Using Mvc 4 Display Modes for Feature Toggles

It occurred to me that it's possible to use the new Mvc 4 feature Display Mode (meant for switching views for mobile versions) as a complement for Feature Toggles.

Obviously this can only switch out an entire view (or partial view) but it can be a nice alternative to putting lots of @if(featureEnabled) {} tags through your view.

Add the following code to your global.asax Application_Start (or create an App_Start module).

 DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("{NameOfFeature}")
{
     ContextCondition = (context => {true/false logic})
});

Then create 2 views - one for the feature being disabled and one for it being enabled - eg Index.cshtml and Index.{NameOfFeature}.cshtml.

This could also be used for similar concepts like permissions and a/b testing.

Tfs Extensibility - Automatically Create Code Reviews on Checkin

I created a small plugin that has a percentage chance to create code review requests on checkin. You could enhance this pretty easily to create reviews using a more complex condition (based on how long its been since they last had a review, or the size of the checkin etc) however I've found the 5% rule to be fairly successful mainly because people have gotten used to the review feature and have started requesting code reviews manually for things they feel are important.

The major gotcha I found while coding this was the need to impersonate the user performing the checkin as the creator is the only user who can close the review (which isn't very useful when its the service account).

	using Microsoft.TeamFoundation.Client;
	using Microsoft.TeamFoundation.Framework.Client;
	using Microsoft.TeamFoundation.Framework.Common;
	using Microsoft.TeamFoundation.Framework.Server;
	using Microsoft.TeamFoundation.WorkItemTracking.Client;
	using System;
	using System.Collections.Generic;
	using System.IO;
	using System.Linq;
	using System.Text;
	namespace Enlighten.Tfs.Subscribers.CodeReviewCreator
	{
	public class CodeReviewCreator : ISubscriber
	{
	public string Name
	{
	get { return "Automated Code Review Creation"; }
	}
	public SubscriberPriority Priority
	{
	get { return SubscriberPriority.Normal; }
	}
	public EventNotificationStatus ProcessEvent(TeamFoundationRequestContext requestContext, NotificationType notificationType, object notificationEventArgs, out int statusCode, out string statusMessage, out Microsoft.TeamFoundation.Common.ExceptionPropertyCollection properties)
	{
	statusCode = 0;
	statusMessage = string.Empty;
	properties = null;
	try
	{
	if (notificationType == NotificationType.Notification && notificationEventArgs is Microsoft.TeamFoundation.VersionControl.Server.CheckinNotification)
	{
	var checkinNotification = notificationEventArgs as Microsoft.TeamFoundation.VersionControl.Server.CheckinNotification;
	//5% chance to create code review - probably want something a bit more complex
	if ((new Random()).NextDouble() <= 0.05)
	{
	TeamFoundationLocationService service = requestContext.GetService<TeamFoundationLocationService>();
	Uri selfReferenceUri = service.GetSelfReferenceUri(requestContext, service.GetDefaultAccessMapping(requestContext));
	TfsTeamProjectCollection tfsTeamProjectCollection = new TfsTeamProjectCollection(selfReferenceUri);
	// Look up the user that we want to impersonate
	IIdentityManagementService identityManagementService = tfsTeamProjectCollection.GetService<IIdentityManagementService>();
	Microsoft.TeamFoundation.Framework.Client.TeamFoundationIdentity identity = identityManagementService.ReadIdentity(IdentitySearchFactor.AccountName, checkinNotification.ChangesetOwner.UniqueName, MembershipQuery.None, ReadIdentityOptions.None);
	TfsTeamProjectCollection impersonatedCollection = new TfsTeamProjectCollection(tfsTeamProjectCollection.Uri, identity.Descriptor);
	var workitemStore = impersonatedCollection.GetService<WorkItemStore>();
	var project = workitemStore.Projects["Enlighten"]; //todo get project name from checkinNotification.GetSubmittedItems()
	var type = project.WorkItemTypes["Code Review Response"];
	var workItem = new WorkItem(type) { Title = checkinNotification.Comment };
	workItem.Fields["System.AssignedTo"].Value = "Betty"; //todo pick someone better
	workItem.Fields["System.State"].Value = "Requested";
	workItem.Fields["System.Reason"].Value = "New";
	var result = workItem.Validate();
	foreach (Field item in result)
	{
	//insert some form of logging here
	}
	workItem.Save();
	var responseId = workItem.Id;
	type = project.WorkItemTypes["Code Review Request"];
	workItem = new WorkItem(type) { Title = checkinNotification.Comment };
	workItem.Fields["System.AssignedTo"].Value = checkinNotification.ChangesetOwner.DisplayName;
	workItem.Fields["Microsoft.VSTS.CodeReview.ContextType"].Value = "Changeset";
	workItem.Fields["Microsoft.VSTS.CodeReview.Context"].Value = checkinNotification.Changeset;
	workItem.Fields["System.AreaPath"].Value = project.Name; //todo they're put into root of project, may want a better location from source path
	workItem.Fields["System.IterationPath"].Value = project.Name;
	workItem.Fields["System.State"].Value = "Requested";
	workItem.Fields["System.Reason"].Value = "New";
	WorkItemLinkTypeEnd linkTypeEnd = workitemStore.WorkItemLinkTypes.LinkTypeEnds["Child"];
	workItem.Links.Add(new RelatedLink(linkTypeEnd, responseId));
	//todo copy related workitems from the checkin
	result = workItem.Validate();
	foreach (Field item in result)
	{
	//insert some form of logging here
	}
	workItem.Save();
	}
	}
	}
	catch (Exception e)
	{
	//insert some form of logging here
	}
	return EventNotificationStatus.ActionPermitted;
	}
	public Type[] SubscribedTypes()
	{
	return new Type[] { typeof(Microsoft.TeamFoundation.VersionControl.Server.CheckinNotification) };
	}
	}
	}

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