Until now, this have been quite painful. Visual Studio 2010, however, has a new feature which opens up a lot of new possibilities; Config Transformations. This is a very cool feature and triggers when you publish your web application within Visual Studio.

Here is an example on how to handle advanced configurations and make them available locally too for testing and debugging purposes.

The challenge:

• I want different config files for different environments.
• I want to test different configurations locally and be able to debug them on my machine with a simple change. This means I must be able to compile my web.config file dynamically when building
• I want my own settings which does not affect the configurations for my teammates.

XmlTransformation task to the rescue!

With the new XmlTransformation task for MSBuild, it is possible to manually trigger config transformations. This is great news because then we can control which files will be transformed and when they will be transformed. I can make more complex configurations and also have my own transformations which are personal and not checked into the version control system.

First, I would like to be able to test the different configurations. Lets say I have a web application which will behave different in different environments. This could be controlled in a database or it could be controlled in a config file.

As an example, I have created a simple solution with 2 themes, one red and one blue theme. Changing the configuration, should also change the theme on the web site. In order to achieve this I have created 2 themes in my solutions with a stylesheet for each theme that will set the background color of the header for the default ASP.NET site that comes with Visual Studio:

2 themes, one red and one blue

In order to be able to change this, I create some configurations in the Configuration manager in Visual Studio:

With the configurations, I am able to create additional transformation files for web.config:

Transformations files

Also notice that I have a Web.master.config file and a Web.mysettings.config file. The master file is the base file that will be used for all transformations. This should contain the settings which is most common for the different configurations. The mysettings file is my personal config file which I use for my personal configurations. For instance, I like to use Fiddler and this contains transformations for adding Fiddler proxy to the web.config file.

The content of the Web.mysettings.config file:

<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
    <system.net>
        <defaultProxy xdt:Transform='Insert'>
            <proxy proxyaddress="http://127.0.0.1:8888"/>
        </defaultProxy>
    </system.net>
</configuration>

Selecting the debug – blue configuration should result in the standard blue color for the default ASP.NET site when running/debugging the web application:

Selecting the debug – red configuration should result in having a red header in the web site:

In real life, a lot of different appsettings could be different for the different configurations.  In this example, the Web.debug – red.config file only contains

<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
    <system.web>
        <pages xdt:Transform="SetAttributes" theme="Red" />
    </system.web>
</configuration>

which will change the theme of the pages element.

Now, here comes the real magic. This is the code you have put into the project file of the web application to be able to modify the Web.config file. Edit the project file and paste this before the </Project> closing element

<UsingTask TaskName="TransformXml" AssemblyFile="$(MSBuildExtensionsPath)\Microsoft\VisualStudio\v10.0\Web\Microsoft.Web.Publishing.Tasks.dll" />
  <!-- This is a hack to perform the master => transform without mysettings of web.config when publishing the website. It will only trigger on -->
  <!-- publish within Visual Studio. It actually overrides the TransformWebConfig Target in the original Microsoft.Web.publishing.targets file, -->
  <!-- but since it is empty by default, it should work fine! -->
  <Target Name="TransformWebConfig">
    <Message Text="%09 ------------- Transforming web.config.master =&gt; web.config with $(Configuration) transformations --------------" />
    <TransformXml Source="web.master.config" Transform="web.$(Configuration).config" Destination="web.config" />
  </Target>
  <Target Name="BeforeBuild">
    <Message Text="%09 ------------- Transforming web.config with $(Configuration) transformations --------------" />
    <TransformXml Condition="Exists('web.mysettings.config')" Source="web.master.config" Transform="web.$(Configuration).config" Destination="web.transformed.config" />
    <TransformXml Condition="Exists('web.mysettings.config')" Source="web.transformed.config" Transform="web.mysettings.config" Destination="web.config" />
    <TransformXml Condition="!Exists('web.mysettings.config')" Source="web.master.config" Transform="web.$(Configuration).config" Destination="web.config" />
  </Target>
  <Target Name="AfterBuild">
    <!--<Delete Condition="Exists('web.mysettings.config')" FiThe BeforeBuoilles="web.transformed.config" />-->
  </Target>

Some comments on the code:

• The TransformXml task comes with Visual Studio 2010, so all you have to do is make a reference to it with the using statement.
• In the BeforeBuild Target,  this is where the transformations take place. This makes it possible to dynamically create Web.config every time a build triggers.
• Using Source and Destination, it is possible to do transformations to all kind of XML file types, not only Web.config.- You could have appSettings.config, connectionsTrings.config etc. It would also be possible to make more hierarchical transformations by doing more than one transformation. Lets say there are some common settings for the red configuration which should be transformed in all environments, it would be possible to have this in a separate config file that will be transformed into the final web.config file.
• The AfterBuild target should clean up the temporary config files. However, there seems to be a bug with the TransformXml task locking the files, so lets hope Microsoft fixes this in a future version.
• The Web.mysettings.config transformation only triggers if there is a mysettings file available. This means not all teammembers have to create this file if they don't need to.
• The target TransformWebConfig is a minor hack. In order to prevent the mysettings transformation when doing a Publish… within Visual Studio, I had to find a target in the Publish… event which triggers only when publishing. This target actually does nothing in the default Microsoft.Web.Publishing.targets file, so that's the reason for overriding this particular target. I wish it would be possible to actually hook into the publish event in Visual Studio through MSBuild, but that seems impossible. And using a target in MSBuild also overrides the target without having the option to call the base target which is overridden, so anything you do in that target will not be continued in the Microsoft.Web.Publishing.targets file. Lets hope MS don't put anything into that target in the future. I also tried to use DependsOnTargets, but that seems to trigger the target depending on, not listening to wheter the target has been run. That's a big difference.

Conclusion

Using the TransformXml task is a pretty simple solution to a complex problem. It comes with Visual Studio 2010 and makes environmental and application specific configurations much simpler to handle in real life. For Visual Studio 2008 and earlier, you still need to think different. Have a look at Andreas post on how to make complex transformations using T4 templates.

You can download the sample solution here: ConfigExample.zip.

The problem:

• I want to add new controls to a page. Clicking a button adds a new control to the page.
• The new control should remember its state through ViewState and postback events should work as normal.

The solution:

• I can add the controls to a Panel or Placeholder and I have to do it in an early stage in the page lifecycle.
• Some experiments and thoughts
  • The dynamically added controls needs to be added to the page on every postback. It is not possible to add a new control and forget it. This means I need to have a loop where the controls are added to the page.
  • The ID of the control need to be the same on every postback in order for the control to remember its state through ViewState.
  • Doing some testing, I tried adding the controls in PreInit. This is where Microsoft recommends to add dynamically created controls. The only problem here is that the ViewState is not available at this stage. So I am not able to track how many controls that have been added to the page. I have a property NumberOfDynamicControls which holds how many dynamically controls that have been added. The same goes with Init, no luck. The ViewState is loaded between Init and Load.
  • You can add controls to the page in almost any event (PreInit, Init, Load, postback event etc.) and it will render fine. However, the ViewState will not be tracked and it is not possible to add and render more than one control.
  • The only solution I found was to override the LoadViewState event and add the controls there. This seems like a hack, and probably is, but everything seems to work fine regarding ViewState tracking and postback events.
  • I need to have the dynamic control available as an invisible "ghost" control before it is "added" to the page. This is to keep track of the state of the control. When clicking the "Add" button, the ghost control is set visible, although it's already there.

Here is the code:

This is the HTML markup. I'm having a simple Panel and a button. Everytime I click the Add button, a new dynamically created button is added to the page.

<asp:Panel runat="server" ID="Panel1" >
 <asp:Button Text="Add" runat="server" OnClick="AddControlToPanel" />
 </asp:Panel>   

   

I have to initialize a "ghost" control. The dynamically created button is actually added to the page before it is visible. This is to track ViewState. Clicking the Add button makes the ghost control visible:

 protected void AddControlToPanel(object sender, EventArgs e)
        {
            Button newButton = Panel1.FindControl("ButtonDynamic" + (NumberOfDynamicControls - 1)) as Button;
            if (newButton != null)
            {
                newButton.Visible = true;
                newButton.Text = "New button";
                NumberOfDynamicControls++;
            }
        }

Here is the tracking of number of dynamically created controls added to the page. The value is stored in the ViewState.

 protected int NumberOfDynamicControls
        {
            get { return ViewState["numberOfDynamicControls"] == null ? 1 : (int)ViewState["numberOfDynamicControls"]; }
            set { ViewState["numberOfDynamicControls"] = value; }
        }

Here comes the real magic. By overriding the LoadViewState and rebuilding the dynamically added controls, everything works as expected.

 protected override void LoadViewState(object savedState)
        {
            base.LoadViewState(savedState);
            if (IsPostBack)
            {
                InitializeDynamicButtons(NumberOfDynamicControls);
            }
        }

protected void InitializeDynamicButtons(int numberOfButtons)
        {
            for (int i = 0; i < numberOfButtons; i++)
            {
                Button dynamicButton = new Button();
                Panel1.Controls.Add(dynamicButton);
                dynamicButton.ID = "ButtonDynamic" + i;
                dynamicButton.Click += DynamicButton_Click;
                dynamicButton.Visible = false;
            }
        }

The dynamically created button also has a click event:

 void DynamicButton_Click(object sender, EventArgs e)
        {
            Button button = (Button) sender;
            button.Text = "Clicked!";
        }

Before:

The page before adding the dynamic buttons

After:

The added buttons. Notice I have clicked the middle button and the state is managed.

Here is the complete code:

DynamicControls

If you know some other good ways to achieve this, let me know!

The challenge

I want to create a more dynamic page tree than the standard EPiServer PageTree. More like an Accordion panel which has 2 or 3 levels (doesn't matter) and all available nodes are expanded by default. The real challenge is to get the whole page tree with all nodes expanded (not only the nodes which are selected) and setting correct class on the expanded items. Whether this is an accordion or another cool menu script is all the same.

The Solution

Start out with the default PageTree control in EPiServer controls.

Things to notice:

• "ExpandAll" is set to true. This will dump the whole tree, not just the nodes which are selected by the user.
• Only the *Expanded* templates are in use for Top and Item (ie.ExpandedTopTemplate).  When using "ExpandAll" these are the templates used, not the regular Top Template and ItemTemplate.
• <%# GetExpandedClass(Container.DataItem) %> – This is the magic for setting the correct style on the expanded items. In addition there is a "selected" class on the selected menu item

The Codebehind looks like this:

Things to notice:

• LeftmenuPageLink is just an example on how to set the start point for the left menu.
• GetExpandedClass is the method that sets the correct class on the <li>. This is done by checking if the page in the tree is available in PageTree.OpenPages. This is what makes it possible to make the dynamic menu. If the OpenPages method was not available, it would not be possible to highlight the expanded nodes without traversing each node or doing some javascripting.

The output should look something like this

The result will look something like this:

After adding the Accordion script, the Top items should collapse and only the expanded section should be visible. When moving the mouse over another section it should expand, but not highlight. The final result will look something like this.

Conclusion

Using dynamic menus could give the visitor a better experience. Whether its an Accordion panel or some other fancy scripted menu doesn't matter. Anyway you will have to dump the whole tree to a certain level (2 levels in this example) and set the correct classes on the elements to get the styling correct. The magic is the "PageTree.OpenPages" method which helps a lot in this scenario.

Knut, remember that Regular Expressions are very handy to clean up a lot of messy code.

Here is an example:
The following function call results in a code analysis warning:

DBHelper.SetPropertyFromDB(m_City, dr("CITY"))

It's a helper function that returns the typed value from a DBValue. Not really useful these days with NHibernate or Typed Datasets, but it's code from an old application. Here is the signature of the code:

Shared Sub SetPropertyFromDB(ByRef pProperty As Object, ByVal value As Object)

The warning reported is:

"Warning: Implicit conversion from 'Object' to 'String' in copying the value of 'ByRef' parameter 'pProperty' back to the matching argument."

To fix this, I created a new method that returns the correct typed value instead of returning the referenced parameter and marked the old method "Obsolete":

Public Shared Function GetDBValue(ByVal pProperty As Object, ByVal dbValue As Object) As Object

Now, I had to rewrite all the calls to the function (several hundred calls). This included returning the typed value into the same variable as the first parameter in the function call, like this:

m_City = DBHelper.GetDBValue(m_City, dr("CITY"))

This is easily achieved by using Regular Expressions in the "Find and Replace" dialog in Visual Studio:

Find What:

DBHelper.SetPropertyFromDB\({.*},

(note: the \ escapes the ( and the expression group is marked by a {})

Replace with:

\1 = DBHelper.GetDBValue(\1,

(note: the \1 will represent the expression group)

Pretty simple, and very powerful

http://forums.asp.net/p/1012442/2951765.aspx#2951765

HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) +        VirtualPathUtility.ToAbsolute(HttpContext.Current.Request.ApplicationPath)

This will return http://subdomain.domain.com/applicationname

You can drop those AppSettings with ApplicationPath

First off, I won't say that this is the one and only way you should use Log4Net, but it handles most of the scenarios I can think of.  Some people think that one should not write wrappers for the loggers and use the logging framework directly in the class, but to be honest I like the wrapper because it makes it very simple to use the logging framework without too much knowledge on how it works. I would say that 95% of what is being logged, is typically errors and debug/useful information. I can't see any problem using a wrapper as I get the information I need from the loggers.

Goals with this log configuration

• Most important is of course logging errors. All errors should be logged.
• Errors should be logged in a global file on the server that will role once a day.
• Errors should be sent by email.
• It should be possible to notify important information by email
• It should be easy for the developers to use the logging framework
• It should be possible to change log-level without restarting the application

Configuration and setup

Log4Net consists of only one DLL. Get the latest version and put it in your bin folder. Make a reference to it in the Web Application Project.

Log4net.config

Create a new config file in the root of your Web Application. Name it Log4Net.config and paste the following code:

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

    <configSections>

        <section name="log4net" 
        type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />

    </configSections>

    <log4net>

        <appender name="RollingLogFileAppender"
            type="log4net.Appender.RollingFileAppender">

            <threshold value="INFO" />

            <file value="Log\[applicationname].log" />

            <appendToFile value="true" />

            <rollingStyle value="Date" />

            <datePattern value="'.'yyyyMMdd'.log'" />

            <layout type="log4net.Layout.PatternLayout">

                <conversionPattern value="%date [%thread] %-5level
                  %logger %X{user} %X{url} - %message%newline" />

            </layout>

        </appender>

        <appender name="SmtpAppenderError" 
                  type="log4net.Appender.SmtpAppender">

            <!--Set threshold for this appender-->

            <threshold value="ERROR" />

            <to value="[someone]@[somewhere.com]" />

            <from value="[someone]@[somewhere.com]" />

            <subject value="Error from [applicationname]" />

            <smtpHost value="[100.100.100.100]" />

            <bufferSize value="1" />

            <lossy value="false" />

            <layout type="log4net.Layout.PatternLayout">

                <conversionPattern value="%date %-5level
                %logger %X{user} %X{url} - %message%newline" />

            </layout>

        </appender>

        <appender name="SmtpAppenderNotify"
                  type="log4net.Appender.SmtpAppender">

            <!--Set threshold for this appender-->

            <threshold value="INFO" />

            <to value="[someone]@[somewhere.com]" />

            <from value="[someone]@[somewhere.com]" />

            <subject value="Error from [applicationname]" />

            <smtpHost value="[100.100.100.100]" />

            <bufferSize value="1" />

            <lossy value="false" />

            <layout type="log4net.Layout.PatternLayout">

                <conversionPattern value="%date - %message%newline" />

            </layout>

        </appender>

        <root>

            <level value="Error" />        

        </root>

        <logger name="Application">

            <!--Set level for this logger-->

            <level value="INFO" />

            <appender-ref ref="RollingLogFileAppender" />

            <appender-ref ref="SmtpAppenderError" />

        </logger>

        <logger name="Notify">

            <!--Set level for this logger-->

            <level value="INFO" />

            <appender-ref ref="RollingLogFileAppender" />

            <appender-ref ref="SmtpAppenderNotify" />

        </logger>

    </log4net>

</configuration>

Some comments on the Log4net.config file:

• The RollingFileAppender is great for rolling the logfile once a day.
  • It has a threshold of INFO, meaning it will log anything from the application except debug information
  • The logfiles are created in a subdirectory of web root. This should be changed on the production server to not expose information about the application.
  • The datePattern is specifying how the rolling files are named. The current day will be named "applicationname.log" and yesterdays file will be named "applicationname.log.20081211.log". The rolling file extension (.log)  makes it easy to open the file in the same editor as the current log. All files will be sorted correctly when using the ISO style date in the filename.
  • In the conversionPattern you will see two speacial entries with the following format: %X{name}. These are custom formats which can be used for special purposes. This configuration adds the authenticated username and the url which fails if there is an error. This is useful information.
• The SmtpAppenders are used for sending emails. It's really not my favourite configuration, spamming the developers or some other people with emails when some errors occur, but some like it.
  • The threshold is different for the two SmtpAppenders, as is the subject of the email.
  • The buffersize is set to 1 in the example, meaning that the email is sent right away when an error occur. Increasing the buffer will hold the email until the buffer is reached. This can be useful on the production server, especially for the Notify appender as it is probably not that important to notify right away.
  • Lossy is set to false, also to send the email right away. It is possible to hold the email until an evaluator is triggered, for instance when a error occurs. Setting lossy to true requires an evaluator.
  • It is possible to add filters to the appenders to determine which emails should be sent and which to drop.
• There are two specific loggers that the application will use. The root logger can be used to log 3.party libraries also using Log4Net. I like to use specific loggers in the application and enabling the root logger if I am tracing an error where I need more information from 3.party libraries, ie. NHibernate or other frameworks using Log4net. Remember to set the level for the logger. If not set, the default level is WARN, which means INFO messages will not be logged.

To be able to use the Log4Net.config file instead of putting everything into web.config, you will need to add the following line to AssemblyInfo.vb:

<Assembly: log4net.Config.XmlConfigurator(ConfigFile:="Log4Net.config", Watch:=True)>

The advantage of separating the Log4Net configuration is that it is possible to change the configuration of the logging without restarting the application by changing web.config.  It also gives an better overview of the configuration, not having to browse through web.config to find the logging configuration.

Logging unhandled errors

All unhandled errors should be logged, which is pretty easy to achieve in web applications. Here is the Global.asax file:

Imports System.Web

Imports log4net

Imports MainLib

Public Class [Global]

    Inherits System.Web.HttpApplication

    Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires when the application is started

        ' Initialize the logger in this context.

        LogManager.GetLogger(Me.GetType)

        LogHandler.LogInfo("============================", LogHandler.LogType.General)

        LogHandler.LogInfo("    Starting application", LogHandler.LogType.General)

        LogHandler.LogInfo("============================", LogHandler.LogType.General)

    End Sub

    Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires when the session is started

    End Sub

    Sub Application_BeginRequest(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires at the beginning of each request

    End Sub

    Sub Application_AuthenticateRequest(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires upon attempting to authenticate the use

    End Sub

    Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires when an error occurs

        LogHandler.LogError("Unhandled exception occured!",
        HttpContext.Current.User, HttpContext.Current.Request.Url,
        HttpContext.Current.Server.GetLastError())

    End Sub

    Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires when the session ends

    End Sub

    Sub Application_End(ByVal sender As Object, ByVal e As EventArgs)

        ' Fires when the application ends

    End Sub

End Class

Comments on Global.asax

• I have added some information logging in the Application_Start event. This will trigger every time the applications starts or recycles. If this occurs often you probably have some problems with resources on the server, ie. too little memory available for the application.
• Application_Error occurs every time an unhandled error occurs. Use this to log all errors not logged elsewhere.
• I have to initialize the logging framework in Application_Start by calling

  LogManager.GetLogger(Me.GetType).  I'm not sure whether this is a bug or by design. It is not possible to let the LogHandler do the initialization. LogHandler is a wrapper class located in another assembly, maybe that is a problem, without really knowing why. LogManager is a class in Log4Net.

The LogHandler class

Imports System.Security.Principal

Imports log4net

Public Class LogHandler

    Const _defaultApplicationLogger As String = "Application"

    Public Enum LogType

        General

        Notify

    End Enum

    Public Shared Sub LogError(ByVal message As String, ByVal [error] As Exception)

        Dim logger As ILog = LogManager.GetLogger(_defaultApplicationLogger)

        If Not [error].InnerException Is Nothing Then

            [error] = [error].InnerException

        End If

        If logger.IsErrorEnabled Then

            logger.Error(message, [error])

        End If

    End Sub

    Public Shared Sub LogError(ByVal message As String, _

                                ByVal user As IPrincipal, ByVal url As Uri, _

                                ByVal [error] As Exception)

        SetOptionalParametersOnLogger(user, url)

        LogError(message, [error])

    End Sub

    Public Shared Sub LogInfo(ByVal message As String, ByVal type As LogType)

        Dim logger As ILog = Nothing

        If type = LogType.Notify Then

            logger = LogManager.GetLogger(LogType.Notify.ToString)

        Else

            logger = LogManager.GetLogger(_defaultApplicationLogger)

        End If

        If logger.IsInfoEnabled Then

            logger.Info(message)

        End If

    End Sub

    Public Shared Sub LogWarning(ByVal message As String, ByVal [error] As Exception)

        Dim logger As ILog = LogManager.GetLogger(_defaultApplicationLogger)

        If Not [error].InnerException Is Nothing Then

            [error] = [error].InnerException

        End If

        If logger.IsWarnEnabled Then

            logger.Warn(message, [error])

        End If

    End Sub

    Public Shared Sub LogWarning(ByVal message As String, _

                                 ByVal user As IPrincipal, ByVal url As Uri, _

                                 ByVal [error] As Exception)

        SetOptionalParametersOnLogger(user, url)

        LogWarning(message, [error])

    End Sub

    Private Shared Sub SetOptionalParametersOnLogger(ByVal user As IPrincipal, ByVal url As Uri)

        'set user to log4net context, so we can use %X{user} in the appenders

        If Not user Is Nothing AndAlso user.Identity.IsAuthenticated Then

            MDC.[Set]("user", user.Identity.Name)

        End If

        'set url to log4net context, so we can use %X{url} in the appenders

        MDC.[Set]("url", url.ToString())

    End Sub

End Class

Comments on LogHandler

• It's a pretty simple class which is easy to use. I could have added more wrapper methods with overload
• The LogType enum defines whether the message should be notified (emailed) or not.
• If I forget to set the level on the logger in the Log4Net.config, the logger.IsInfoEnabled will return false.
• I am using the MDC class in the Log4Net framework to add the custom entries in the logged message for user and url (see Log4Net.config above)

Handling an error and notifying with success

Sometimes when you know what could go wrong and you want to display a nice error message to the user, you could handle the error and display an errormessage to the user.

Example:

Private Function CreateUser() As User

    Dim userName As String = TextBoxUserName.Text

    Dim password As String = TextBoxPassword.Text

    Try

        Dim user As New User(userName, password)

        LogHandler.LogInfo("Yahoo! User with username " & userName & " created.",
                           LogHandler.LogType.Notify)

        Return user

    Catch iunex As InvalidUserNameException

        PageTools.DisplayError(Page, iunex)

        LogHandler.LogWarning("Error creating user with username " & userName, iunex)

    Catch ipex As InvalidPasswordException

        PageTools.DisplayError(Page, ipex)

        LogHandler.LogWarning("Error creating user with password " & password, ipex)

    End Try
    Return Nothing

End Function

Comments on CreateUser:

• If successful, a notification is sent by email by using the LogInfo method and using LogHandler.Logtype.Notify
• The User class will throw InvalidUserNameException or InvalidPasswordException in the credentials are invalid. I wish to display the errors to the user instead of displaying a general error page. In real life I would probably use some validation before calling the User constructor, but this is only an example.
• In addition to displaying the error to the user, the error is logged as a warning.This means it will be logged, but no email will be sent to the mailbox as this is not an error in the application.
• All other exceptions raised when creating the user will be caught in Application_Error in Global.asax and logged there.

Loginformation

Ok, now I have all the code I need to do decent logging. So what do I expect to see in the logfiles?

When building the application in DEBUG mode I will see the following in the logfile:

2008-12-11 16:56:24,453 [14] INFO  Application (null) (null) - ============================
2008-12-11 16:56:24,468 [14] INFO  Application (null) (null) -     Starting application
2008-12-11 16:56:24,468 [14] INFO  Application (null) (null) - ============================
2008-12-11 16:56:25,937 [14] WARN Application 3DX5G3J\knuth http://localhost/fdb/default.aspx -
                                  Error creating user with username Knut Hamang
DAL.InvalidUserNameException: Username is already in use! Please select another username.
   at DAL.User..ctor(String username, String password) in C:\Knut\code\Repository\Internal_Systems\fdb\trunk\DAL\User.vb:line 97
   at fdb.default.CreateUser() in C:\Knut\code\Repository\Internal_Systems\fdb\trunk\Web\default.aspx.vb:line 69

Building in RELEASE  mode I get the following information:

2008-12-11 16:59:21,406 [14] INFO  Application (null) (null) - ============================
2008-12-11 16:59:21,421 [14] INFO  Application (null) (null) -     Starting application
2008-12-11 16:59:21,421 [14] INFO  Application (null) (null) - ============================
2008-12-11 16:59:22,812 [14] WARN Application 3DX5G3J\knuth http://localhost/fdb/default.aspx -
                             Error creating user with username Knut Hamang
DAL.InvalidUserNameException: Username is already in use! Please select another username.
   at DAL.User..ctor(String username, String password)
   at fdb.default.CreateUser()

The difference is the stacktrace. I get the stacktrace in both cases, but I also get the line numbers in DEBUG mode. I can still read the trace and locate the method in the file that throws the error. The conclusion is that I get enough information to trace and fix the error, if there is one.

Please leave any comments on the configuration, and feel free to discuss different logging strategies for Web Applications.

Download it here.

Regarding PDF creation, iTextSharps main function is generating PDF from scratch, not converting them from HTML. The library has a really understandable API for developers that are not familiar with the PDF specification, me beeing one of them.

Playing around with the API and reading some news lists and forum posts, I finally managed to get a working sample on how to export a GridView to PDF. This is a pretty simple sample, but you can play around with the API to add more formatting and do your stuff. Actually you can export anything in the XHTML, providing the markup is legal. However, not all html tags are supported. The intention of the author was not to make a HTML2PDF converter, but more like create PDF's from HTML if the markup supports the engine. So you will probably not be able to convert dynamic content you do not have control over, but it's excellent for creating reports etc. Supported tags are: "ol ul li a pre font span br p div body table td th tr i b u sub sup em strong s strike h1 h2 h3 h4 h5 h6 img"

So how does it work, then? Well, first you need to get the latest version of iTextSharp. Just place the dll to your bin folder in your Web Application Project (you're not using Web Projects, are you ) and add a reference to it. Then create a new page, add a PlaceHolder to it, The placeholder will be the section of the HTML that you will export to PDF. You can add some more controls to the placeholder if you need. Inside the placeholder add a GridView and bind it to your datasource.

Add a ASP:Button to the page. This will trigger the export. The code when the button is clicked is doing all the exporting stuff:

Almost there. Clicking the button will result in an exception:

Control 'GridView1' of type 'GridView' must be placed inside a form tag with runat=server.

This is because we are trying to render the PlaceHolder control in a stream and not in a WebForm. A neat .NET security feature to prevent Injection attacks. This exception is simply ignored by adding the following code to the page:

Now, clicking the button again results in another Exception:

RegisterForEventValidation can only be called during Render();

Again, a security feature of .NET. Ignore this excpetion by setting EnableEventValidation="False" in the Page header. If you are concerned about the security of the page, please check official documentation of the features that has been disabled for the page.

Now, clicking the button should result in a PDF document. If not, debug the application and check Debut Output window for exceptions. Probably the XHTML in the placeholder is not valid.

Note that I am using HTMLWorker class instead of the HtmlParser class in the iTextSharp library. According the the author, the HTMLParser is not supported. I tried both, and the HTMLWorker swallows a lot more HTML markup than the HtmlParser.

You probably also want to clean the HTML before parsing it with the HTMLWorker. Typically you want to remove javascript postbacks, anchors etc. from the GridView. This can be achieved with the following code:

You can also extend the HTMLWorker class making it more specialized for your purpose. For instance it would be great to be able to define pagebreaks in the final PDF document. Simply create a new class inherited from HTMLWorker.

Now, simply replace the HTMLWorker with the extended version and add a <newpage /> element to the HTML in the placeholder where you want a new page.

There are some css styles not supported by default. For instance it is not possible to set the background-color style for an image or tablecell/-row. The only solution for adding more style support is changing the iTextSharp source. It's pretty simple, however. Open \text\html\simpleparser\FactoryProperties.cs. In the InsertStyle method add the following code to the foreach loop:

Update: Another example for adding border color to a table:

First, set the border style for the table, ie. style="border-color: #ff0000;"

Then again, you need to apply the style to FactoryProperties.cs file as in the example above.

else if (key.Equals(Markup.CSS_KEY_BORDERCOLOR))

{

    Color c = Markup.DecodeColor(prop[key]);

    if (c != null)

    {

        int hh = c.ToArgb() & 0xffffff;

        String hs = "#" + hh.ToString("X06", NumberFormatInfo.InvariantInfo);

        h["border-color"] = hs;

    }

}

In addition you need to alter the output of the table as there is no default "bordercolor" style property in the IncTable class.

Open IncTable.cs and change the following code in the BuildTable method:
Existing code:

for (int row = 0; row < rows.Count; ++row) {

    ArrayList col = (ArrayList)rows[row];

    for (int k = 0; k < col.Count; ++k) {

        table.AddCell((PdfPCell)col[k]);

    }

}

Replace with:

String bordercolor = (String)props["border-color"];

for (int row = 0; row < rows.Count; ++row)

{

    ArrayList col = (ArrayList)rows[row];

    for (int k = 0; k < col.Count; ++k)

    {

        PdfPCell cell = (PdfPCell)col[k];

        cell.BorderColor = Markup.DecodeColor(bordercolor);

        table.AddCell(cell);

    }

}

This will change the border color on the cell in the table. Hint: It could be wise to check if the cell already has a border color before overwriting it with the table border color.

Recompile and add the new DLL to your project.

Happy Coding!