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[英]How to keep receiving values if an inner Observable fails in a stream of Observable of Observables?
[英]How to map observable object with inner observables?
如何使用內部可觀察對象 map 可觀察 object?
以下是我如何獲取項目的詳細信息。 我想 map 收到的 object 具有未包裝的屬性。
this.fetchData.getItemData().pipe(
mergeMap((item: any) => {
return {
...item,
images: item.images.map(id => this.http.get(baseUrl + link)) -->> I want to unwrap here. (it is an observable; that's why!)
}
})
)
在這里,我將作為數組的內部屬性圖像映射到可觀察的數組!
這是我嘗試過的:
this.fetchData.getItemData().pipe(
forkJoin((item: any) => {
return {
...item,
images: item.images.map(id => this.http.get(baseUrl + link))
}
})
)
this.fetchData.getItemData().pipe(
mergeMap((item: any) => {
return {
...item,
images: item.images.map((id) =>
flatMap(() => this.http.get(baseUrl + link))
),
};
})
)
試試這個,設置itemResponse
的外部值,然后稍后使用它。
import { mergeMap, map } from 'rxjs/operators';
....
let itemResponse: any;
this.fetchData.getItemData().pipe(
mergeMap((item: any) => {
// assign itemResponse to item be used later
itemResponse = item;
// switch to all images
return forkJoin(...item.images.map((id) => this.http.get(baseUrl + link)));
}),
// spread itemResponse and assign images property to images value and return the object
map(images => ({ ...itemResponse, images })),
);
這是聚合 RxJS 請求的示例。
由於只有 2 個級別的請求,您可以簡單地嵌套:
this.fetchData.getItemData().pipe(
mergeMap((item: any) => forkJoin(item.images.map(id => this.http.get(baseUrl + link))).pipe(
// At this point all previous results are in scope so format the result as required
map(images => ({...item, images})
)
);
如果您不喜歡嵌套,或者想要更通用的解決方案,您可以使用實用運算符concatJoin (請注意,我參與了它的實現):
// fetch all the data, with all results aggregated into an object
concatJoin(
{item: this.fetchData.getItemData()},
{images: ({item:any}) => forkJoin(item.images.map(id => this.http.get(baseUrl + link)))}
).pipe(
// convert it into the format you want
map(({item:any, images}) => ({...item, images}))
);
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