CODEWITHSUNDEEP
rx-java2
ShahRukhMlk
ShahRukhMlk

Reputation: 1

Modify each item from Flowable<List<Item>> depending on another Flowable<List<Item2>> in RxJava

I have 3 methods in my Room Database

Flowable<List<Book>> getBooks() {....}
Flowable<List<Author>> getAuthors(int bookId) {....}
Flowable<List<Category>> getCategories(int bookId) {....}

The Book object 

Book {int id; List<Author> authors; List<Category> categories}

I am trying to do something like

Flowable<List<Book>> getBookFullBooks() {
    return getBooks()
    //1. get the list of books from flowable??
    //2. get each book from the list??
    //3. set properties of each book from getAuthors(book.id) and 
    //   getCategories(book.id)
    // Something like:
        .switchMap(book -> _getCategories(book.id).map(categories -> {
            book.categories = categories;
            return book;
        }))
       .switchMap(book -> _getAuthors(book.id).map(authors -> {
           book.authors = authors;
           return book;
       }));// collect the books into a sequentioal Flowable<List<Book>>
}
//4. then return all the books as Flowable<List<Book>>

I have been trying to do so but without any success. How can we do that?

Upvotes: 0

Views: 657

Answers (1)

Tuby
Tuby

Reputation: 3253

I would do something like this

getBooks()
    .flatMapSingle(bookList -> Flowable.fromIterable(bookList)
        .flatMap(book -> getCategories(book.id)
            .map(categories -> {
                   book.setCategories(categories);
                   return book;
            }))
        .flatMap(book -> getAuthors(book.id)
            .map(authors -> {
                   book.setAuthors(authors);
                   return book;
             }))
          .toList())
    .subscribe(bookList -> {
        // done
    });

I think it didn't work on the first time because your Flowable<List<Book>> didn't complete and toList() got stuck. Try to nest the flatMaps, it should work not because Flowable.fromIterable() completes after its done looping.

I created test like this and it works fine https://pastebin.com/Fus4MvXW

Upvotes: 1

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