March 2008 Archives

Hi everyone, sorry I haven't completed writing about my Plugin system, but I did successfully find a solution to my issues, and created a flexible system which works very well.  I'll get more into that later, but I'm very happy with it and am not able to quickly create plugins of different types and use them within my applications.  The database code is so utterly simple [ I wrote 3 different database plugins, for MySQL/SQL Server/MS Access ] to use:

using(IDatabase dbObj = Plugin.Database()) { string s = String.Empty; foreach(tbl_myTable myTableObj in dbObj.Query<tbl_myTable>("SELECT * FROM myTable")) { // Do something with myTableObj s += myTableObj.name + Environment.NewLine; } MessageBox.Show(s); } // WOW! That's easy


However, that's not what the subject of this article is!  I needed a quick and easy way to copy objects of differing types to one another, as long as they have matching fields.  An example would be a base class, to a derived class of similar type.. but they're different, so you can't just do a direct assignment!  Here is the code:

/// <summary> /// Copy an object to destination object, only matching fields will be copied /// </summary> /// <typeparam name="T"></typeparam> /// <param name="sourceObject">An object with matching fields of the destination object</param> /// <param name="destObject">Destination object, must already be created</param> public void CopyObject<T>(object sourceObject, ref T destObject) { // If either the source, or destination is null, return if (sourceObject == null || destObject == null) return; // Get the type of each object Type sourceType = sourceObject.GetType(); Type targetType = destObject.GetType(); // Loop through the source properties foreach (PropertyInfo p in sourceType.GetProperties()) { // Get the matching property in the destination object PropertyInfo targetObj = targetType.GetProperty(p.Name); // If there is none, skip if (targetObj == null) continue; // Set the value in the destination targetObj.SetValue(destObject, p.GetValue(sourceObject,null), null); } }

Usage:
tbl_myTable source = new tbl_myTable();
tbl_myTableDerived dest = new tbl_myTableDerived();
source.name = "Joe";

CopyObject(source, dest);

MessageBox.Show(dest.name); // "Joe";

Only fieldnames that are equal in both classes will be copied.  For thoroughness, it would be better to make sure the types are also equal -- but I don't need to go through the hassle of that, in my scenarios the field types and names will be equal.  YMMV.

Thank you!  I hope someone finds this very useful.

- Matthew MacSuga