C# elegant way to check if a property's property is null

In C#, say that you want to pull a value off of PropertyC in this example and ObjectA, PropertyA and PropertyB can all be null.

ObjectA.PropertyA.PropertyB.PropertyC

How can I get PropertyC safely with the least amount of code?

Right now I would check:

if(ObjectA != null && ObjectA.PropertyA !=null && ObjectA.PropertyA.PropertyB != null)
{
    // safely pull off the value
    int value = objectA.PropertyA.PropertyB.PropertyC;
}

It would be nice to do something more like this (pseudo-code).

int value = ObjectA.PropertyA.PropertyB ? ObjectA.PropertyA.PropertyB : defaultVal;

Possibly even further collapsed with a null-coalescing operator.

EDIT Originally I said my second example was like js, but I changed it to psuedo-code since it was correctly pointed out that it would not work in js.

Solution 1:

In C# 6 you can use the Null Conditional Operator. So the original test will be:

int? value = objectA?.PropertyA?.PropertyB?.PropertyC;

Solution 2:

Short Extension Method:

public static TResult IfNotNull<TInput, TResult>(this TInput o, Func<TInput, TResult> evaluator)
  where TResult : class where TInput : class
{
  if (o == null) return null;
  return evaluator(o);
}

Using

PropertyC value = ObjectA.IfNotNull(x => x.PropertyA).IfNotNull(x => x.PropertyB).IfNotNull(x => x.PropertyC);

This simple extension method and much more you can find on http://devtalk.net/csharp/chained-null-checks-and-the-maybe-monad/

EDIT:

After using it for moment I think the proper name for this method should be IfNotNull() instead of original With().

Solution 3:

Can you add a method to your class? If not, have you thought about using extension methods? You could create an extension method for your object type called GetPropC().

Example:

public static class MyExtensions
{
    public static int GetPropC(this MyObjectType obj, int defaltValue)
    {
        if (obj != null && obj.PropertyA != null & obj.PropertyA.PropertyB != null)
            return obj.PropertyA.PropertyB.PropertyC;
        return defaltValue;
    }
}

Usage:

int val = ObjectA.GetPropC(0); // will return PropC value, or 0 (defaltValue)

By the way, this assumes you are using .NET 3 or higher.

Solution 4:

The way you're doing it is correct.

You could use a trick like the one described here, using Linq expressions :

int value = ObjectA.NullSafeEval(x => x.PropertyA.PropertyB.PropertyC, 0);

But it's much slower that manually checking each property...