Given the following simplified code block in ASP.NET
<% foreach( item in Model) { %>
<%=item.OriginalText.OriginalText1 %>
<%} %>
OriginalText is a class which may be null. I am looking for a simple (clean) way to check for this null and return an empty string ("") instead.
<% foreach( item in Model) { %>
<%= (item.OriginalText == null) ? string.Empty: item.OriginalText.OriginalText1 %>
<%} %>
use this one:
<%=item.OriginalText == null ? "" : item.OriginalText.OriginalText1 %>
If you are in control of the code, you could also consider implementing the null object pattern, thus avoiding the need to check for null.
The benefit to this approach is that you no longer have to check every time you want to use the object (Don't Repeat Yourself), but it does depend upon how you are creating your objects, and how much control you have.
Something like:
public class NullOriginalText : OriginalText
{
public string OriginalText1 { get; private set; }
public NullOriginalText()
{
OriginalText1 = string.Empty;
}
}
public class ModelItem
{
public OriginalText { get; private set; }
public ModelItem()
{
OriginalText = new NullOriginalText();
}
public ModelItem(OriginalText originalText)
{
if (originalText == null)
{
OriginalText = new NullOriginalText();
}
else
{
OriginalText = originalText;
}
}
}
The cleanest way I've found to do this is with an extension method.
Example:
public static class OriginalTextExtensions
{
public static string OriginalText1SafeString(this OriginalText original)
{
return original == null ? string.Empty : original.OriginalText1;
}
}
and then you'd use it like this:
<% foreach( item in Model) { %>
<%= item.OriginalText.OriginalText1SafeString() %>
<%} %>
<% foreach( item in Model) { %>
<%= item.OriginalText == null ? string.Empty:
item.OriginalText.OriginalText1 %>
<%} %>
Depending on the situation the Null coalescing operator may help as well.
<% foreach( item in Model) { %>
<%= item.OriginalText.OriginalText1 ?? String.Empty %>
<%} %>
