Gary's Blog

In a previous post, on cloning objects in XAF, I showed you how to use the Clone Module. Of course, this solution only works if there is user interaction. What if you want to do this programmatically? Well, given the following business class:

using System;
using DevExpress.Xpo;

namespace SimpleObject {
    public class Parent : XPObject {
        public Parent(Session session) : base(session) { }
        public override void AfterConstruction() {
            base.AfterConstruction();
        }

        private string _Name;
        public string Name {
            get {
                return _Name;
            }
            set {
                SetPropertyValue("Name", ref _Name, value);
            }
        }

        [Association("ParentChildren"), Aggregated]
        public XPCollection<Child> Children {
            get { return GetCollection<Child>("Children"); }
        }
    }

    public class Child : XPObject {
        public Child(Session session) : base(session) { }
        public override void AfterConstruction() {
            base.AfterConstruction();
        }

        private string _Name;
        public string Name {
            get {
                return _Name;
            }
            set {
                SetPropertyValue("Name", ref _Name, value);
            }
        }

        private Parent _Parent;
        [Association("ParentChildren")]
        public Parent Parent {
            get {
                return _Parent;
            }
            set {
                SetPropertyValue("Parent", ref _Parent, value);
            }
        }
    }
}

And the following helper class:

using System;
using DevExpress.Xpo;
using System.Collections.Generic;
using DevExpress.Xpo.Metadata;
using System.Collections;

namespace SimpleObject {
    public class CloneIXPSimpleObjectHelper {
        /// <summary>
        /// A dictionary containing objects from the source session as key and objects from the 
        /// target session as values
        /// </summary>
        /// <returns></returns>
        Dictionary<object, object> clonedObjects;
        Session sourceSession;
        Session targetSession;

        /// <summary>
        /// Initializes a new instance of the CloneIXPSimpleObjectHelper class.
        /// </summary>
        public CloneIXPSimpleObjectHelper(Session source, Session target) {
            this.clonedObjects = new Dictionary<object, object>();
            this.sourceSession = source;
            this.targetSession = target;
        }

        public T Clone<T>(T source) where T : IXPSimpleObject {
            return Clone<T>(source, targetSession, false);
        }
        public T Clone<T>(T source, bool synchronize) where T : IXPSimpleObject {
            return (T)Clone(source as IXPSimpleObject, targetSession, synchronize);
        }

        public object Clone(IXPSimpleObject source) {
            return Clone(source, targetSession, false);
        }
        public object Clone(IXPSimpleObject source, bool synchronize) {
            return Clone(source, targetSession, synchronize);
        }

        public T Clone<T>(T source, Session targetSession, bool synchronize) where T : IXPSimpleObject {
            return (T)Clone(source as IXPSimpleObject, targetSession, synchronize);
        }

        /// <summary>
        /// Clones and / or synchronizes the given IXPSimpleObject.
        /// </summary>
        /// <param name="source"></param>
        /// <param name="targetSession"></param>
        /// <param name="synchronize">If set to true, reference properties are only cloned in case
        /// the reference object does not exist in the targetsession. Otherwise the exising object will be
        /// reused and synchronized with the source. Set this property to false when knowing at forehand 
        /// that the targetSession will not contain any of the objects of the source.</param>
        /// <returns></returns>
        public object Clone(IXPSimpleObject source, Session targetSession, bool synchronize) {
            if (source == null)
                return null;
            if (clonedObjects.ContainsKey(source))
                return clonedObjects[source];
            XPClassInfo targetClassInfo = targetSession.GetClassInfo(source.GetType());
            object clone = null;
            if (synchronize)
                clone = targetSession.GetObjectByKey(targetClassInfo, source.Session.GetKeyValue(source));
            if (clone == null)
                clone = targetClassInfo.CreateNewObject(targetSession);
            clonedObjects.Add(source, clone);

            foreach (XPMemberInfo m in targetClassInfo.PersistentProperties) {
                if (m is DevExpress.Xpo.Metadata.Helpers.ServiceField || m.IsKey)
                    continue;
                object val;
                if (m.ReferenceType != null) {
                    object createdByClone = m.GetValue(clone);
                    if ((createdByClone != null) && synchronize == false)
                        val = createdByClone;
                    else {
                        val = Clone((IXPSimpleObject)m.GetValue(source), targetSession, synchronize);
                    }

                }
                else {
                    val = m.GetValue(source);
                }
                m.SetValue(clone, val);
            }
            foreach (XPMemberInfo m in targetClassInfo.CollectionProperties) {
                if (m.HasAttribute(typeof(AggregatedAttribute))) {
                    XPBaseCollection col = (XPBaseCollection)m.GetValue(clone);
                    XPBaseCollection colSource = (XPBaseCollection)m.GetValue(source);
                    foreach (IXPSimpleObject obj in new ArrayList(colSource))
                        col.BaseAdd(Clone(obj, targetSession, synchronize));
                }
            }
            return clone;
        }
    }
}

Then cloning can be performed using the following code:

private void Form1_Load(object sender, System.EventArgs e) {
     UnitOfWork uow1 = new UnitOfWork();
     Parent obj = new Parent(uow1);
     obj.Name = "Parent A";
     Child ch1 = new Child(uow1);
     ch1.Name = "Child 1";

     Child ch2 = new Child(uow1);
     ch2.Name = "Child 2";

     obj.Children.Add(ch1);
     obj.Children.Add(ch2);
     obj.Save();
     uow1.CommitChanges();

     listBox1.Items.Add(string.Format("Object created: {0}", obj.Name));

     UnitOfWork uow2 = new UnitOfWork();
     CloneIXPSimpleObjectHelper cloneHelper = new CloneIXPSimpleObjectHelper(uow1, uow2);
     Parent clone = cloneHelper.Clone(obj) as Parent;

     listBox1.Items.Add(string.Format("Object cloned: {0}", clone.Name));
     listBox1.Items.Add(string.Format("Object's child 1: {0}", clone.Children[0].Name));
     listBox1.Items.Add(string.Format("Object's child 2: {0}", clone.Children[1].Name));
 }