how we can run multiple queries on Firebase/firestore to get filtered data in flutter?

Question

how we can run multiple queries on Firebase / firestore to get filtered data in flutter or any other possible solution? there is a picture storing dummy data in goal and title and wanna users according to the goals and titles filters .

Answer 1

Where() is a function provided by Firebase to query data

FirebaseFirestore.instance.collection('yourCollectionName').where('field1', isEqual:'value1').where('field2', isEqual: 'value2').get();

you can read more about it in the querying section at https://firebase.flutter.dev/docs/firestore/usage/

Answer 2

By looking at your Firestore database it is clear that you want to filter the documents based on two array fields goals and titles .

Firestore supports the arrayContains filter in the where clause by which you can filter data from an array inside Firestore. So you may think of doing something like this -

var filter1 = 'Hire Employees';
   var filter2 = 'CEO';
   FirebaseFirestore.instance
       .collection('collectionId')
       .where('goals', arrayContains: filter1)
       .where('titles', arrayContains: filter2)
       .get()
       .then((QuerySnapshot docs) => {
             for (var element in docs.docs) {print(element.data())}
           });

But the above will throw an error saying that You cannot use 'array-contains' filters more than once . This is because Firestore has a limitation that you can use at most one array-contains clause per query which is documented here . So it is not possible to do something like the above.

I am not very sure of your use case, but as a workaround, you can restructure the database structure by making any one of the array field to a map, something like the following -

By making the structure like the above you can use multiple where clauses with one arrayContains filter and one isEqualTo filter which will look something like this -

   var filter1 = 'Hire Employees';
   var filter2 = 'CEO';
   FirebaseFirestore.instance
       .collection('collectionId')
       .where('goals.$filter1', isEqualTo: true)
       .where('titles', arrayContains: filter2)
       .get()
       .then((QuerySnapshot docs) => {
             for (var element in docs.docs) {print(element.data())}
           });

As the idea of allowing multiple arrayContains filters is currently not supported, but could be valid, I would recommend you file a feature request .