Saturday, October 08, 2011

XmlSerializer and Implemented Interfaces

Here’s the scenario:

  1. Get some data from calls to a third-party API.
  2. Serialize that data to XML.
  3. Use XSLT to Transform that XML into a common set of classes.

The API utilizes Interfaces for all the objects it returns and it would have been nice if I could have simply used either XmlSerializer or DataContractSerializer on the objects I received, but of course nothing is simple. Suffice it to say that it doesn’t work, for either serializer.

So, I’ve spent the last day or two working on implementing my own classes from the various third-party Interfaces for the objects I need. Basically, I’ll be using the API to get some data. Then I’ll have to copy the data into my own classes and then serialize it to XML.

Theoretically, creating classes that implement on Interface should be easy (simply right-click on the Interface and choose “Implement Interface”. But, nooooo … even though I’m using Visual Studio 2010, it still generates properties the same way it did before the “invention” of automatic properties. In other words, instead of generating a property like this:

public int VehicleID { get; set; }

The property gets generated like this:

public int VehicleID
        throw new NotImplementedException();
        throw new NotImplementedException();

When you’re talking about implementing a ton of properties, you don’t want to have to fix each of these manually. I knew I could find a way to generate these Interface properties differently, but I had forgotten all about code snippets. Had the old “slap on the forehead” moment when I read this blog post, written by Daniel Cazzulino, about how to do this:

Duh! Why hadn’t I remembered how to do that myself? Gettin’ old I guess. =0(

But wait, there’s more. Some of these Interface properties did NOT have setters and so they get generated with only the get. While this doesn’t cause a problem with DataContractSerializer, the XmlSerializer will not work unless you have both getters and setters. Daniel mentions, in an update at the end of his blog post, how to take care of this, by producing private setters for the generated property:

public int IncidentID { get; private set; }

Unfortunately, because I’m copying data to my own classes, my class needs to have a public setter. In my case, this doesn’t really matter as far as the functionality of these classes, because I’m only using them so I can serialize the data to XML, so I don’t care that the “set” is exposed publicly.

The two serializers produce very different XML. The task I will tackle next week is to see if that matters when I use that XML for my XSLT Transformations. For those interested, I’ll probably post the results of what happens with that little experiment next week.