Beware of Null Values in ASP Database Programs

The Active Server Pages HTMLEncode function is great for handling strings that come from a database, especially if the string includes foreign characters. However, you can get into trouble if the string field in the database is empty; that is, it contains a Null. When it hits a Null, HTMLEncode throws a "Type Mismatch" error. Make sure you check for Nulls whenever you are using HTML-encoding. Here's sample routine:

 
<HTML>
<HEAD>
</HEAD>
<BODY>
<% 
Function HTMLEncode(instring)
  If Not IsNull(instring) then
    HTMLEncode=Server.HTMLEncode(instring)
  else 
    HTMLEncode=""
  end if
End function
%>

<%
dbdatastring=Null
Response.Write HTMLEncode(dbdatastring)
dbdatastring="J'ai mal


														Ken Cox
														 
														
															
																
																	
																		
																			
																				
																			
																		
																		
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