { blobId } }))
            .catch((err) => Observable.of({ type: a.BLOB_STORAGE_UPLOAD_FAILURE, err }));

        return progressSubscriber
            .map((e) => ({ percentage: (e.loaded / e.total) * 100 }))
            .map((percentage) => ({ type: a.BLOB_STORAGE_UPLOAD_PROGRESS, payload: { percentage} }))
            .merge(requestObservable);
    });
};

这是一个更通用的例子(直播@jsfiddle)：

let data = "";
for (let c = 0; c < 100000; ++c) {
    data += "" + Math.random();
}

const progressSubscriber = new Rx.Subject();
const request = Rx.Observable.ajax({
  method: 'POST',
  url: "/echo/json/",
  body: JSON.stringify({ data }),
  progressSubscriber
});

progressSubscriber
  .merge(request)
  .subscribe(console.log);