If you track your project tasks against work items, you would know the importance of Work Item History. This is one way for you to reflect on who did what and when, some organizations use it for auditing purposes as well. Using the WorkItemStore service, it is possible to get the work item revisions, now depending on how creative you are, you can plot the data and visualize the changes as you like.

In this blog post I'll be showing you,

How to get the work item history programmatically using TFS API
Display the work item history programmatically in a data grid

A screen shot of what we are after:

1. Get the Work Item Details Programmatically using TFS API

I’ll start simple. Pass a work item id to get the work item details.

public WorkItem GetWorkItemDetails(int id)
{
    var tfs =
    TfsTeamProjectCollectionFactory.GetTeamProjectCollection(
    new Uri("https://tfs2010:8080/defaultcollection"));
    var service = tfs.GetService<WorkItemStore>();

    return service.GetWorkItem(id);
}

The above code will return the WorkItem object, we will be interested in the property “Revisions” - Gets a RevisionCollection object that represents a collection of valid revision numbers for this work item.

2. Get the Work Item Revision ‘History’ Programmatically using TFS API

Now it is very important to understand that the revision history can only be retrieved for work item fields available in the collection WorkItem.Fields, so if you used the below code to get the workitem revision history, you will NOT see the history, but end up reloading the current workitem object again and again.

// Returns a work item object
var wi = GetWorkItemDetails(299);

// This will NOT give you work item history
// will only loop through revisions and
// actually not load the work item history
// but will load the latest work item revision
// again and again
foreach (Revision revision in wi.Revisions)
{
    Debug.Write(revision.WorkItem);
}

Let’s have a look at the Fields property in the WorkItem object:

// Work Item fields for which we can get history
foreach (Field field in wi.Fields)
{
    Debug.Write(String.Format("{0}{1}", field.Name, Environment.NewLine));
}

Output

Title
State
Authorized Date
Watermark
Rev
Changed By
Backlog Priority
Integration Build
Description HTML
Reason
Iteration Path
Iteration ID
Assigned To
Work Item Type
Effort
Acceptance Criteria
Created Date
Created By
Business Value
Description
History
External Link Count
Related Link Count
Team Project
Hyperlink Count
Attached File Count
Node Name
Area Path
Revised Date
Changed Date
ID
Area ID
Authorized As

So, it is safe to use the below code to get the work item history using the TFS API programmatically,

// Returns a work item object
var wi = GetWorkItemDetails(299);

// Get All work item revisions
foreach (Revision revision in wi.Revisions)
{
    // Get value of fields in the work item revision
    foreach (Field field in wi.Fields)
    {
        Debug.Write(revision.Fields[field.Name].Value);
    }
}

Let's see the output now:

Revision[0]: Title - This is a test PBI 1
Revision[0]: State - New
Revision[0]: Authorized Date - 08/08/2011 22:18:24
Revision[0]: Watermark - 1
Revision[0]: Rev - 1
Revision[0]: Changed By - arora.tarun@hotmail.com
Revision[0]: Backlog Priority - 1000
Revision[0]: Integration Build -
Revision[0]: Description HTML - As a &lt;type of user&gt;
I want &lt;some goal&gt; so that &lt;some reason&gt;
Revision[0]: Reason - New backlog item
Revision[0]: Iteration Path - Temp_UK_1
Revision[0]: Iteration ID - 161
Revision[0]: Assigned To - arora.tarun@hotmail.com
Revision[0]: Work Item Type - Product Backlog Item
Revision[0]: Effort - 100
Revision[0]: Acceptance Criteria -
Revision[0]: Created Date - 08/08/2011 22:18:24
Revision[0]: Created By - arora.tarun@hotmail.com
Revision[0]: Business Value - 1000
Revision[0]: Description -
Revision[0]: History -
Revision[0]: External Link Count - 0
Revision[0]: Related Link Count - 0
Revision[0]: Team Project - Temp_UK_1
Revision[0]: Hyperlink Count - 0
Revision[0]: Attached File Count - 0
Revision[0]: Node Name - Functional
Revision[0]: Area Path - Temp_UK_1\Functional
Revision[0]: Revised Date - 08/08/2011 22:18:42
Revision[0]: Changed Date - 08/08/2011 22:18:24
Revision[0]: ID - 299
Revision[0]: Area ID - 165
Revision[0]: Authorized As - arora.tarun@hotmail.com
Revision[1]: Title - This is a test PBI 1
Revision[1]: State - Approved
Revision[1]: Changed Date - 08/08/2011 22:18:42
…
Revision[2]: Changed Date - 08/08/2011 22:18:50
<a href="http://geekswithblogs.net/TarunArora/archive/2011/08/21/mailto:arora.tarun@hotmail.com%E2%80%A6Revision[3">…
Revision[3</a>]: Changed Date - 08/08/2011 22:18:57
…
Revision[4]: Changed Date - 14/08/2011 22:53:43
…
Revision[5]: Changed Date - 14/08/2011 23:00:41
…

Revision[6]: Title - This is a test PBI 1 - 2 - 3
Revision[6]: State - Done
Revision[6]: Authorized Date - 14/08/2011 23:00:49
Revision[6]: Changed By - arora.tarun@hotmail.com
Revision[6]: Backlog Priority - 1000
Revision[6]: Integration Build -
Revision[6]: Description HTML - <P>Whats up ? Hello World</P>
Revision[6]: Reason - Work finished
Revision[6]: Iteration Path - Temp_UK_1
Revision[6]: Assigned To - arora.tarun@hotmail.com
Revision[6]: Work Item Type - Product Backlog Item
Revision[6]: Revised Date - 01/01/9999 00:00:00
Revision[6]: Changed Date - 14/08/2011 23:00:49
Revision[6]: Authorized As - arora.tarun@hotmail.com

3. Putting Everything Together

Let's get the work item history and display the results through a datagrid:

/// <summary>
/// This method takes a work item id, generates a datatable with all revision fields.
/// </summary>
public void GetWorkItemHistory()
{
    var tfs =
    TfsTeamProjectCollectionFactory.GetTeamProjectCollection(
    new Uri("https://tfs2010:8080/defaultcollection"));
    var service = tfs.GetService<WorkItemStore>();

    var wi = service.GetWorkItem(299);

    var dataTable = new DataTable();

    foreach (Field field in wi.Fields)
    {
        dataTable.Columns.Add(field.Name);
    }

    foreach (Revision revision in wi.Revisions)
    {
        var row = dataTable.NewRow();
        foreach (Field field in wi.Fields)
        {
            row[field.Name] = revision.Fields[field.Name].Value;
        }
        dataTable.Rows.Add(row);
    }

    dgWiHistory.DataSource = dataTable;
    dgWiHistory.Width = 1000;
    dgWiHistory.Height = 600;
    dgWiHistory.AutoGenerateColumns = true;
}

4. Next Step - Visualize Work Item History

Let’s take this a step forward and do some visualization, I'll keep it simple by printing the results to the output window, but you can take this a step forward by printing the output to some visually attractive controls.

/// <summary>
/// This method takes a work item id, generates a datatable with all revision fields.
/// Then goes through a comparison algorithm to determine the diff between the 2 rows.
/// </summary>
public void VisualiseWorkItemHistory()
{
    // Connect to TFS
    var tfs =
        TfsTeamProjectCollectionFactory.GetTeamProjectCollection(
            new Uri("https://tfs2010:8080/defaultcollection"));
    
    // Get the work item store service
    var service = tfs.GetService<WorkItemStore>();
    
    // Get the work item details
    var wi = service.GetWorkItem(299);
    
    var dataTable = new DataTable();
    
    foreach (Field field in wi.Fields)
    {
        dataTable.Columns.Add(field.Name);
    }
    
    // Loop through the work item revisions
    foreach (Revision revision in wi.Revisions)
    {
        // Get values for the work item fields for each revision
        var row = dataTable.NewRow();
        foreach (Field field in wi.Fields)
        {
            row[field.Name] = revision.Fields[field.Name].Value;
        }
        dataTable.Rows.Add(row);
    }
    
    // Add the revision data to a datagrid
    dgWiHistory.DataSource = dataTable;
    dgWiHistory.Width = 1000;
    dgWiHistory.Height = 600;
    dgWiHistory.AutoGenerateColumns = true;
    
    // List of fields to ignore in comparison
    var visualize = new List<string>() 
    { "Title", "State", "Rev", 
    "Reason", "Iteration Path", 
    "Assigned To", "Effort", "Area Path" };
    
    
    Debug.Write(String.Format("Work Item: {0}{1}", wi.Id, Environment.NewLine));
    
    // Compare Two Work Item Revisions 
    for (int i = 0; i < dgWiHistory.RowCount; i++)
    {
        var currentRow = dgWiHistory.Rows[i];
        
        if (i + 1 < dgWiHistory.RowCount)
        {
            var currentRowPlus1 = dgWiHistory.Rows[i + 1];
            
            Debug.Write(String.Format("Comparing Revision {0} to {1} {2}", 
            i, i + 1, Environment.NewLine));
            
            bool title = false;
            
            for (int j = 0; j < currentRow.Cells.Count; j++)
            {
                if(!title)
                {
                    Debug.Write(
                        String.Format(String.Format
                        ("Changed By '{0}' On '{1}'{2}", 
                        currentRow.Cells["Changed By"].Value, 
                        currentRow.Cells["Changed Date"].Value, Environment.NewLine)));
                    title = true;
                }
                
                if (visualize.Contains(dataTable.Columns[j].ColumnName))
                {
                    if (currentRow.Cells[j].Value.ToString() 
                    != currentRowPlus1.Cells[j].Value.ToString())
                    {
                        Debug.Write(String.Format("[{0}]: '{1}' => '{2}' {3}", 
                                    dataTable.Columns[j].ColumnName, 
                                    currentRow.Cells[j].Value, currentRowPlus1.Cells[j].Value, 
                                    Environment.NewLine));
                    }
                }
            }
        }
    }
}

Output

Work Item: 299

Comparing Revision 1 to 2
Changed By 'arora.tarun@hotmail.com' On '08/08/2011 22:18:24'
[State]: 'New' => 'Approved'
[Reason]: 'New backlog item' => 'Approved by the Product Owner'

Comparing Revision 2 to 3
Changed By 'arora.tarun@hotmail.com' On '08/08/2011 22:18:42'
[State]: 'Approved' => 'Committed'
[Reason]: 'Approved by the Product Owner' => 'Commitment made by the team'

Comparing Revision 3 to 4
Changed By 'arora.tarun@hotmail.com' On '08/08/2011 22:18:50'
[State]: 'Committed' => 'Done'
[Reason]: 'Commitment made by the team' => 'Work finished'

Comparing Revision 4 to 5
Changed By 'arora.tarun@hotmail.com' On '08/08/2011 22:18:57'

Comparing Revision 5 to 6
Changed By 'arora.tarun@hotmail.com' On '14/08/2011 22:53:43'
[Title]: 'This is a test PBI 1' => 'This is a test PBI 1 - 2 - 3'

Comparing Revision 6 to 7
Changed By 'arora.tarun@hotmail.com' On '14/08/2011 23:00:41'

Thoughts, questions, feedback, suggestions, please feel free to add a comment.

TFS SDK: Work Item History Visualizer using TFS API