Question

I want to compare two objects of different versions and display their differences in UI.

First I call a method to know if there is any difference between the two objects

The method is:

public bool AreEqual(object object1,object object2, Type comparisionType) 

If the above method returns true, I call the GetDifferences method to get the differences which is:

public ObjectDifference[] GetObjectDifferences(object object1, object object2, Type comparisionType) {   ArrayList memberList = new ArrayList();   ArrayList differences = new ArrayList();    memberList.AddRange(comparisionType.GetProperties());   memberList.AddRange(comparisionType.GetFields());    for (int loopCount = 0; loopCount < memberList.Count; loopCount++)   {     object objVal1 = null;     object objVal2 = null;     MemberInfo member = ((MemberInfo)memberList[loopCount]);     switch (((MemberInfo)memberList[loopCount]).MemberType)     {       case MemberTypes.Field:         objVal1 = object1 != null ? ((FieldInfo)memberList[loopCount]).GetValue(object1) : null;         objVal2 = object2 != null ? ((FieldInfo)memberList[loopCount]).GetValue(object2) : null;         break;       case MemberTypes.Property:          objVal1 = object1 != null ? ((PropertyInfo)memberList[loopCount]).GetValue(object1, null) : null;         objVal2 = object2 != null ? ((PropertyInfo)memberList[loopCount]).GetValue(object2, null) : null;         break;       default:         break;     }      if (AreValuesDifferentForNull(objVal1, objVal2))     {       ObjectDifference obj = new ObjectDifference(objVal1, objVal2, member, member.Name);       differences.Add(obj);     }     else if (AreValuesDifferentForPrimitives(objVal1, objVal2))     {       ObjectDifference obj = new ObjectDifference(objVal1, objVal2, member, member.Name);       differences.Add(obj);     }     else if (AreValuesDifferentForList(objVal1, objVal2))     {       ObjectDifference[] listDifference = GetListDifferences((ICollection)objVal1, (ICollection)objVal2, member);       differences.AddRange(listDifference);     }     else if ((!AreValuesEqual(objVal1, objVal2)) && (objVal1 != null || objVal2 != null))     {       ObjectDifference obj = new ObjectDifference(objVal1, objVal2, member, member.Name);       differences.Add(obj);     }   }   return (ObjectDifference[])differences.ToArray(typeof(ObjectDifference)); }   public class ObjectDifference {   private readonly object objectValue1;   private readonly object objectValue2;   private readonly System.Reflection.MemberInfo member;   private readonly string description;    public object ObjectValue1   {     get { return objectValue1; }   }   public object ObjectValue2   {     get { return objectValue2; }   }   public System.Reflection.MemberInfo Member   {     get { return member; }   }   public string Description   {     get { return description; }   }    public ObjectDifference(object objVal1, object objVal2, System.Reflection.MemberInfo member, string description)   {     this.objectValue1 = objVal1;     this.objectValue2 = objVal2;     this.member = member;     this.description = description;   } } 

For each difference I create an object of type ObjectDifference and add it to the array. The highlighted portion is the one where I am stuck! If the object contains another complex object, My program does give me the differences but I dont know which type it belonged to

For example, I have two objects of type Name

class Name {   string firstName, LastName;   List phNumber; }  class PhoneNumber {   string officeNo, MobileNo, HomeNo; } 

while comparing two objects the output I get is plain –

• firstname – John Mary
• LastName – cooper Lor
• officeNo – 22222 44444
• MobileNo – 989898 089089
• HomeNo – 4242 43535

The Hierarchy that officeNo is of type PhoneNumber is lost, which is important for me to display.

How should I maintain this type of tree while creating differences? Hope I am able to make my problem understood.

Answer 1

What you are trying to do and display is inherently complex. I’ve done this in the past (for diffgram/delta-based processes), and even trying to display nested changes in a simple and friendly way is tricky.

If it fits your user-base, one option might be to simply serialize the two graphs as xml, and use something like xml diff.