Customized Exception Handling

You can add more exception types like database under the "Replace Policy", with different messages.

Wrap Policy Functionality

<add name="Wrap Policy">
<exceptionTypes>
<add name="NonHandledErrors" type="System.Exception" postHandlingAction="ThrowNewException">
<exceptionHandlers>
<add name="Wrap Handler" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.WrapHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling" exceptionMessage="A recoverable error occurred while processing your request, please try after some time" wrapExceptionType="System.Exception" />
</exceptionHandlers>
</add>
</exceptionTypes>
</add>

Our requirement

In our case the exception type will be "BusinessException" (Custom exception) in case of any business related exceptions and and system.Exception for all other un-handled exception.

Here we are defined two error codes and its messages, 100001, 100002.

<add name="Replace Policy">
<exceptionTypes>
<add name="BusinessLayerException" type="System.Exception" postHandlingAction="ThrowNewException">
<exceptionHandlers>

<add name="100001" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.ReplaceHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling" exceptionMessage="No Flight options found for this query" replaceExceptionType="System.ApplicationException" />

<add name="100002" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.ReplaceHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling" exceptionMessage="Not able to book your requrierment" replaceExceptionType="System.ApplicationException" />
</exceptionHandlers>
</add>
</exceptionTypes>
</add>

We found that, the Enterprise Library exception replace handler required some modification and will be able to cope this requirements. It's good to see that Microsoft shared the source code of the exception handling, and thus, modified some classes to meet our requirements.

Code for the entry/exist point in your code

You need to handle the error here

catch (Exception ex)
{
bool rethrow = false;
if (ex.GetType().FullName.Equals("ExceptionHandling.BusinessException"))
{
rethrow = ExceptionPolicy.HandleException(ex, EnumExceptionPolicyTypes.Type.Replace_Policy);
}
else
{

rethrow = ExceptionPolicy.HandleException(ex, EnumExceptionPolicyTypes.Type.Wrap_Policy);
}
if (rethrow)
{
throw;
}
}

Code for all other codes / functions

catch (Exception ex)
{
bool rethrow = ExceptionPolicy.HandleException(ex, EnumExceptionPolicyTypes.Type.Propagate_Policy);
if (rethrow)
{
throw;
}

}

Way to rise raises your own exception

throw new BusinessException("100001");

Customer business exception Class

public class BusinessException : System.ApplicationException
{
public BusinessException() : base() { }
public BusinessException(string message) : base(message) { }
public BusinessException(string message, System.Exception inner) : base(message, inner) {
}