How To Compare 2 Lists Determining If A Property Has Changed, Ignoring Order

In the list you want to perform the comparison against, override Equals

 [Serializable]
    public class AlertSubscriptionOption
    {
..
.
  /// <summary>
        /// Determines whether the specified <see cref="System.Object" />, is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="System.Object" /> to compare with this instance.</param>
        /// <returns>
        ///   <c>true</c> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <c>false</c>.
        /// </returns>
        public override bool Equals(object obj)
        {
            // Check for null values and compare run-time types.
            if (obj == null || GetType() != obj.GetType())
                return false;

            AlertSubscriptionOption p = (AlertSubscriptionOption)obj;
            return this.SubType == p.SubType;
        }

Now, to compare the 2 lists, perform the following

   
     bool subscriptionEmailDifferent = false;
   
            
    subscriptionEmailDifferent = (newSubscriptionEmailOptions.Count > 0 || oldSubscriptionEmailOptions.Count > 0) &&
                                          !newSubscriptionEmailOptions.OrderBy(x => x.SubType).ToList().SequenceEqual(oldSubscriptionEmailOptions.OrderBy(x => x.SubType).ToList());

References:

http://stackoverflow.com/questions/12795882/quickest-way-to-compare-two-list
http://stackoverflow.com/questions/188141/list-orderby-alphabetical-order

Determine if there are deltas/diffs Between Two Lists Of Same DataType

// Determine if there are unsaved changes
 var changedItems = from item1 in BoundJHAStaleNotifications
 from item2 in JHAStaleNotifications
 where item1.JHAStatus == item2.JHAStatus
 && item1.StaleUserType == item2.StaleUserType
 && ItemsAreDifferent(item1, item2)
 select item1;

 if (changedItems.Count() > 0)
 {
 ((EHAP_MasterPage)Master).ErrorMessage = "There are unsaved changes on this tab. Please either Save or Cancel before proceeding.";
 return;
 }

private bool ItemsAreDifferent(JHAStaleNotification item1, JHAStaleNotification item2)
 {

 bool ItemsAreDifferent = (item1.JHAStatus == item2.JHAStatus &&
 item1.StaleUserType == item2.StaleUserType &&
 item1.EntityStateType == item2.EntityStateType &&
 item1.Frequency == item2.Frequency &&
 item1.SendNotification == item2.SendNotification &&
 item1.Threshold == item2.Threshold);

 return !ItemsAreDifferent;

 }

How To Easily Compare 2 Lists To Determine Differences

This will work with complex types too.

bool changesMade = ListOne.SequenceEqual(ListTwo);

Note this uses the default equality compare (Equals). You may need to override the equals.

 public override bool Equals(object obj)
        {
            if (obj is JHAStaleNotification)
            {
                JHAStaleNotification other = (JHAStaleNotification)obj;
                return (this.JHAStatus == other.JHAStatus && 
                    this.StaleUserType == other.StaleUserType &&
                    this.EntityStateType == other.EntityStateType &&
                    this.Frequency == other.Frequency &&
                    this.SendNotification == other.SendNotification &&
                    this.Threshold == other.Threshold);
            }
            else
                return false;
        }

Another Clean Way To Remove Dupes From Lists

List withDupes = LoadSomeData();
List noDupes = withDupes.Distinct().ToList();

Adding a List To The End Of Another List

Just use the method .AddRange on the List you want to append to passing in the other list.

List1.AddRange(List2);

Remove Items From Generic List Given Another List Using LINQ

Let’s say you have two lists and you want to remove the items from one list using the items from another.

This assumes both Lists are of the same type.

                
                FullList = (from a in FullList
                            where !RemoveList.Contains(a)
                            select a).ToList();

Sorting Lists With Linq and Lamdas

Function to Sort List by “Text” property using Linq

        private List<TVEntity> sortTVObject(List<TVEntity> tvs)
        {
            var sortedTVs =
       from t in tvs
       orderby t.Text
       select t;

            return sortedTVs.ToList();
        }

TVEntity.cs (Object)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace com.dereksandbox.bl.Entities
{
    [Serializable]
    public class TVEntity
    {
        public string Text { get; set; }
        public string Value { get; set; }
    }
}

Execution

            List<TVEntity> TVs = new List<TVEntity>();

            // create some dummy data
            TVs.Add(new TVEntity() { Text = "Samsung", Value = "1" });
            TVs.Add(new TVEntity() { Text = "LG", Value = "2" });
            TVs.Add(new TVEntity() { Text = "Song", Value = "3" });
            TVs.Add(new TVEntity() { Text = "Apex", Value = "4" });
            TVs.Add(new TVEntity() { Text = "Olevia", Value = "5" });
            TVs.Add(new TVEntity() { Text = "Mitshibi", Value = "6" });
            TVs.Add(new TVEntity() { Text = "Sharp", Value = "7" });

            SortedAvailableChoices = sortTVObject(TVs);

You could also use Lamda’s to perform the sorting as well:

List<TVEntity> TVs = new List<TVEntity>();

// create some dummy data
TVs.Add(new TVEntity() { Text = "Samsung", Value = "1" });
TVs.Add(new TVEntity() { Text = "LG", Value = "2" });
TVs.Add(new TVEntity() { Text = "Song", Value = "3" });
TVs.Add(new TVEntity() { Text = "Apex", Value = "4" });
TVs.Add(new TVEntity() { Text = "Olevia", Value = "5" });
TVs.Add(new TVEntity() { Text = "Mitshibi", Value = "6" });
TVs.Add(new TVEntity() { Text = "Sharp", Value = "7" });           

// sort using a Lamda expression
TVs.Sort((x, y) => (x.Text.CompareTo(y.Text)));  

Filtering Lists In .NET 2.0

In 3.x+ you can use LINQ and Lambda’s. In 2.0 a nice way to filter lists is by using the FindAll method passing in a search predicate.

List.FindAll Method At MSDN

example:

...
..
.
  return list.FindAll(FilterInsiderFilings);

}

private static bool FilterInsiderFilings(InvestorFilingData investorFilingData)
        {
            // search predicate to filter out insider filings (forms 3, 4, 5)
            if (investorFilingData.Filing == "3" | investorFilingData.Filing == "4" | investorFilingData.Filing == "5")
            {
                return true;
            }
            else
            {
                return false;
            }
        }

Convert List to DataTable – (ListToDataTable function)

using System.Data;
using System.Reflection;

private static DataTable ListToDataTable<T>(List<T> list)
        {
            DataTable dt = new DataTable();

            foreach (PropertyInfo info in typeof(T).GetProperties())
            {
                dt.Columns.Add(new DataColumn(info.Name, info.PropertyType));
            }
            foreach (T t in list)
            {
                DataRow row = dt.NewRow();
                foreach (PropertyInfo info in typeof(T).GetProperties())
                {
                    row[info.Name] = info.GetValue(t, null);
                }
                dt.Rows.Add(row);
            }
            return dt;
        }

Example implementation:

        List<InvestorFilingData> lst = FilingsLogic.GetInvestorFiling();
        DataTable dt = ListToDataTable(lst);

Example use: When you have an object bound to a GridView and want to sort the columns.