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任何帮助都会很有用。我正在使用 StreamBuilder 将项目加载到页面，第一次打开页面时，产品会出现，但在导航到另一个页面并导航回同一页面后，什么都没有出现。这是我的代码： UI 屏幕：

Widget _buildInventoryPage() {
        return StreamBuilder<List<Inventory>>(
          stream: _inventoryStream,
          builder: (BuildContext context, AsyncSnapshot<List<Inventory>> snapshot) {
            if (snapshot.hasError) return Message();
            if (snapshot.connectionState == ConnectionState.waiting)
              return Loading();
            if (!_onSortInventory) {
              _filteredInventories = [];
              String searchQuery =
                  _inventoryQueryController.text.trim().toLowerCase();
              for (Inventory inventory in snapshot.data)
                if (_filterInventory(inventory, searchQuery))
                  _filteredInventories.add(inventory);
    
              _inventoryTableData = DataTableDataSource(
                currentRow: _inventoryRow,
                data: _filteredInventories,
              );
            }
    
            _onSortInventory = false;
            return Container(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.center,
                children: [
                  _inventorySearchBar(),
                  if (getIt<Data>().isAdmin()) _inventorySummary(),
                  _inventoryTable(),
                ],
              ),
            );
          },
        );
      }

数据：

class InventoryData {
  Uuid uuid = Uuid();

  CollectionReference collection([String companyId]) => Firestore.instance
      .collection('company/${companyId ?? getIt<Data>().cid}/inventory');
  QueryReference query([String companyId]) =>
      collection(companyId).orderBy('name');

  Future<List<Document>> queryQS([String companyId]) async =>
      await query(companyId).get();
  Future<List<Inventory>> queryDocuments([String companyId]) async =>
      queryQS(companyId).then((value) =>
          value.map((e) => Inventory.fromJson(e.map..['id'] = e.id)).toList());
  Stream<List<Inventory>> snapshots([String companyId]) =>
      collection(companyId).stream.map((e) =>
          e.map((f) => Inventory.fromJson(f.map..['id'] = f.id)).toList());

  // await queryQS().then((value) =>
  //     value.map((e) => Inventory.fromJson(e.map..['id'] = e.id)).toList());

  DocumentReference reference(String id, [String companyId]) =>
      collection(companyId).document(id);
  Stream<Inventory> snapshot(String id) =>
      reference(id).stream.map((e) => Inventory.fromJson(e.map..['id'] = e.id));
  Future<Inventory> document(String id, [String companyId]) async =>
      await reference(id, companyId)
          .get()
          .then((e) => Inventory.fromJson(e.map..['id'] = e.id));
  Future<Inventory> inventory(String id, [String companyId]) async =>
      (await document(id, companyId));

  String add(Inventory inventory) {
    String docId = inventory.id ?? getDocId();
    reference(docId).set(inventory.toJson());
    return docId;
  }

  void update(String id, Inventory inventory) =>
      reference(id).update(inventory.toJson());
  void delete(String id) async {
    DocumentReference ref = reference(id);
    List<Batch> batchQuery = await BatchData().queryDocuments(ref);

    for (Batch doc in batchQuery) await reference(doc.id).delete();

    ref.delete();
  }

  Future<Inventory> getBarcode(String barcode) async {
    List<Document> query =
        await collection().where('barcode', isEqualTo: barcode).limit(1).get();
    if (query.length == 0) return null;
    return Inventory.fromJson(query.first.map);
  }

  String getDocId() => uuid.v1();
}

欢迎所有相关答案，我们将不胜感激。

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