Compare Object List – Determine Insert, Update and Delete data

I was working on this scenario and breaking my head to come up with simple solution to compare two large list of object (List<object>) and get the result as new (Insert), update and delete data. Found out that there is simple solution and I thought will publish it so that it can help others.

I have put generic code which anyone can copy and start using right away.

New data

/// <summary> /// Returns the newly added /// </summary> /// <param name="existingData">Existing data</param> /// <param name="newData">New data</param> /// <returns>List of objects which are newly added</returns> public List<object> GetInsertData(List<object> existingData, List<object> newData) {     // Local objects     List<object> returnList = null;     // Prepare the list which has the data to be inserted     returnList = (from New in newData                   join Existing in existingData on New.ID equals Existing.ID                   into DataAdded                   from dataOld in DataAdded.DefaultIfEmpty()                   where dataOld == null                   select New).ToList<object>();     // Return the data list     return returnList; }

Updated data

/// <summary> /// Returns the data updated /// </summary> /// <param name="existingData">Existing data</param> /// <param name="newData">New data</param> /// <returns>List of objects which are updated</returns> public List<object> GetUpdateData(List<object> existingData, List<object> newData) {     // Local objects     List<object> returnList = null;     returnList = (from New in newData                   join Existing in existingData on New.ID equals Existing.ID                   into DataUpdated                   from dataOld in DataUpdated.DefaultIfEmpty()                   where dataOld!= null && (New.<Field1>!= dataOld.<Field1> || New.<Field2> != dataOld.<Field2>)                   select new object                   {                        Field1 = New.Value1,                         Field2 = New.Value2,                         Field3 = dataOld.Value3,                         Field4 = dataOld.Value4,                    }).ToList<object>();             // Return the data list             return returnList;         }

Delete data

/// <summary> /// Returns the deleted rows /// </summary> /// <param name="existingData">Existing data</param> /// <param name="newData">New data</param> /// <returns>List of schools which needs to be deleted</returns> public List<object> GetDeleteData(List<object> existingData, List<object> newData) {     // Local objects     List<object> returnList = null;     // Prepare the list which has the data to be deleted     returnList = (from Existing in existingData                      join New in newData on Existing.ID equals New.ID                      into NewWithNullForDeleted                      from subNew in NewWithNullForDeleted.DefaultIfEmpty()                      where subNew == null                      select Existing).ToList<School>();      // Return the data list      return returnList; }

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