Programmatically List Existing Tags Using The TFS API

December 12, 2016

Having looked into this for some time; I came up with the following method of extracting team project tags. I’m not for a minute suggesting this is the best way of doing this - but it does work. My guess is that it’s not a very scalable solution, as it’s doing a LOT of work.

As it was, I couldn’t find a way to directly query the tags, so instead, I’m going through all the work items, and picking the tags. I couldn’t even find a way to filter the work items that actually have tags; so here’s the query that I ended up with:

private static IEnumerable<string> GetAllDistinctWorkItemTags(string uri, string projectName)
    TfsTeamProjectCollection tfs;
    tfs = TfsTeamProjectCollectionFactory.GetTeamProjectCollection(new Uri(uri)); //
    var wis = new WorkItemStore(tfs);
    WorkItemCollection workItemCollection = wis.Query(
         " SELECT [System.Tags]" +
         " FROM WorkItems " +
         $" WHERE [System.TeamProject] = '{projectName}' ");                
    if (workItemCollection.Count == 0)
        return null;
    List<string> tags = new List<string>();
    foreach (WorkItem wi in workItemCollection)
        if (string.IsNullOrWhiteSpace(wi.Tags)) continue;
        var splitTags = wi.Tags.Split(';');
    return tags.Distinct();

From debugging, I strongly suspect that whatever you put in the “SELECT”, it returns the entire work item. I also, for the life of me, couldn’t work out a lambda query for parsing the tags.

The calling method is here:

public static IEnumerable<string> GetAllTags(string uri, string teamProject)
    var project = GetTeamProject(uri, teamProject);
    IEnumerable<string> tags = GetAllDistinctWorkItemTags(uri, teamProject);
    return tags;

I’ve listed GetTeamProject helper method before, but for the sake of completeness:

public static Project GetTeamProject(string uri, string name)
    TfsTeamProjectCollection tfs;
    tfs = TfsTeamProjectCollectionFactory.GetTeamProjectCollection(new Uri(uri)); //
    var workItemStore = new WorkItemStore(tfs);
    var project = (from Project pr in workItemStore.Projects
                       where pr.Name == name
                       select pr).FirstOrDefault();
    if (project == null)
        throw new Exception($"Unable to find {name} in {uri}");
    return project;

Here’s the output:


Notes on Tags

A couple of points on tags: firstly, tags seem to exist in a kind of transient state; that is, while something is tagged, the tag exists, but once you remove all instances of a tag (for example, if I removed “Tagtest1” from all work items in my team project, TFS would eventually (I believe after a couple of days) just delete the tag for me. Obviously, in my example, as soon as I did this, I would no longer find it. This might leave you thinking that there is a more efficient way of removing tags (that is, you should be able to access the transient store in some way).

The existence of this Visual Studio plug-in lends support to that idea. It allows you to maintain the tags within your team project. If you’re using tags in any kind of serious way then I’d strongly recommend that you try it.


This is doing a lot of (IMO) unnecessary work, so I tried a little performance test; using this post as a template, I created a lot of bugs:


As you can see, I created a random set of tags. One other point that I’m going to put here is that a TFS database with ~30K work items and no code whatsoever increases the size of the default collection DB to around 2GB:


Now I ran the GetAllTags with some timing on:


19 seconds, which seems like quite a reasonable speed to me for 13.5k tags.

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