Compare Objects for Any Change in Value

Introduction

Object comparison has always been a topic of debate. There are lot of ways to implement it, using comparer interface and implementing it, etc. But there is no generic way by which two similar objects of any type/class can be compared for the change in value of any of the members.

Using the Code

Just implement the below mentioned methods in a class of your own:

private static string CompareObjects(object initialObj, object currentObj)
{
    string returnMessage = string.Empty;

    Type type = initialObj.GetType();
    Type type2 = currentObj.GetType();
    PropertyInfo[] propListInfo = type.GetProperties();
    PropertyInfo[] propListInfo1 = type2.GetProperties();

    //if class type is native i.e. string, int, boolean, etc.
    if (type.IsSealed == true && type.IsGenericType == false)
    {
        if (!initialObj.Equals(currentObj))
        {
            returnMessage = "initialObj value :{" + initialObj.ToString() + "},
                currentObj value :{" + currentObj.ToString() + "}";
        }
    }
    else //class type is object
    {
        //loop through each property of object
        for (int count = 0; count < propListInfo.Length; count++)
        {
            //check if it is an indexed object -- special case
            if (propListInfo[count].GetGetMethod().GetParameters().Length > 0)
            {
                // check if  not dict object --dict object needs to be addressed
                if (count > 1 && type.Name.IndexOf("Dictionary") == -1)
                {
                    int indexersTotal = 0;
                    //get index of count
                    for (int tmpCount = 0; tmpCount < propListInfo.Length; tmpCount++)
                    {
                        if (propListInfo[tmpCount].Name == "Count")
                        {
                            indexersTotal = (int)propListInfo[tmpCount].GetValue(
                                initialObj, null);

                            break;
                        }
                    }
                    //indexersTotal = 
                    //   (int)propListInfo[count - 1].GetValue(initialObj, null);
                    try
                    {
                        for (int curIndex = 0; curIndex < indexersTotal; curIndex++)
                        {
                            object Obj1 = propListInfo[count].GetValue(initialObj,
                                new object[] { curIndex });
                            object Obj2 = propListInfo1[count].GetValue(currentObj,
                                new object[] { curIndex });
                            returnMessage = Compare(Obj1, Obj2);
                            if (returnMessage.Length > 0)
                            {
                                return returnMessage + " " + 
				propListInfo[count].ToString();
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        //consume this error as it is occurred because of dictionary
                        //setting collection
                        string str = ex.Message;
                    }
                }
            }
            else //not an indexed object
            {
                object Obj1 = propListInfo[count].GetValue(initialObj, null);
                object Obj2 = propListInfo1[count].GetValue(currentObj, null);
                returnMessage = Compare(Obj1, Obj2);
                if (returnMessage.Length > 0)
                {
                    return returnMessage + " " + propListInfo[count].ToString();
                }
            }
        }
    }

    public static string Compare(object initialObj, object currentObj)
    {
        string returnMessage = "";
        if (initialObj == null && currentObj != null)
        {
            returnMessage = "initialObj is Null Object";
        }
        else if (initialObj != null && currentObj == null)
        {
            returnMessage = "currentObj is Null Object";
        }
        else if (initialObj != null && currentObj != null)
        {
            returnMessage = CompareObjects(initialObj, currentObj);
        }
        return returnMessage;
    }

History

• 11^th November, 2008: Initial post