A few things you should know about CreateTaskWithContentType in SharePoint Workflow

Here are a few things that you should know when working with the CreateTaskWithContentType activity in a SharePoint workflow.

1)      If you don’t enable ContentTypes in the task list you’re get a null reference exception (from the activity itself, not your code.)

2)      The ContentType that you specify in the ContentType property isn’t automatically associated.  You’ll want to verify the content type exists in the _MethodInvoking() event.  You could call the code below to automatically enable content types and if necessary add the contentType:

        /// <summary>

        /// Verify — and if necessary modify — the task list to ensure that the required fields are available.

        /// </summary>

        /// <param name="taskList">The list to be verified</param>

        /// <param name="contentType">The content type id to add</param>

        public static void VerifyModifyTaskList(SPList taskList, string contentType)

        {

            try

            {

                SPContentTypeId contentTypeId = new SPContentTypeId(contentType);

 

                taskList.ContentTypesEnabled = true;

                SPContentTypeId matchContentTypeId = taskList.ContentTypes.BestMatch(contentTypeId);

 

                if (matchContentTypeId.Parent.CompareTo(contentTypeId) != 0)

                {

                    SPContentType ct = taskList.ParentWeb.AvailableContentTypes[contentTypeId];

                    taskList.ContentTypes.Add(ct);

                    taskList.Update();

 

                }

            }

            catch

            {

                throw;

            }

        }

3)      You can’t test for whether a content type is associated with a list or not by its “short” identifier directly.  You have to use the .BestMatch method as shown above to determine whether the content type is associated or not.

9 replies
  1. Jeroen Van Bastelaere
    Jeroen Van Bastelaere says:

    @Paul> No he doesn’t have to do that here, the SPList is handed down from another function and if you would dispose here you could end up killing the context (or smthing else, but still making the following code that uses that SPWeb crash)

    @Simon> This works fine for me, you might still have another problem

  2. Felipe Vale
    Felipe Vale says:

    It`s ok, there`s no errors in the code. But I`m still getting errors in the workflow execution at the creation of the taskWithContentType.

  3. Steve
    Steve says:

    Thanks for this useful tip

    Where is the best place to call this code ?

    I would say in the association page, but what about if I don’t have a specific association page?

    steve

  4. Wesley
    Wesley says:

    Thanks! Solved my three day journey down to the SPOETaskService(or somthing like that..) I HATE it when error messages suck!

  5. Radheshyam Mali
    Radheshyam Mali says:

    public static void VerifyModifyTaskList(SPList taskList, string contentType)

    {

    try

    {

    SPContentTypeId contentTypeId = new SPContentTypeId(contentType);

    taskList.ContentTypesEnabled = true;

    SPContentTypeId matchContentTypeId = taskList.ContentTypes.BestMatch(contentTypeId);

    if (matchContentTypeId.Parent.CompareTo(contentTypeId) != 0)

    {

    SPContentType ct = taskList.ParentWeb.AvailableContentTypes[contentTypeId];

    taskList.ContentTypes.Add(ct); ERRO—–get a null reference exception ———-

    taskList.Update();

    }

    }

    catch

    {

    throw;

    }

    }

    Can u help me anybody? Thank you very much.

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