I’ve finally gotten around to starting a CodePlex project for publishing SharePoint features called Trentacular SharePoint 2007 Features. The first contribution to the project should reach a broad audience (within the SharePoint population that is) … an ASP.Net 3.5 Upgrade Feature.
The Feature is naturally scoped to a Web Application and adds ASP.Net 3.5 entries to the particular Web Application’s web.config file. It works for both WSS and MOSS and also supports clean deactivation by iterating through the SPWebConfigModification collection and removing modifications by owner instead of recreating the modifications. All modifications are done through a utility class called SPWebConfigModificationHelper which can be taken advantage of alone if you are writing your own modifications.
Before deciding to write this feature, I tried several others that have been published. Each had its own issues, from not supporting clean deactivation to simply just not adding the correct entries. The entries this feature writes were taken from the Visual Studio ASP.Net 3.5 Web.config template.
If you give this Feature a shot, please let me know how it goes.
Greg Galipeau wrote a thorough post on cleaning up your Web Part Gallery that is the basis for this post. To summarize, Greg shares a Feature Receiver he uses as a generic Feature Receiver for all his WebPart Features that simply removes the WebPart having the same name as the Feature’s DisplayName when the Feature is deactivated.
There are a couple of issues with this though:
- It assumes that the WebPart has the same name as the Feature
- It limits the Feature to deploying just a single WebPart
An alternative approach would be to inspect the Feature’s element definitions and extract the exact WebPart names that were deployed, thus resolving the two issues noted above.
Below is the alternative Feature Receiver (it extends the BaseFeatureReceiver I mentioned in my previous post):
public class WebPartFeatureReceiver : BaseFeatureReceiver<SPSite>
{
public override void FeatureDeactivating(SPSite site, SPFeatureReceiverProperties properties)
{
base.FeatureDeactivating(site, properties);
var elements = properties.Definition.GetElementDefinitions(CultureInfo.CurrentCulture);
var webparts = elements.Cast<SPElementDefinition>()
.SelectMany(e => e.XmlDefinition.ChildNodes.Cast<XmlElement>()
.Where(n => n.Name.Equals("File"))
.Select(n => n.Attributes["Url"].Value)
)
.ToList();
var rootWeb = site.RootWeb;
var wpGallery = rootWeb.Lists["Web Part Gallery"];
var galleryItems = wpGallery.Items.Cast<SPListItem>()
.Where(li => webparts.Contains(li.File.Name))
.ToList();
for (int i = galleryItems.Count - 1; i >= 0; i--)
{
var item = galleryItems[i];
item.Delete();
}
}
}
If you are writing SharePoint feature receivers often, you will find there are several lines of code common to just about every feature receiver:
- A cast of properties.Feature.Parent to the appropriate scope (either SPWeb, SPSite, SPWebApplication, or SPFarm)
- Empty implementations of FeatureInstalled and FeatureUninstalling
Provided below is an abstract generic class that now serves as the base class for every feature receiver I write. It eliminates the redundant code by performing the cast for you based on the classes generic type parameter and also goes ahead and implements all the abstract methods, making it so that you to only need to override the actual methods you plan to handle. Your extending feature receiver now will look like the following:
public class MyFeatureReceiver : BaseFeatureReceiver<SPWeb>
{
public override void FeatureDeactivating(SPWeb scope, SPFeatureReceiverProperties properties)
{
// Pointless, but what the heck
base.FeatureDeactivating(scope, properties);
// Now do something with your scope object, in this case an SPWeb
...
}
}And now, the code for the BaseFeatureReceiver:
/// <summary>
/// Base class that makes the feature scope available as an argument to the
/// FeatureActivated and FeatureDeactivating methods
/// </summary>
/// <typeparam name="T">
/// T is the class type of the scope of the feature (SPFarm, SPWebApplication, SPSite, or SPWeb)
/// </typeparam>
public abstract class BaseFeatureReceiver<T> : SPFeatureReceiver
{
public sealed override void FeatureActivated(SPFeatureReceiverProperties properties)
{
FeatureActivated((T)properties.Feature.Parent, properties);
}
public virtual void FeatureActivated(T scope, SPFeatureReceiverProperties properties) { }
public sealed override void FeatureDeactivating(SPFeatureReceiverProperties properties)
{
FeatureDeactivating((T)properties.Feature.Parent, properties);
}
public virtual void FeatureDeactivating(T scope, SPFeatureReceiverProperties properties) { }
public override void FeatureInstalled(SPFeatureReceiverProperties properties) { }
public override void FeatureUninstalling(SPFeatureReceiverProperties properties) { }
}Hope you find this helpful.
Scenario
I have a fairly straight-forward sequential approval workflow that has an EnableModificationActivity that is in scope for just about the entirety of the workflow. My modification form is an ASPX page that gives the user the ability to enable/disable approval steps that have not occurred yet in the workflow. Since the workflow is able to be modified multiple times, I would like the form to reflect the current state of the workflow, meaning it should show which activities are currently enabled or disabled.
Solution
So here is the approach I ended up taking…
- I created a Plain Old CLR Object (POCO) class specific for holding state information my particular workflow that is capable of being XML Serialized. I’ll call this the “State Object” going forward.
- I created a reusable class called “WorkflowStateManager” that is capable of loading and saving single State Objects for a given SPWorkflow. This class is accessible by both the workflow and the modification form.
- Save State Implementation:
- XML serializes the object to a string
- Sets the serialized string on the SPWorkflow list item’s property bag and calls the property bag’s Update() method
- Load State Implementation (Essentially the reverse of the Save State implementation)
- Gets the serialized string from the SPWorkflow list item’s property bag
- XML Deserialize the string into the State Object
- When the workflow is activated, I construct a new State Object, initialize various properties on it, and save it using the WorkflowStateManager.
- As the workflow progresses, I load and update the State Object as needed in the following manner:
- Use the WorkflowStateManager to load the current State Object
- Make workflow decisions based on the State Object’s values
- Make desired changes to the State Object
- Use the WorkflowStateManager to save the State Object
- Now, my modification form is also able to load, manipulate, and save the State Object using the WorkflowStateManager, and in turn expose the current state of the workflow to the user.
I hope this might be of benefit to someone.
I just finished delivering a SharePoint workflow application in which I developed what could be called a start to framework that I would like to reuse in my next project. The framework currently has many features such as:
- An “Object-List Mapping” infrastructure complete with lazy initialization of objects and collections, converters, and caching
- A list item event broker
- Several handy web controls
- Logging
- State management
- Plenty of Utility Helpers
Each major feature is defined with an interface, and there is a single context class scoped to an SPWeb that holds references to each feature provider. For this last application, and I imagine I will do this for most applications going forward, I extended the context class to hold additional references to application-specific business logic helpers and data access interfaces.
In order to accomplish dependency injection of the feature providers, there is a context factory interface that is responsible for constructing and initializing contexts. I implemented a static ”default” context factory that when called upon, it first looks in the SPWeb property bag to see if a predefined custom context factory type has been specified. If it finds one, it constructs a new instance of the custom factory and returns the context from the custom factory’s CreateContext method.
public static class SPAppContextFactory
{
public const string CustomSPAppContextFactoryKey = "custom_context_factory_key";
public static void RegisterSPAppContextFactory<T>(this SPWeb web) where T : ISPAppContextFactory
{
web.AllProperties[CustomSPAppContextFactoryKey] = typeof(T).AssemblyQualifiedName;
web.Update();
}
public static void UnregisterSPAppContextFactory(this SPWeb web)
{
if (web.Properties.ContainsKey(CustomSPAppContextFactoryKey))
{
web.AllProperties[CustomSPAppContextFactoryKey] = null;
web.Update();
}
}
public static SPAppContext CreateSPAppContext(this SPWeb web)
{
// First check Web Properties if an alternate factory is specified
if (web.AllProperties.ContainsKey(CustomSPAppContextFactoryKey))
{
string customFactoryTypeName = web.AllProperties[CustomSPAppContextFactoryKey];
Type customFactoryType = Type.GetType(customFactoryTypeName, true);
ISPAppContextFactory customFactory = (ISPAppContextFactory)Activator.CreateInstance(customFactoryType);
return customFactory.CreateContext(web);
}
// Create the Default Context
return new SPAppContext(web);
}You can now register your applications custom context factory in the FeatureActivated method of a feature receiver. You’ll need to include the namespace of your static factory class in order to make the extension methods available, and then simply call the RegisterSPAppContextFactory extension method .
public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
var web = (SPWeb)properties.Feature.Parent;
web.RegisterSPAppContextFactory<MyCustomContextFactoryClass>();
}
public override void FeatureDeactivating(SPFeatureReceiverProperties properties)
{
var web = (SPWeb)properties.Feature.Parent;
web.UnregisterSPAppContextFactory();
}The context factory now serves as a single place where all dependencies are wired up, and the framework is now able to instantiate custom contexts without being aware of any feature provider implementation.
Disclaimer: the following code requires version 3.5 of the .Net Framework, but can easily be modified to run using .Net 2.0
Scenario
So I was asked to develop a fairly straight forward approval activity in which several users were to be assigned an approval task in parallel. Microsoft offers its ReplicatorActivity to accomplish just this. The gotcha is that when running the ReplicatorActivity in parallel, the CurrentIndex property of the replicator is always the last index value of its child data. So how do you know which ChildData item the replicator is currently executing upon?
Solution
What I came up with seems a little hacky, but has been working beautifully for me. Here it goes…
The replicator contains a DynamicActivities property which holds references to each of the replicated activities it creates. Using Linq, we can easily convert this collection to a list, and then determine the index of the current activity within our newly converted activity list. The following example shows how I am using this method to access the current child data from within a CreateTask activity:
private void createTask_Invoked(object sender, EventArgs e)
{
var createTask = (CreateTask)sender;
string approver = (string)WorkflowUtils
.GetReplicatorChildData(createTask);
...
}And the magic happens within our WorkflowUtils helper class:
public static class WorkflowUtils
{
public static Activity GetTopMostReplicatorChild(Activity activity)
{
var parent = activity.Parent;
if (parent == null)
return null;
if (parent is ReplicatorActivity)
return activity;
return GetTopMostReplicatorChild(activity.Parent);
}
public static object GetReplicatorChildData(Activity activity)
{
var topMostChild = GetTopMostReplicatorChild(activity);
var replicator = (ReplicatorActivity)topMostChild.Parent;
int currentIndex = replicator.DynamicActivities
.ToList()
.IndexOf(topMostChild);
return replicator.CurrentChildData[currentIndex];
}
}
Microsoft has a posted example of how to log to the Trace Log here.
So how does one use this in their application? The below code is how I plugged it into our SharePoint development framework. I’d love to hear how you are using it.
Step 1:
I modified the Microsoft’s TraceProvider’s RegisterTraceProvider and UnregisterTraceProvider methods as follows:
private static readonly object RegisterLock = new object();
private static bool isRegistered = false;
public static unsafe void RegisterTraceProvider()
{
lock (RegisterLock)
{
if (!isRegistered)
{
SPFarm farm = SPFarm.Local;
Guid traceGuid = farm.TraceSessionGuid;
uint result = NativeMethods.RegisterTraceGuids(ControlCallback, null,
ref traceGuid, 0, IntPtr.Zero, null, null, out hTraceReg);
System.Diagnostics.Debug.Assert(result == NativeMethods.ERROR_SUCCESS);
isRegistered = true;
}
}
}
public static void UnregisterTraceProvider()
{
lock (RegisterLock)
{
if (isRegistered)
{
uint result = NativeMethods.UnregisterTraceGuids(hTraceReg);
System.Diagnostics.Debug.Assert(result == NativeMethods.ERROR_SUCCESS);
isRegistered = false;
}
}
}Step 2:
I created our own TraceLogProvider object extending our BaseLogProvider which implements our custom ILogProvider interface. This provider object makes the appropriate calls into Microsoft’s TraceProvider, but now exposes a friendly logging interface to use within our application.
public class TraceLogProvider : BaseLogProvider, IDisposable
{
public string ApplicationName { get; set; }
public void Log(string msg, LogSeverity severity)
{
var traceSeverity = GetTraceSeverity(severity);
TraceProvider.RegisterTraceProvider();
string[] lines = msg.Split(new string[] { Environment.NewLine },
StringSplitOptions.RemoveEmptyEntries);
foreach (string line in lines)
{
TraceProvider.WriteTrace(0, traceSeverity, Guid.Empty, "Your Company Name",
ApplicationName, "General", line);
}
}
private TraceProvider.TraceSeverity GetTraceSeverity(LogSeverity severity)
{
switch (severity)
{
case LogSeverity.Info:
return TraceProvider.TraceSeverity.InformationEvent;
case LogSeverity.Warn:
return TraceProvider.TraceSeverity.WarningEvent;
default:
return TraceProvider.TraceSeverity.CriticalEvent;
}
}
#region IDisposable Members
public virtual void Dispose()
{
TraceProvider.UnregisterTraceProvider();
}
#endregion
}And for reference, our BaseLogProvider is shown below:
public abstract class BaseLogProvider : ILogProvider
{
#region ILogProvider Members
public virtual void Info(string msg)
{
Log(msg, LogSeverity.Info);
}
public virtual void Info(Exception e)
{
Log(e, LogSeverity.Info);
}
public virtual void Info(string msg, Exception e)
{
Log(msg, e, LogSeverity.Info);
}
public virtual void Warn(string msg)
{
Log(msg, LogSeverity.Warn);
}
public virtual void Warn(Exception e)
{
Log(e, LogSeverity.Warn);
}
public virtual void Warn(string msg, Exception e)
{
Log(msg, e, LogSeverity.Warn);
}
public virtual void Error(string msg)
{
Log(msg, LogSeverity.Error);
}
public virtual void Error(Exception e)
{
Log(e, LogSeverity.Error);
}
public virtual void Error(string msg, Exception e)
{
Log(msg, e, LogSeverity.Error);
}
public virtual void Log(Exception e, LogSeverity severity)
{
Log(FormatException(e), severity);
}
public virtual void Log(string msg, Exception e, LogSeverity severity)
{
Log(msg + "\n" + FormatException(e), severity);
}
public abstract void Log(string msg, LogSeverity severity);
#endregion
protected virtual string FormatException(Exception ex)
{
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.AppendLine(ex.ToString());
if (ex.InnerException != null)
{
stringBuilder.AppendLine(ex.InnerException.ToString());
if (ex.InnerException.InnerException != null)
{
stringBuilder.AppendLine(ex.InnerException.InnerException.ToString());
}
}
return stringBuilder.ToString();
}
}
public enum LogSeverity
{
Info,
Warn,
Error
}
Seeing this? The security validation for this page is invalid. I am sure this error has good intentions, but it is showing its face far too often. Hristo Pavlov has written a good explanation on AllowUnsafeUpdates here.
If you read my previous post and are attempting to update list items as the System User, you will likely run into this problem. Setting AllowUnsafeUpdates to true for the duration of the update has allowed me to get around this exception. Here is the helper method I am using to accomplish this:
public static void DoUnsafeUpdate(SPWeb web, Action action)
{
bool allowUnsafeUpdates = web.AllowUnsafeUpdates;
web.AllowUnsafeUpdates = true;
action();
web.AllowUnsafeUpdates = allowUnsafeUpdates;
}Couple this with the helper methods in my previous post, and you now can do both together:
public static void DoUnsafeUpdateAsSystemUser(SPWeb web, SPWebAction action)
{
DoAsSystemUser(web, delegate(SPWeb systemWeb)
{
DoUnsafeUpdate(systemWeb, delegate()
{
action(systemWeb);
});
});
}
Scenario
You are writing a custom web part or control and want to be able to access a list or resource within your code that the current user otherwise does not have permissions to. For me, this happens quite frequently. For example:
- Reading info from a list dedicated to storing Application Settings that only an administrator can read and edit
- Modifying permissions on a list item after creating it
- Modifying a list item other than the specific item in context
- Updating Web properties
- Kicking off a workflow from code as a result of a users action (event handlers are also a good place to do this, which already run under the context of the System user)
What Didn’t Work
SPSecurity.RunWithElevatedPriveleges - this only impersonates the user account running the thread in order to access network resources, etc. But if you are accessing SharePoint resources using the SPContext.Current.Web, your SPWeb object is still limited to the permission set of the original user initiating the request.
What Did Work
Create a new site using the Site.SystemAccount UserToken and then open the web using this Site. Here are two helper methods I am using for doing just this:
public delegate void SPWebAction(SPWeb web);
public static void DoAsSystemUser(SPWeb web, SPWebAction action)
{
SPUser systemUser = web.Site.SystemAccount;
DoAsUser(web, systemUser, action);
}
public static void DoAsUser(SPWeb web, SPUser user, SPWebAction action)
{
// If we are already running as the given User Token, just pass the web along
if (web.CurrentUser != null &&
web.CurrentUser.UserToken.CompareUser(user.UserToken))
{
action(web);
return;
}
using (SPSite site = new SPSite(web.Site.ID, user.UserToken))
{
using (SPWeb userWeb = site.OpenWeb(web.ID))
{
action(userWeb);
}
}
}Two more things that still need to be addressed are Security Validation and Unsafe Updates, which I will talk about in the next post.
So I just completed and released to production my first approval workflow application using ASP.Net forms and Visual Studio Workflow Designer. I have combed through hundreds of web pages working out many many kinks. These are the top 5 links for this month (measured on subjective scale of usefulness to me for completing my project):
Get Public Key Token Visual Studio Trick
SharePoint Workflow Basics
Design and Bind ASPX Forms to Workflow
Locked Workflow tasks Bug
WSS WebService DISCO and WSDL Generator
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