AngularFire2 Complex Query

问题

I need to query a Firebase list based on two keys and values. For example:

books
   -gdhagd342363
        status:'Active'
        authers
            -yruywert676:'john markos'
            -eiuqwbj8200:'mark solo'
   -jdfhs8797429
        status:'Active'
        authers
            -yruywert676:'john markos'

So I want to find how many books are (status=='Active') AND (the key of the authers child == -yruywert676).

How to implement such query ?

来源：https://stackoverflow.com/questions/42260757/angularfire2-complex-query