[英]RxJava2 passing data through flatMap on a Single
In rxjava 1 there Observable had this flatmap method 在rxjava 1中,Observable具有此flatmap方法
public final Observable flatMap(Func1 collectionSelector, Func2 resultSelector) 公共最终的Observable flatMap(Func1 collectionSelector,Func2 resultSelector)
That allowed you to pass/combine the initial result to the flatmap subscriber. 这使您可以将初始结果传递/组合到平面图订户。
How can I achieve the same result with RxJava2? 如何使用RxJava2获得相同的结果?
I have a Single that emits A
, I need to get B
based on A
and then use both A
and B
to perform an action. 我有一个发出A
的Single,我需要根据A
获取B
,然后同时使用A
和B
来执行操作。
You have the same method on RxJava2, both on Observable and Flowable , 你有RxJava2同样的方法,无论是在可观测和可流动 ,
but, in both RxJava1 and 2, there is no such operator for Single
, you can transform Single
to Observable
and then apply this operators. 但是,在RxJava1和2中,都没有用于Single
此类运算符,您可以将Single
转换为Observable
,然后应用此运算符。
Have you tried CombineLatest ( http://reactivex.io/documentation/operators/combinelatest.html ) 您是否尝试过CombineLatest( http://reactivex.io/documentation/operators/combinelatest.html )
Basically you can emit A and B and then return another object based on the function result: 基本上,您可以发出A和B,然后根据函数结果返回另一个对象:
RXJava1 RXJava1
Observable
.combineLatest([Add here your A observable],
[Add here your B observable],
new Func2<A, B, Result>() {
@Override
public Result call(A a, B b) {
//Do your stuff here combining both results and return the result expected
}
})
RXJava2 RXJava2
Observable
.combineLatest([Add here your A observable],
[Add here your B observable],
new BiFunction<A, B, Result>() {
@Override
public Result apply(A a, B b) throws Exception {
//Do your stuff here combining both results and return the result expected
}
})
The answer by Yosriz is correct but to add a code example: Yosriz的答案是正确的,但要添加一个代码示例:
Assuming the following: 假设以下内容:
class A {}
class B {}
class AB {
private final A a;
private final B b;
AB(A a, B b) {
this.a = a;
this.b = b;
}
}
interface AbRepository {
Single<A> getA();
Single<B> getB(A a);
}
Note that the method getB
requires an A
as a parameter. 请注意,方法getB
需要A
作为参数。
Then you can do: 然后,您可以执行以下操作:
abRepository.getA()
.toObservable()
.flatMap(new Function<A, ObservableSource<B>>() {
@Override
public ObservableSource<B> apply(A a) throws Exception {
return abRepository.getB(a)
.toObservable();
}
}, new BiFunction<A, B, AB>() {
@Override
public AB apply(A a, B b) throws Exception {
return new AB(a, b);
}
})
.firstOrError();
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