AspectTightlyCoupled.cs

[Serializable]
[MulticastAttributeUsage(MulticastTargets.Method, TargetMemberAttributes = MulticastAttributes.Public)]
public class ServiceErrorInterceptor : MethodInterceptionAspect
{
	public override bool CompileTimeValidate(MethodBase method)
	{
		if (!typeof (ServiceBase).IsAssignableFrom(method.DeclaringType))
		{
			var declaringType = method.DeclaringType;
			var declaringTypeName = "Unknown";
			if (declaringType != null)
				declaringTypeName = declaringType.FullName;
			Message.Write(method, SeverityType.Error, "SEI01", "The target type (" + declaringTypeName + ") does not implement ServiceBase.");
			return false;
		}

		return base.CompileTimeValidate(method);
	}

	public override void OnInvoke(MethodInterceptionArgs args)
	{
		try
		{
			args.Proceed();
		}
		catch (SqlException ex)
		{
			var obj = (ServiceBase) args.Instance;
			if (ex.Message.Contains("The DELETE statement conflicted with the REFERENCE constraint"))
				obj.AddValidationError("This item can't be deleted because it is still used by other items.");
			else
			{
				obj.AddValidationError(GetErrorMessage(ex));
				if (!IsThisSite.RunningLocally)
					ex.ToExceptionless().Submit();
			}
			ErrorReturn(args);
		}
		catch (NotImplementedException)
		{
			// if something's not implemented, just throw it up
			throw;
		}
		catch (Exception ex)
		{
			if (!IsThisSite.RunningLocally)
				ex.ToExceptionless().Submit();
			var obj = (ServiceBase)args.Instance;
			obj.AddValidationError(GetErrorMessage(ex));
			ErrorReturn(args);
		}
	}

	private string GetErrorMessage(Exception ex)
	{
		if(IsThisSite.RunningLocally)
			return "There was a database error. Please try again later. (" + ex.Message + "), (" + ex.GetType().FullName + ")";
		return "There was a database error. Please try again later.";
	}

	void ErrorReturn(MethodInterceptionArgs args)
	{
		try
		{
			var methodInfo = args.Method as MethodInfo;
			if (methodInfo == null)
				return;
			if (typeof (IEnumerable).IsAssignableFrom(methodInfo.ReturnType) || methodInfo.ReturnType.IsValueType)
				if (methodInfo.ReturnType != typeof (void))
					args.ReturnValue = Activator.CreateInstance(methodInfo.ReturnType);
				else
					args.ReturnValue = null;
		}
		catch
		{
			// don't want any errors to take place trying to build the correct return value
			// so just swallow them, and let args.ReturnValue stay whatever it is
		}
	}
}