XML Data file versioning

[Chris_Collier]

I'm building an application (which I am intending to share at a local user group soon), but am having issues with XML file data versioning.

 

My intent is to have a data type which has a version string, and a variant for the data which will be read according to the version number in the version string.  The issue is that if you flatten the data type to an XML string with any data in the variant, then try to unflatten the data, you get an error (1106: "LabVIEW:  The XML tag describing the type of data does not match the wired type.")

 

How have you done versioning for data files which you are pretty sure will change over time?

 

And can anyone tell me why this attempt doesn't work?

 

Thanks,

 

-Chris Collier

 

P.S. The attached files are in LV 2014

Test XML.zip

Edited August 20, 2015 by Chris_Collier

[ensegre]

And can anyone tell me why this attempt doesn't work?

 

Apparently, xml for an empty variant is different than that for a variant with some typed data content; you can circumvent that flattening the variant:

[Chris_Collier]

Thank you.  Implementing this does make the software work as I would expect.  This is more steps than I thought would or should be needed, but it should allow me to use versioning implemented as I wanted.

 

Thank you for your help!

[smithd]

The lavag json library (https://lavag.org/topic/16217-cr-json-labview/) is pretty good and seems to have the capability to avoid issues like this. If you need XML, GXML and jki easyxml would probably also handle the variant (although I haven't tried it which I have with the json library).

[Chris_Collier]

Since this is for a presentation at a User Group meeting, I wanted to keep as much of the code to standard LabVIEW install as possible (for those who inherently dislike plugin tools for whatever reason).  This should make it so that anyone with the correct version of LabVIEW will be able to review the code off-the-shelf.

That being said, I think I'll look into the JSON package for my own work.  Thanks for the link!