仅从 Flutter 中的完整日期中提取年份

Question

这是我的 json 数据结构：

[
   [
    {
     "nos": 0,
     "name": "A S MUSIC AND DANCE A CULTURAL ORGANIZATION",
     "unique_id": "AN/2020/0259067",
      "reg_details": [
                       {
                        "registered_with": "Registrar of Societies"
                        },
                        {
                        "type_of_ngo": "Registered Societies (Non-Government)"
                         },
                            {
                            "registration_no": "1534"
                              },
                           {
                              "copy_of_registration_certificate": "Available"
                           },
                            {
                              "copy_of_pan_card": "Available"
                             },                    
                              {
                               "date_of_registration": "25-05-2016"
                              }
],

我只想从日期键值与 年份 比较，即"date_of_registration": "25-05-2016"。

从小部件中获取值的我的按钮是：

    RoundedButton(
                      text: "Next",
                      press: () async {
                        debugPrint(_currentValue.toString());
                        _NgoDetail(ngo,_currentValue.toString());
                       //Where _currentValue is actually the year I'm getting 
                        //from a spinner widget

                      },
                    ),

与这些值进行比较的函数是：

  Future<bool>  _NgoDetail(String name,String year) async { //Only Year as a 
                                                //  parameter and not whole date
    String jsonString = await _loadANgoAsset();
    final jsonResponse = json.decode(jsonString);
    int k=-2;
   
    List<dynamic> allNamesOfNGO=jsonResponse[0];


    allNamesOfNGO.takeWhile((value) => value != name).forEach((allNamesOfNGO){
      (allNamesOfNGO as Map<String, dynamic>).forEach((key, value) {
       ++k;
        if(key=='name' && value == name){
           if(key=='date_of_registeration' && value == year) //Here value is 
                                                          //complete date, I want 
                                                          //it to be year only
           {
            Navigator.push(context,MaterialPageRoute(builder: (context)=> R3(jsonIndexOfNGO:k)));
           }                          
        }
        else{
          Fluttertoast.showToast(
              msg: "Your given details doesn't match. Please try again",
              toastLength: Toast.LENGTH_SHORT,
              gravity: ToastGravity.CENTER,
              timeInSecForIosWeb: 3,
              backgroundColor: Colors.red,
              textColor: Colors.white,
              fontSize: 16.0);
        }

      } );
    });

  



  }

我应该先在上面的函数中做什么？从 json 中检索所有日期值并将其格式从 25-02-2015 转换为 2015 或执行其他方法？

Answer 1

试试这个

    List<dynamic> allNamesOfNGO=jsonResponse[0];


    allNamesOfNGO.takeWhile((value) => value != name).forEach((allNamesOfNGO){
      (allNamesOfNGO as Map<String, dynamic>).forEach((key, value) {
       ++k;
        if(key=='name' && value == name){
           if(key=='date_of_registeration' && value.substring(6) == year) //Here value is 
                                                          //complete date, I want 
                                                          //it to be year only
           {
            Navigator.push(context,MaterialPageRoute(builder: (context)=> R3(jsonIndexOfNGO:k)));
           }                          
        }
        else{
          Fluttertoast.showToast(
              msg: "Your given details doesn't match. Please try again",
              toastLength: Toast.LENGTH_SHORT,
              gravity: ToastGravity.CENTER,
              timeInSecForIosWeb: 3,
              backgroundColor: Colors.red,
              textColor: Colors.white,
              fontSize: 16.0);
        }

      }