how to just set one observer for a room query

Question

I'm using the room for storing some data in my local database which are fetched from the server-side. these data will show in a recyclerView, also there is a searchView that allows the user to search for some specific data.

now, I was wondering that is there any way I apply two of these features in one way? I used this query to do that but it seems the observer won't trigger just for a change in the function's parameters:

in the other word, my question is:

Imagin I called this query like this:

database.searchFor(null,true).observe(this,observer{
....
})

how can I trigger the above observer after calling the query with another parameter like this:

database.searchFor("Alex",false)

should I change the structure and the way that I do that?

Answer 1

Consider using another LiveData and Transformation's switchMap.

Let's say you have ViewModel where you can declare 2 Livedata - first for parameters (keyword & all), and second - for db observing:

val params = MutableLiveData<Pair<String?, Boolean>>(Pair(null, true)) // <-- default parameters

val searchResults = Transformations.switchMap(params) 
    { 
       params -> database.searchFor(params.first, params.second) // <-- updates with parameters' changes
    }

In your Activity/Fragment you set parameters' values and observe results:

viewModel.searchResults.observe(this, Observer{
   ....
})

viewModel.params.value = Pair("Alex", false) // <-- to search results