在c＃中设置class属性

Question

我有这个结构：

public class StudentNew
{
    public int StudentId { get; set; }
   ...
}

public class RootObjectNew
{
    public List<StudentNew> StudentsNew { get; set; }
    public int test { get; set; }
}

我想将属性设置为StudentsNew。

RootObjectNew RootObjectNewObject = new RootObjectNew();
RootObject obj = JsonConvert.DeserializeObject<RootObject>(Out);
int i = -1;
foreach (var stu in obj.Students)
{   
    i++;
    RootObjectNewObject.StudentsNew[i].StudentId = stu.Id;
    RootObjectNewObject.test = 123;
}

但得到错误：

2018-03-03T09:18:55.628 [Info] Compilation succeeded.
2018-03-03T09:18:56.971 [Info] C#************************
2018-03-03T09:18:57.386 [Error] Exception while executing function: Functions.fGetStudentBySkudId. Microsoft.Azure.WebJobs.Script: One or
more errors occurred. f-fGetStudentBySkudId__-2136340708: Object
reference not set to an instance of an object.

如果我评论

RootObjectNewObject.StudentsNew[i].StudentId = stu.Id;

我得到状态= 200 我做错了什么???

Answer 1

您必须在RootObjectNewObject中创建StudentNew实例：

RootObjectNew RootObjectNewObject = new RootObjectNew();
RootObjectNewObject.StudentsNew = new List<StudentNew>();
RootObject obj = JsonConvert.DeserializeObject<RootObject>(Out);
foreach (var stu in obj.Students)
{   
    var st = new StudentNew{
      StudentId=Stu.Id,
      ...
    };
    RootObjectNewObject.StudentsNew.Add(st);

}