我有NestJS应用程序，可与YoutubeAPI交互并从中加载视频。一种特定的方法很重要，它loadVideos来自下面。它本身具有多个异步方法，videoIdMap一旦一切完成，我需要使用属性
private loadVideos(
playListId: string,
channel: Channel,
nextPageToken: string,
stopLoadingOnVideoId: string,
) {
const baseUrl = YoutubeService.VIDEO_URL_SNIPPET_BY_ID + playListId;
const response = this.httpService
.get(nextPageToken ? baseUrl + '&pageToken=' + nextPageToken : baseUrl)
.pipe(map((response) => response.data));
response.subscribe((data) => {
data.items.forEach((item) => {
if (stopLoadingOnVideoId && item.snippet.resourceId.videoId === stopLoadingOnVideoId) {
return;
}
this.prepareVideoEntity(item.snippet, channel).then((partialVideo) =>
this.videoService.create(partialVideo).then((video) => {
this.videoIdMap[video.youtubeId] = video.id;
}),
);
});
if (data.nextPageToken) {
this.loadVideos(
playListId,
channel,
data.nextPageToken,
stopLoadingOnVideoId,
);
}
});
}
对我来说，理想的解决方案是以loadVideos某种方式进行异步处理，以便以后执行：
public methodWhichCallLoadVideos(): void {
await loadVideos(playListId, channel, null, stopLoadingOnVideoId)
// My code which have to be executed right after videos are loaded
}
我尝试过的每个解决方案最终this.videoIdMap都是空对象或编译问题，因此任何想法都值得欢迎。
您可以切换到Promise而不是Observables，从而将方法转换为异步方法，只要data具有a ，该方法便会重复出现nextPageToken：
private async loadVideos(
playListId: string,
channel: Channel,
nextPageToken: string,
stopLoadingOnVideoId: string,
) {
const baseUrl = YoutubeService.VIDEO_URL_SNIPPET_BY_ID + playListId;
const response = await this.httpService
.get(nextPageToken ? url + '&pageToken=' + nextPageToken : url).toPromise();
const { data } = response;
for (const item of data.items) {
if (stopLoadingOnVideoId && item.snippet.resourceId.videoId === stopLoadingOnVideoId) {
continue;
}
const partialVideo = await this.prepareVideoEntity(item.snippet, channel);
const video = await this.videoService.create(partialVideo)
this.videoIdMap[video.youtubeId] = video.id;
}
if (data.nextPageToken) {
await this.loadVideos(
playListId,
channel,
data.nextPageToken,
stopLoadingOnVideoId,
);
}
}
在您的呼叫者中，您只需等待loadVideos(...)：
private async initVideoIdMap(...) {
await this.loadVideos(...);
// this.videoIdMap should be correctly populated at this point
}
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