`Type.GetProperties` property order

Question

Short Version

The MSDN documentation for Type.GetProperties states that the collection it returns is not guaranteed to be in alphabetical or declara

Answer 1

1:

I've spent the last day troubleshooting a problem in an MVC 3 project, and it all came down to this particular problem. It basically relied on the property order being the same throughout the session, but on some occations a few of the properties switched places, messing up the site.

First the code called Type.GetProperties() to define column names in a dynamic jqGrid table, something that in this case occurs once per page_load. Subsequent times the Type.GetProperties() method was called was to populate the actual data for the table, and in some rare instances the properties switched places and messed up the presentation completely. In some instances other properties that the site relied upon for a hierarchical subgrid got switched, i.e. you could no longer see the sub data because the ID column contained erroneous data. In other words: yes, this can definitely happen. Beware.

2:

If you need consistent order throughout the system session but not nessecarily exactly the same order for all sessions the workaround is dead simple: store the PropertyInfo[] array you get from Type.GetProperties() as a value in the webcache or in a dictionary with the type (or typename) as the cache/dictionary key. Subsequently, whenever you're about to do a Type.GetProperties(), instead substitute it for HttpRuntime.Cache.Get(Type/Typename) or Dictionary.TryGetValue(Type/Typename, out PropertyInfo[]). In this way you'll be guaranteed to always get the order you encountered the first time.

If you always need the same order (i.e. for all system sessions) I suggest you combine the above approach with some type of configuration mechanism, i.e. specify the order in the web.config/app.config, sort the PropertyInfo[] array you get from Type.GetProperties() according to the specified order, and then store it in cache/static dictionary.