Check if each level of object exists

Question

Lets consider an example model as below.

class student
{
    public int ID { get; set; }
    public string Name { get; set; }
    public school SchoolName { get; set; }
}

class school
{
    public int ID { get; set; }
    public string Name { get; set; }
}

student student1 = new student();

As we all know that we access school name as below.

Console.WriteLine(student1.SchoolName.Name);

If school is not assigned to a student, student1.SchoolName will be null. So the above Console.WriteLine() fails.

I end up writing a if statement for all such elements, which is a pain in the a$$. Do we have an alternate way to handle these cases?

Answer 1

try this:

Console.WriteLine(student1.SchoolName?.Name);

if SchoolName is null, then Name property will not be evaluated.

Answer 2

Unfortunately, we have to do explicit null checking for previous versions to C#

in C# 6.0 we have Null-Conditional operator ?

This operator does exactly what you are looking, if the left side of the operator is null, it cascades a null of the resulting type to the right.

So you could do this.

Console.WriteLine(student1.SchoolName?.Name);

In short, if you replace your . with the null conditional operator ?. it will cascade the null down the line:

Check this Example