You have two tables in Room(Rx), let say A & B. You have to check in table A, if the value returned is valid then check table B and return the result. Else return error to the user. How can this be done using single stream in Rx. Any suggestions?

Not sure I understand the question. Could you

tableASingle.flatMap { tableBSingle }

?

I think there’s a small step in between,

queryTableA.flatMap {
    if (invalid) {
        Single.error(...)
    } else {
        queryTableB
    }
}

If inside the flatMap .. there is no way to avoid this ?

avoid what?

There is an IF check inside the flatMap(). Can we avoid that . That's look ugly to me 😂

well you could map the first single and throw an exception if invalid, but that's worse imo