Logging in MVC Part 5 – The Model and Data Layer

Introduction

This is the 5th article in a series on MVC logging.
Our sample website now has Elmah, NLog, Log4Net and Health monitoring set up and working. Now it is time to start work on our log reporting website by tying them all together.

Preparing the database

ASP.NET Health Monitoring logs a lot of different types of messages but there is no way to differentiate whether a message is just for information purposes or whether it is an error message that may need attention. So to address this issue, let’s create a new table called “aspnet_WebEvent_ErrorCodes” and introduce a column called “Level” which will map each message eventcode to either “Info”, “Error”.
The reason for doing this is so that we have a common “Level” attribute that we can use for all of our logging providers and this will allow us to later on filter all messages by their Log Level. Elmah for example will only be used to log unhandled exceptions so the LogLevel for our Elmah messages will always be “Error”.
Here is the database script necessary to add the new table to our database:

/****** Object:  Table [dbo].[aspnet_WebEvent_ErrorCodes]   

Script Date: 07/29/2010 09:56:45 ******/
IF  EXISTS (SELECT * FROM sys.objects 

WHERE object_id = OBJECT_ID(N'[dbo].[aspnet_WebEvent_ErrorCodes]') 

AND type in (N'U'))
DROP TABLE [dbo].[aspnet_WebEvent_ErrorCodes]
GO
/****** Object:  Default [DF_aspnet_WebEvent_ErrorCodes_Level]    

Script Date: 07/29/2010 09:56:45 ******/
IF  EXISTS (SELECT * FROM sys.default_constraints 

WHERE object_id = OBJECT_ID(N'[dbo].[DF_aspnet_WebEvent_ErrorCodes_Level]') 

AND parent_object_id = OBJECT_ID(N'[dbo].[aspnet_WebEvent_ErrorCodes]'))
Begin
IF  EXISTS (SELECT * FROM dbo.sysobjects 

WHERE id = OBJECT_ID(N'[DF_aspnet_WebEvent_ErrorCodes_Level]') AND type = 'D')
BEGIN
ALTER TABLE [dbo].[aspnet_WebEvent_ErrorCodes] 

DROP CONSTRAINT [DF_aspnet_WebEvent_ErrorCodes_Level]
END

End
GO

Logging in MVC Part 4 – Log4Net

Introduction

In this article we will quickly add Log4Net into the website so that later on we can decide whether to use Log4Net or NLog to log our custom messages.
Log4Net is a very widely used logger and it is quite likely that you have 3rd party dependencies in your website that already use Log4Net so it can be a good idea to track any messages that it logs.

Log4Net

The steps we need to follow are:
1. Download Log4Net
2. Add a reference to Log4Net
3. Add a table in our database to store the Log4Net logs
4. Modify the web.config file for Log4Net
5. Implement a Log4NetLogger that implements our ILogger interface.

Logging in MVC Part 3 – NLog

Introduction

In the previous article we implemented Health Monitoring into our MVC website.
Now we need to provide a way to log our own custom messages so that we can keep track of important events that occur throughout our website.
For example, you may need to log information before and after a financial transaction has occurred on your eCommerce website.
It is easy to write your own logger but as there are already many established logging frameworks already available for .NET I’ve decided to concentrate on 2 of the most popular ones: Log4Net and NLog.
In this article we will concentrate on setting up NLog and in the next article we will take a look at Log4Net.

NLog

Prior to working on this series I had never ever used NLog - I’ve always used Log4Net. However, after spending some time on Rob Connerys blog and looking at his MVC Storefront series and his MVC starter kit I decided to look at NLog so that I have another logging framework in my utility belt. It’s always good to broaden your knowledge and learn a new skill or master a new toolkit.
So what follows is pretty much exactly what Rob Conery did for his MVC starter kit website. However I have extended the default NLog functionality by including 2 new layout renderers.
Here are the steps we need to take to integrate NLog into our website:
1. Download NLog.
2. Create a table in our database to store the NLog messages.
3. Configure our NLog configuration file.
4. Set up a logging interface for our website.
5. Implement an NLog logger that uses our interface to log messages to the database table in step 2.
6. Add some additional layout renders that we will need for NLog.
Let’s tackle each one in order.