Flutter FireRestore：如何从特定实际领域获取数据

我想从Collection "Kinder"中获得Field的"子元素". 但只有实际的一个，而不是整个系列.

StreamBuilder<QuerySnapshot>(
        stream: FirebaseFirestore.instance
            .collection("Users")
            .doc(currentUser?.email)
            .collection("Kinder")
            .doc(widget.docID)
   
            
            
            .snapshots(),
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          if (snapshot.hasError) {
            return Text('Something went wrong');
          }

          if (snapshot.connectionState == ConnectionState.waiting) {
            return Text("Loading");
          }

          return ListView(
            children: snapshot.data!.docs.map((DocumentSnapshot document) {
              Map<String, dynamic> data = document.data()! as Map<String, dynamic>;
              return ListTile(
                title: Text(data['child']),
              );
            }).toList(),
          );
        },
      ),

谢谢！

使用此代码，我获得了正确的集合，但所有"子"字段. 当我添加".Doc(Widget.docID)"时，我需要添加另一个".collection(.)"?