angular - RXJS groupBy Observable <对象[]>

Question

我有entries$: Observable<BooksOverviewGroup[]>; :

我想按 groupId 对它们进行分组。我试过这样:

groupBy(books => books.map(book => book.groupId)),
 mergeMap(innerObs => innerObs.skip(1).map(books => books.map(book => book.groupTitle)));

然而，它并没有奏效。在这种情况下如何按 groupId 分组？ (Observable<Object[]>)

Answer 1

你几乎明白了。

尝试在 groupBy() 之前使用 mergeMap() 或 concatMap()。

举个例子:

const people = [
  { name: 'Sue', age: 25 },
  { name: 'Joe', age: 30 },
  { name: 'Frank', age: 25 },
  { name: 'Sarah', age: 35 }
];

of(people) // <- this gets Observable<Object[]>
  .pipe(
    mergeMap(res => res), // <- use concatMap() if you care about the order
    groupBy(person => person.age, p => p.name),
    mergeMap(group => zip(of(group.key), group.pipe(toArray())))
  )
  .subscribe(console.log);

输出:

(2) [25, Array(2)]
(2) [30, Array(1)]
(2) [35, Array(1)]