Filter rxjava observable using other observable

I am using rxandroid 2.0.1 and rxjava 2.0.6

I have two observable: one returns may < MyObject > based on some string (ID). When returning an optional object, I must call the second to obtain the MyObject instance and return single < Boolean > if the object meets some conditions. Then I can use the object instance to do some further operations

My current implementation is as follows:

objectDAO.getById(objectId)
    .subscribe(
        myObject -> checkCondition(myObject),
        throwable -> /* Fallback */,
        () -> /* Fallback */
    );

private void checkCondition(final MyObject myObject) {
  otherDAO.checkCondition(myObject)
    .subscribe(
        isTrue -> {
          if (isTrue) {
            // yay! Now I can do what I need with myObject instance
          } else {
            /* Fallback */
          }
        },
        throwable -> /* Fallback */
    );
}

Now I want to know how to simplify my code. My idea:

>Try using zip – I can't, because the second observable can't subscribe until the first one returns MyObject > try using filter – now the problem is that I need to call the second observable with blocking get. It works, but it looks like code smell:

objectDAO.getById(objectId)
  .filter(myObject ->
    otherDAO.checkCondition(myObject).blockingGet()
  )
  .subscribe(
      myObject -> checkCondition(myObject),
      throwable -> /* Fallback */,
      () -> /* Fallback */
  );

>Try using flatmap - the second observable returns a Boolean value, and I need to return the original object. Therefore, I need to write a code fragment using blockingget and return the original object or maybe. Empty()

How can any suggestion be made in such a way that the code is "clean" (it's smaller and still knows what's going on inside)?

resolvent:

One thing you can do:

objectDAO.getById(objectId)
    .flatMapSingle(myObject -> otherDAO
        .checkCondition(myObject)
        .map(isTrue -> Pair.create(myObject, isTrue))
    )

Then you have an observable < < pair < < MyObject, Boolean > > and can continue as needed: Subscribe directly and check Boolean values, filter by Boolean values, etc