如何使用 .where(GreaterThan, and LessThan) 条件从 firestore 获取数据。 - 颤振

Question

I'm trying to fetch data from firestore using the .where() condition.

 Query adsRef = FirebaseFirestore.instance
    .collection('All ads')        
    .where('adPrice',
        isGreaterThanOrEqualTo: '2000') 
    .where('adPrice',
        isLessThanOrEqualTo: '115000') 
    .limit(adsPerPage);
QuerySnapshot querySnapshot = await adsRef.get();

When using only one condition (eg: .where('adPrice',isGreaterThanOrEqualTo: '2000') ) works but dosen't fetch all documents[Just fetching random documents].
And when using both condtions it retruns null even though the DB has matching data.

Is there any other way to fetch data from firestore within two numbers? (in between 2000 to 115000)

Answer 1

Two inequality conditions are not valid in one firestore query. wrap you block of code in try catch and you will see the error.

Alternatively you can query both of your conditions separately and then merge the results like this:

void getAds() async {
    List<Future<QuerySnapshot>> futures = [];
    var firstQuery = FirebaseFirestore.instance
.collection('All ads')
        .where('adPrice', isGreaterThanOrEqualTo: '2000')
        .getDocuments();
var secondQuery = FirebaseFirestore.instance
.collection('All ads')
        .where('adPrice', isLessThanOrEqualTo: '115000')
        .getDocuments();

    futures.add(firstQuery);
    futures.add(secondQuery);

    List<QuerySnapshot> results = await Future.wait(futures);
    results.forEach((res) {
      res.documents.forEach((docResults) {
        print(docResults.data);
      });
    });
  }

Please do try this and let me know if it works for you. Thanks