How to Deserialize and Serialize Build Process Parameters in TFS

Question

I am trying to create a new build definition using TFS 2013 API. The process template that I have to refer contains several custom activities and parameters. While creating the Build Definition, some of the Property value needs to be updated dynamically. So I tried to Deserialize the process parameters using below code:

IDictionary<string, object> processParams = WorkflowHelpers.DeserializeProcessParameters(defaultTemplate.Parameters);

This code always throwing below exception:

An unhandled exception of type 'System.Xaml.XamlObjectWriterException' occurred in System.Xaml.dll

Additional information: No matching constructor found on type 'System.Activities.Activity'. You can use the Arguments or FactoryMethod directives to construct this type.

This is really frustrating and I can't get rid of this error yet.

I have also tried to deserialize the process parameters using below code:

using (StringReader stringReader = new StringReader(parameterValues))
{
    object obj = XamlServices.Load(
          ActivityXamlServices.CreateReader(
              new XamlXmlReader((TextReader)stringReader, new XamlXmlReaderSettings { LocalAssembly  = System.Reflection.Assembly.GetExecutingAssembly() }
    )));
}

This works but when I serialize it again using XamlServices.Save(XamlWriter writer, object instance) method, the parameters got changed which is not compatible with build workflow.

So, how can I update the build process parameters here ? Can the WorkflowHelpers class can be used in other ways ? Or is there any other way to update the process parameters so that it gets reflected in the build definition. Any help is highly appreciated.

Answer 1

This is working fine now. Below is new code:

IDictionary<string, object> processParams = WorkflowHelpers.DeserializeProcessParameters(defaultTemplate.ProcessParameters);

Instead of defaultTemplate.Parameters, I need to pass defaultTemplate.ProcessParameters