Question

My project requires me to programmatically access TFS servers we don’t administer and to get real time information about the fields in the WorkItemTypes. I can get the field names and most of the information I need by looking at the FieldDefinition in the WorkItemType’s FieldDefinitions collection.

    public WitType(WorkItemType type)
    {
        this.Fields = new List<string>();

        foreach (FieldDefinition f in type.FieldDefinitions)
        {
            Fields.Add(f.Name);
        }
    }

One thing missing is the IsRequired property. I need to be able to tell if a field is required.
I have tried running a work item story query

WorkItemCollection workItemCollection = workItemStore.Query
foreach (WorkItem workItem in workItemCollection)
foreach (Field field in workItem.Fields)
{
     textBox1.Text += field.Name + " is required? " +  field.IsRequired.ToString();                 
}

and then checking the IsRequired property of the Field item in the WorkItem’s Fields collection.
Only problem is that for a given work item type one work item says Title is required, then the next work item will have the IsRequired property = false.

Is there a way to determine if a WorkItem field is required without resorting to the WIT xml file? If not, is there a way to programmatically access the WIT xml file?

Answer 1

I needed to perform a similar task, and the following was the only way I could figure out how to accomplish it.

As mentioned by others, WorkItem validation is defined in the WorkItemType’s template. Fields can have different validation requirements based on the WorkItem’s current state and even the current user’s permissions.

Therefore, you need to create/retrieve a WorkItem instance using the user’s credentials. If your application is impersonating the current user (i.e. in an ASP.NET application using Windows Authentication and impersonation), then you can simply use Option 1, where you use the TFS API to get the WorkItem, without impersonating.

If you’re application is not impersonating the user, when you can use Option 2, where you use the TFS impersonation feature, to make calls on-behave of a user. This requires granting the “Make Requests on behave of others” permission in TFS to the application’s identity (i.e. in ASP.NET the application pool’s identity). See the following link for more information:
http://blogs.microsoft.co.il/blogs/shair/archive/2010/08/23/tfs-api-part-29-tfs-impersonation.aspx

The following code is an example on how to do Option 1 and Option 2.

        // Set the following variables accordingly
        string workItemTypeName = "Bug";
        string teamProjectName = "My Project";
        string usernameToImpersonate = "joesmith";
        string tfsTeamProjectCollectionUrl = "http://mydomain.com:8080/tfs/ProjectCollectionName";

        // OPTION 1: no impersonation.
        // Get an instance to TFS using the current thread's identity.
        // NOTE: The current thread's identity needs to have the "" permision or else you will receive
        //       a runtime SOAP exception: "Access Denied: [username] needs the following permission(s) to perform this action: Make requests on behalf of others"
        TfsTeamProjectCollection tfs = new TfsTeamProjectCollection( new Uri( tfsTeamProjectCollectionUrl ) );
        IIdentityManagementService identityManagementService = tfs.GetService<IIdentityManagementService>();

        // OPTION 2: impersonation.  Remove the following two lines of code if you don't need to impersonate.
        // Get an instance to TFS impersonating the specified user.
        // NOTE: This is not needed if the current thread's identity is that of the user 
        //       needed to impersonate. Simple use the ablve TfsTeamProjectCollection instance
        TeamFoundationIdentity identity = identityManagementService.ReadIdentity( IdentitySearchFactor.AccountName, usernameToImpersonate, MembershipQuery.None, ReadIdentityOptions.None );
        tfs = new TfsTeamProjectCollection( tfs.Uri, identity.Descriptor );

        WorkItem workItem = null;
        WorkItemStore store = tfs.GetService<WorkItemStore>();

        // Determine if we are creating a new WorkItem or loading an existing WorkItem.
        if( workItemId.HasValue ) {
           workItem = store.GetWorkItem( workItemId.Value );
        }
        else {
           Project project = store.Projects[ teamProjectName ];
           WorkItemType workItemType = project.WorkItemTypes[ workItemTypeName ];
           workItem = new WorkItem( workItemType );
        }

        if( workItem != null ) {

           foreach( Field field in workItem.Fields ) {
              if( field.IsRequired ) {
                 // TODO
              }
           }
        }