Checking for null before ToString()

Question

Here\'s the scenario...

if (entry.Properties[\"something\"].Value != null)
  attribs.something = entry.Properties[\"something\"].Value.ToString();
<         


        

Answer 1

Convert.ToString(entry.Properties["something"].Value);

Answer 2

As a variation to RexM's answer:

attribs.something = (entry.Properties["something"].Value ?? attribs.something).ToString()

The only downside would be that the attribs.something would be assigned a value (itself, in this example) even if entry.Properties["something"].Value was null - which could be expensive if the .something property did some other processing and/or this line executes a lot (like in a loop).

Answer 3

If you are targeting the .NET Framework 3.5, the most elegant solution would be an extension method in my opinion.

public static class ObjectExtensions
{
    public static string NullSafeToString(this object obj)
    {
        return obj != null ? obj.ToString() : String.Empty;
    }
}

Then to use:

attribs.something = entry.Properties["something"].Value.NullSafeToString();

Answer 4

Can you not do:

attribs.something = entry.Properties["something"].Value as string;

Answer 5

How about using an auxiliary method like this:

attribs.something = getString(
    entry.Properties["something"].Value, 
    attribs.something);

static String getString(
    Object obj,
    String defaultString)
{
    if (obj == null) return defaultString;
    return obj.ToString();
}

Alternatively, you could use the ?? operator:

attribs.something = 
    (entry.Properties["something"].Value ?? attribs.something).ToString();

(note the redundant ToString() call when the value is null)

Answer 6

In C# 6.0 you can do it in a very elegant way:

attribs.something = entry.Properties["something"].Value?.ToString();

And here is an article about new null-conditional operator.