AlertBox没有显示颤动

Question

我有带有图像和一些详细信息的Listview，如果没有数据，它应该返回一个带有消息的警报框，但是当我尝试该警报框时，我正在为此使用rflutter

如果没有数据，这就是我要得到的内容

{
  "status": true,
  "doc": []
}

如果json返回而没有数据，则应弹出警报框

图像列表代码

Future<String> getImageList(String area_id) async {

    ProgressDialog dialog = CustomDialogs().showLoadingProgressDialog(context);

         var response = await http.post(Urls.ImageList,
              headers: {
                "Content-Type": "application/json",
                "Authorization": "Bearer $token",
              },
              body: json.encode({
                "branchId": branchid,
                "sectionId": section_id,
                "reportTimeType": "1",
                "areaId": area_id,
              }));

          if (response.statusCode == 200) {

            dialog.dismissProgressDialog(context);

            try {
              var resp = response.body;
              print(resp);
              if(resp != null)
                {
                  Map<String, dynamic> value = json.decode(resp);
                  var report = value['doc'];

                  for (int i = 0; i < report.length; i++) {
                    var data = report[i];
                    var areaName = data["Area_Id"]["Area_Name"];
                    var branchName = data["Branch_Id"]["name"];
                    Imagelist.add(ImageModel.fromJson(data, areaName, branchName));
                  }

                  setState(() {
                    array_lenth = Imagelist.length;
                  });
                }
              else
                {
                  Alert(
                    context: context,
                    type: AlertType.error,
                    title: "No Data",
                    desc: "No Avilable Data Found",
                    buttons: [
                      DialogButton(
                        child: Text(
                          "COOL",
                          style: TextStyle(color: Colors.white, fontSize: 20),
                        ),
                        onPressed: () => Navigator.pop(context),
                        width: 120,
                      )
                    ],
                  ).show();
                }

            } catch (e) {
              e.toString();
            }
          }
          else {
            CustomDialogs().showErrorAlert(_scaffoldKey.currentContext, "Try Again....");
          }
      }
  }

Answer 1

您正在检查null，但应检查其长度。

您的条件应如下。

 if(resp.length > 0)