如何在flutter中添加多个具有firebase下拉值的streambuilder？

Question

I have 3 dropdown that has lists from firebase. The flowchart of my program is when I choose the address, so the username and password are automatically selected according to the address that has been selected. This is my code:

StreamBuilder 1

StreamBuilder<QuerySnapshot>(
   stream: FirebaseFirestore.instance.collection('servers').snapshots(includeMetadataChanges: true),
   builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
      if (snapshot.hasError) {
         return Text('Something went wrong');
      }
      if (snapshot.connectionState == ConnectionState.waiting) {
         return Text("Loading");
      }
      return Container(
         child: DropdownSearch<String>(
            items: snapshot.data!.docs.map((DocumentSnapshot document) {
               Map<String, dynamic> data = document.data()! as Map<String, dynamic>;
               return data["address"];
            })
            .toList()
            .cast<String>(),
         onChanged: print,
         ),
      );
   },
),

StreamBuilder 2

StreamBuilder<QuerySnapshot>(
   stream: FirebaseFirestore.instance.collection('servers').snapshots(includeMetadataChanges: true),
   builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
      if (snapshot.hasError) {
         return Text('Something went wrong');
      }
      if (snapshot.connectionState == ConnectionState.waiting) {
         return Text("Loading");
      }
      return Container(
         child: DropdownSearch<String>(
            items: snapshot.data!.docs.map((DocumentSnapshot document) {
               Map<String, dynamic> data = document.data()! as Map<String, dynamic>;
               return data["username"];
            })
            .toList()
            .cast<String>(),
         onChanged: print,
         ),
      );
   },
),

StreamBuilder 3

StreamBuilder<QuerySnapshot>(
   stream: FirebaseFirestore.instance.collection('servers').snapshots(includeMetadataChanges: true),
   builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
      if (snapshot.hasError) {
         return Text('Something went wrong');
      }
      if (snapshot.connectionState == ConnectionState.waiting) {
         return Text("Loading");
      }
      return Container(
         child: DropdownSearch<String>(
            items: snapshot.data!.docs.map((DocumentSnapshot document) {
               Map<String, dynamic> data = document.data()! as Map<String, dynamic>;
               return data["password"];
            })
            .toList()
            .cast<String>(),
         onChanged: print,
         ),
      );
   },
),

And this is my firebase database:

I've tried to write those code inside children: <Widget>[] but the data can't showed in my app.

Thank you in advance for any help.

Answer 1

Dropdowns are usually used as static data so if you are keeping that data in firebase. It would be better to fetch this data in a list in initState method and then use in the StreamBuilder instead of fetching it in StreamBuilder