How to query data from Firestore with dynamic input -React-native

Question

I am new to react native firebase firestore. I am designing an app where the functionality is that the user should be able to search for a registered user on any of the three criteria:

-by Name

-by Expertise

-by Location

If the user explicitly types in these fields, my code will retrieve the filtered result from firestore

Code in react native to retrieve from firestore:

var fbdbStartRef= firebase.firestore().db.collection("users");
    var queryResult = routeRef
.where(("Name", "==", NameInput)
.where("Expertise", "==", ExpertiseInput)
.where("Location","==" , LocationInput))
.get().then(function(snapshot){/* ... */}

Scenario: If the user did not type in any search criteria in the UI for any one field, say "Location" , in that scenario I dont want to set the filter for that criteria from firestore. That means , the expected code should be:

componentDidMount() {

const fbdbStartRef=firebase.firestore().collection("users");
const nameFilter=NamesearchInput ? (fbdbStartRef.where("firstName","==",NamesearchInput)):fbdbStartRef;
const expertiseFilter= ExpertiseSearchInput ? (nameFilter.where("Expertise","==",ExpertiseSearchInput)):nameFilter;
const locationFilter=LocationSearchInput ? (expertiseFilter.where( "Location","==",LocationSearchInput)): expertiseFilter;

console.log("location filter", locationFilter)
   locationFilter.get().then((querySnapshot) => {
      const mentorlistLastnameFromDB = [];
      querySnapshot.forEach((doc) => {
        mentorlistLastnameFromDB.push({
          first: doc.data().firstName,
          last: doc.data().lastName,
          location: doc.data().Location,
          expertise: doc.data().Expertise,
          profilepic: doc.data().profilePicUrl,
          userID:doc.data().userID,
        });
        console.log("mentor list from db 0", mentorlistLastnameFromDB)
      });
      this.setState({
        mentorListAll: mentorlistLastnameFromDB,
      });
      console.log("mentor list", mentorlistLastnameFromDB)
      });
}

render() {
    return (
            <FlatList
              data={this.state.mentorListAll}

              renderItem={
                ({ item, index }) => {
                  return (

                    <Text { documentid:item.userID}/ >
/>
                  



 

Question: However the query did not get the result. Per the console.log the query result array is empty Please refer the attached screen shot for the VSS code . Can you please review and suggest what am I doing wrong here

The below mentioned threads did not answer my query. Hence opening a new question How to query data from Firestore with dynamic input [duplicate] Can you create dynamic firebase queries? How to build a Firestore query chain based on a dynamic response from a promise