[Mono-bugs] [Bug 77410][Maj] New - SybaseParameter, Scale throws an InvalidCastException

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Changed by sebastien.robitaille at croesus.com.

http://bugzilla.ximian.com/show_bug.cgi?id=77410

--- shadow/77410	2006-01-30 16:03:18.000000000 -0500
+++ shadow/77410.tmp.1216	2006-01-30 16:03:18.000000000 -0500
@@ -0,0 +1,91 @@
+Bug#: 77410
+Product: Mono: Class Libraries
+Version: 1.1
+OS: 
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Major
+Component: Sys.Data
+AssignedTo: tsenganal at novell.com                            
+ReportedBy: sebastien.robitaille at croesus.com               
+QAContact: mono-bugs at ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: SybaseParameter,Scale throws an InvalidCastException
+
+Description of Problem:
+
+When using the Mono.Data.Sybase provider,
+I have a problem when using a decimal SybaseParameter with a scale of 
+zero and a DBNull value.
+
+The following exception is thrown when accessing the 
+SybaseParameter.Scale getter:
+
+an exception of type: {System.InvalidCastException} occurred
+
+
+After looking at the code (Mono.Data.Tds.TdsMetaParameter.cs),
+I realized that the exception is thrown because a conversion is executed 
+everytime the Scale property is accessed, but there are no test to 
+validate that Value is not the DBNull.Value.
+
+Please, refer to the following code snippet from the TdsMetaParameter.cs 
+file:
+
+public byte Scale {
+	get { 
+		if (TypeName == "decimal" || TypeName == "numeric") {
+			if (scale == 0) { 
+				int[] arr = Decimal.GetBits (
+						Convert.ToDecimal(Value));
+				scale = (byte)((arr[3]>>16) & (int)0xFF);
+			}
+		}
+		return scale;
+	}
+	set { scale = value; }
+}
+
+A quick fix would be to test for Convert.IsDbNull(Value):
+
+public byte Scale {
+	get { 
+		if (TypeName == "decimal" || TypeName == "numeric") {
+			if (scale == 0 && !Convert.IsDbNull(Value)) { 
+				int[] arr = Decimal.GetBits (
+						Convert.ToDecimal(Value));
+				scale = (byte)((arr[3]>>16) & (int)0xFF);
+			}
+		}
+		return scale;
+	}
+	set { scale = value; }
+}
+
+
+Steps to reproduce the problem:
+1. Execute the following code:
+
+IDbDataParameter prm = myCommand.CreateParameter();
+prm.Value = DBNull.Value;				
+prm.ParameterName = "@MyParam";
+prm.DbType = DbType.Decimal;
+prm.Precision = 10;
+prm.Scale = 0;
+
+byte myScale = prm.Scale; // Throws an exception.
+
+Actual Results:
+Exception thrown.
+
+Expected Results:
+No Exception. Zero returned by the Scale parameter.
+
+How often does this happen? 
+Always. 
+
+Additional Information: