我的钱包在更新 firebase 后拒绝显示余额

Question

在 Future builder 中更新此行后

Container(
  child: FutureBuilder<DocumentSnapshot>(
    future: FirebaseFirestore.instance
        .collection("users")
        .doc(RitechApp.sharedPreferences
        .getString(RitechApp.userUID))
        .get(),
    builder: (c, snapshot) {
      if (!snapshot.hasData)
        return Center(
          child: CircularProgressIndicator(
            valueColor:
            new AlwaysStoppedAnimation<Color>(
                kPrimaryColor),
          ),
        );
      else {
        return Text(
          "KES" +
              snapshot..data.data["Wallet"]
                  .toString() ??
              0.toString(),
          style: TextStyle(
              fontSize: 25,
              fontFamily: "Muli",
              color: Colors.white),
        );
      }
    },
  ),
),

在 firebase 数据库更新以及遵守 null 安全规则之后，我无法检索钱包余额或更新每笔交易。 这是代码：

Container(
  child: FutureBuilder<DocumentSnapshot>(
    future: FirebaseFirestore.instance
        .collection("users")
        .doc(RitechApp.sharedPreferences
            .getString(RitechApp.userUID))
        .get(),
    builder: (c, snapshot) {
      if (!snapshot.hasData)
        return Center(
          child: CircularProgressIndicator(
            valueColor:
                new AlwaysStoppedAnimation<Color>(kPrimaryColor),
          ),
        );
      else {
        return Text(
          "KES" + snapshot.data!["Wallet"].toString() ??
              0.toString(),
          style: TextStyle(
              fontSize: 25,
              fontFamily: "Muli",
              color: Colors.white),
        );
      }
    },
  ),
),

我无法检索钱包余额或更新每笔交易。 这是代码。

Answer 1

为未来创建一个 state 变量

  late final myFuture = FirebaseFirestore.instance
      .collection("users")
      .doc(RitechApp.sharedPreferences.getString(RitechApp.userUID))
      .get();

并像这样使用 FutureBuiler，如果出现故障，您将收到错误消息

child: FutureBuilder<DocumentSnapshot?>(
  future: myFuture,
  builder: (c, snapshot) {
    if (snapshot.hasData) {
     // 
      return Text(
        // "KES ${snapshot.data?["Wallet"] ?? 0} ",
         "KES ${snapshot.data?.get("Wallet") ?? 0}",
        style: TextStyle(
            fontSize: 25, fontFamily: "Muli", color: Colors.white),
      );
    } else if (snapshot.hasError) {
      return Text(" ${snapshot.error}");
    } else {
      return Center(
        child: CircularProgressIndicator(
          valueColor: new AlwaysStoppedAnimation<Color>(Colors.red),
        ),
      );
    }
  },
),