c# list in list and incorrect instance of an object

Question

I have such structure

public class Agent
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}
public class Student
{
    public int Id { get; set; }
    public List<Agent> Agents { get; set; }
}
public class RootObject
{
    public List<Student> Students { get; set; }

and this code

RootObject obj = JsonConvert.DeserializeObject<RootObject>(Out);
foreach (Student stu in obj.Students)
{   
    ...
    foreach (Agent Agent in stu.Agents)
    {
        ...
    }
}

foreach (Agent Agent in stu.Agents)

get error

Object reference not set to an instance of an object.

Tell me how I should correctly declare objects

First, you need to check if JSON was deserialized correctly. — FaizanHussainRabbani, Mar 04 '18 at 09:18
What is the value of `Out`? Probably it contains no agents. Have you even tried to debug? — Peter Bons, Mar 04 '18 at 09:19
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Peter Bons, Mar 04 '18 at 09:20
FaizanRabbani, thanks, you are right, one of the cycles did not return agents — Ирина Скорикова, Mar 04 '18 at 09:35

score 0 · Answer 1 · answered Mar 05 '18 at 08:47

You can add Agents list initialization in Student class default constructor. It will help you to handle absence of Agents in your JSON.

Try this.

public class Student
{
    public int Id { get; set; }
    public List<Agent> Agents { get; set; }

    public Student()
    {
        Agents = new List<Agent>();
    }
}

c# list in list and incorrect instance of an object

1 Answers1