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

To do precisely what you're trying to do a helper method can always be used:

CopyIfNotNull(entry.Properties["something"].Value, out attribs.something);

void CopyIfNotNull(string src, out string dest)
{
  if(src != null)
    dest = src;
}

Answer 2

attribs.something  = string.Format("{0}",entry.Properties["something"].Value)

Answer 3

Update 8 years later (wow!) to cover c# 6's null-conditional operator:

var value = maybeNull?.ToString() ?? String.Empty;

Other approaches:

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

I've also used this, which isn't terribly clever but convenient:

public static string ToSafeString(this object obj)
{
    return (obj ?? string.Empty).ToString();
}

Answer 4

Adding an empty string to an object is a common idiom that lets you do null-safe ToString conversion, like this:

attribs.something = ""+entry.Properties["something"].Value;

When entry.Properties["something"].Value is null, this quietly returns an empty string.

Edit: Starting with C# 6 you can use ?. operator to avoid null checking in an even simpler way:

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

Answer 5

attribs.something = String.Format("{0}", entry.Properties["something"].Value);

Not sure about performance though...

Answer 6

Is it somehow possible to do something like Dale Ragan's answer above, but overriding ToString() instead of creating a new NullSafeToString() method? I'd like this (or returning "null") to be the default behaviour. The compiler (Visual C# 2010 Express) doesn't complain when I add the following method to public static class ObjectExtensions, but the method doesn't get called...

public static String ToString(this Object obj)
{
    if (obj == null)
    {
        return "null";
    }
    else
    {
        return obj.GetType().Name;
    }
}