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Something is getting wrong with adding a list to existing List

I'm trying to realize the listBox with List where i getting some variable.
And when i wonna to add a new "Object" to static List i getting a NullReferenceException
This is my code where i adding a new List
if (EventArgsIn.Message.Chat.Id == MainChatId)
{
if (EventArgsIn.Message.ReplyToMessage != null)
{
var _tempMessage = new listBoxMessage()
{
From = EventArgsIn.Message.From.Username,
FromId = EventArgsIn.Message.From.Id,
MessageId = EventArgsIn.Message.MessageId,
MessageText = EventArgsIn.Message.Text,
MessageIdReply = 0
};
tempMessageMain.Add(_tempMessage);
} else
{
var _tempMessage = new listBoxMessage() {
From = EventArgsIn.Message.From.Username,
FromId = EventArgsIn.Message.From.Id,
MessageId = EventArgsIn.Message.MessageId,
MessageText = EventArgsIn.Message.Text,
MessageIdReply = 0
};
tempMessageMain.Add(_tempMessage);
}
}
And here is my static List
public static List<listBoxMessage> tempMessageMain;
A-a-and my class where i doing Template
public class listBoxMessage
{
public listBoxMessage()
{
}
public string From { get; set; }
public int FromId { get; set; }
public int MessageId { get; set; }
public string MessageText { get; set; }
public int MessageIdReply { get; set; }
}
}
This is test code*

You declared a listbox with next line:
public static List<listBoxMessage> tempMessageMain;
The value of tempMessageMain is still null.
Now you have to create a new instance of tempMessageMain:
public static List<listBoxMessage> tempMessageMain = new List<listBoxMessage>();

Get subclass content from object

I have the following classes
public enum Category { foo, foo1, foo2 }
public class Event
{
public DateTime Timestamp { get; set; } = DateTime.Now;
public string GameTime { get; set; }
public string Content { get; set; }
public Person Author { get; set; }
public Category Category { get; set; }
}
and
public class MemberEvent : Event
{
public Member Person { get; set; }
}
The object is created correctly, but if I want to call "Person", this is not displayed to me. If I have a var match, I can call for example match[0].Timestamp but not match[0].Person. The Event object is stored in a List, therefore also the index. I feel I'm missing something simple.
UPDATE: The Code that create the Object
var match = SessionController.Instance.Current;
DataTable dt = dataGrid.ItemsSource as DataTable;
foreach (System.Data.DataRow item in dt.Rows)
{
var memberFoo = new MemberEvent();
memberFoo.Category = Category.Warning;
memberFoo.Time = item["Time"].ToString();
var person = new Person();
person.FirstName = item["FirstName"].ToString();
person.LastName = item["LastName"].ToString();
var passport = new Passport();
passport.Active = true;
passport.PassNumber = item["Pass"].ToString();
passport.Player = person;
memberFoo.Person = passport;
match.Match.Events.Add(memberFoo);
}
SessionController.Instance.Current = match;

Cast your instance to the expected type and test for null to guard for the unexpected:
var memberEvent = match[0] as MemberEvent;
if (memberEvent != null)
{
Console.WriteLine(memberEvent.Person)
}

You will have to cast your Event into a MemberEvent if you want to access the Person property. It is not possible to get the property from Event.
List<Event> myEvents = GetMyEvents();
var myMemberEvent = (MemberEvent)myEvent[0];
It can cause an exception if it can't convert to MemberEvent.

Dropdown has a SelectedValue which is invalid because it does not exist in the list of items, even though I cleared the selected items (C#)

I'm getting this error on DataBind(), and I don't know why since there shouldn't be anything selected.
DdState.Items.Clear();
DdState.DataSource = UsStates;
DdState.DataTextField = "Title";
DdState.DataValueField = "Title";
DdState.Items.Insert(0, String.Empty);
if (DdState.SelectedItem != null)
{
DdState.SelectedItem.Selected = false;
}
DdState.DataBind();
private IEnumerable<IStateItem> UsStates
{
get
{
var statesFolder = _sitecoreService.GetItem<ISitecoreItem>(ItemReference.BcsUs_ProductData_States.Guid);
if (statesFolder == null)
return new List<IStateItem>();
List<IStateItem> usStates = _sitecoreService.QueryChildren<IStateItem>(statesFolder).OrderBy(s => s.Title).ToList();
return usStates;
}
}
I tried putting in DdState.SelectedIndex = 0 before the DataBind(), but then I got an error that the selected index did not exist. What's going on?

If the DataSource is a list its much easier to implement. So just "convert" the UsStates IEnumerable to a List an then add it to the data source.
DdState.DataSource = UsStates.ToList();
Then choose the property of a list item as binding.
OR
public Form1()
{
InitializeComponent();
DdState.Items.Clear();
DdState.DataSource = UsStates;
DdState.DisplayMember = "Statename";
DdState.SelectedIndex = 0;
}
private List<IStateItem> UsStates
{
get
{
List<IStateItem> usStates = new List<IStateItem>();
usStates.Add(new IStateItem("California","status1"));
usStates.Add(new IStateItem("Ohio", "status3"));
return usStates;
}
}
private class IStateItem
{
public IStateItem(string statename, string stateStatus)
{
Statename = statename;
StateStatus = stateStatus;
}
public string Statename { get; set; }
public string StateStatus { get; set; }
}

Could there be something wrong with your IStateItem class?
I copy/pasted your code in a new asp.net application, made my own IStateItem class and it works.
using System;
using System.Collections.Generic;
namespace TestIt
{
public partial class Form1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
FillTheList();
}
private void FillTheList()
{
ddl_TheList.Items.Clear();
ddl_TheList.DataSource = UsStates;
ddl_TheList.DataTextField = "statename";
ddl_TheList.DataValueField = "stateStatus";
//ddl_TheList.Items.Insert(0, String.Empty);
ddl_TheList.DataBind();
ddl_TheList.SelectedIndex = 0;
}
private IEnumerable<IStateItem> UsStates
{
get
{
List<IStateItem> usStates = new List<IStateItem>();
for (int i = 0; i < 10; i++)
{
usStates.Add(new IStateItem { statename = "state #" + i, stateStatus = "cool state bro" });
}
return usStates;
}
}
}
public class IStateItem
{
public string statename { get; set; }
public string stateStatus { get; set; }
}
}

Refactor query in LINQ

I have a query that needs to check the value from object list if it exists by loop through the value of the main object. How can recode below?
foreach (var kd in dto.KeyDriverModels)
{
var keyDriverModelNodeValue = result.SingleOrDefault(x => x.KeyDriverModelId == kd.ID);
kd.SelectionStatus = keyDriverModelNodeValue != null ?
keyDriverModelNodeValue.SelectionStatus : string.Empty;
}

I tried to model your code and rewrite the code as Linq. See if this works
static DTO dto = new DTO();
static void Main(string[] args)
{
List<KeyDriver> keyDrivers = new List<KeyDriver>();
List<KeyDriver> result = keyDrivers.Where(x => x.KeyDriverModelId > 1000).ToList();
foreach (var kd in dto.KeyDriverModels)
{
var keyDriverModelNodeValue = result.SingleOrDefault(x => x.KeyDriverModelId == kd.ID);
kd.SelectionStatus = keyDriverModelNodeValue != null ?
keyDriverModelNodeValue.SelectionStatus : string.Empty;
}
//new code
var kd1 = from r in result
join d in dto.KeyDriverModels
on r.KeyDriverModelId equals d.ID into drs
from dr in drs
select new { dr }.dr.SelectionStatus != null ? dr.SelectionStatus : string.Empty;
}
}
public class DTO
{
public List<KeyDriverModel> KeyDriverModels { get; set; }
}
public class KeyDriverModel
{
public int ID { get; set; }
public string SelectionStatus { get; set; }
}
public class KeyDriver
{
public int KeyDriverModelId { get; set; }
public string SelectionStatus { get; set; }
}
​

Comparison of Objects (Multiple Levels)

I want to create objects with 5 properties and each properties has 2 attributes. After that, I compare the objects if they are same, they will be grouped in same category.
Here is the code:
Item.cs
public class Item
{
public Item()
{
}
public SortProperty SortPropA { get; set; }
public SortProperty SortPropB { get; set; }
public SortProperty SortPropC { get; set; }
public SortProperty SortPropD { get; set; }
public SortProperty SortPropE { get; set; }
public string Name { get; set; }
public string Desc { get; set; }
}
SortProperty.cs
public class SortProperty : IEquatable<SortProperty>
{
public string PartName { get; set; }
public string GroupabilityID { get; set; }
public SortProperty()
{
}
public override int GetHashCode()
{
int hash = 19;
hash = hash * 31 + (GroupabilityID == null ? 0 : GroupabilityID.GetHashCode());
hash = hash * 31 + (PartName == null ? 0 : PartName.GetHashCode());
return hash;
}
public bool Equals(SortProperty obj)
{
return (obj == null) ?
false : (GroupabilityID == obj.GroupabilityID) || (PartName == obj.PartName);
}
public override bool Equals(Object obj)
{
SortProperty itemobj = obj as SortProperty;
return itemobj == null ? false : Equals(itemobj);
}
}
Program.cs (main class to test the coding)
class Program
{
static void Main(string[] args)
{
Item objA = new Item();
Item objB = new Item();
// ------ Object A
objA.Name = "Card1";
objA.Desc = "Product Test A";
//Property A
objA.SortPropA = new SortProperty();
objA.SortPropA.PartName = "Plastic A";
objA.SortPropA.GroupabilityID = "A1";
//Property B
objA.SortPropB = new SortProperty();
objA.SortPropB.PartName = "Color Green";
objA.SortPropB.GroupabilityID = "B2";
//Property C
objA.SortPropC = new SortProperty();
objA.SortPropC.PartName = "Visa";
objA.SortPropC.GroupabilityID = "C1";
// ------ Object B
objB.Name = "Card2";
objB.Desc = "Product Test B";
//Property A
objB.SortPropA = new SortProperty();
objB.SortPropA.PartName = "Plastic B";
objB.SortPropA.GroupabilityID = "A2";
//Property B
objB.SortPropB = new SortProperty();
objB.SortPropB.PartName = "Color Lime";
objB.SortPropB.GroupabilityID = "B1";
//Property C
objB.SortPropC = new SortProperty();
objB.SortPropC.PartName = "Visa";
objB.SortPropC.GroupabilityID = "C1";
bool isEqual = objA.Equals(objB);
if (isEqual == true)
Console.WriteLine("Is same");
else
Console.WriteLine("Is different");
Console.ReadKey();
}
}
The result should return true because there is a same property between objA and objB (SortPropc) but it return false.
I believe I have miss some logic part and I have sitting on chair for 4 hours but couldn't fix it. Can anyone please solve it?

The result should return true because there is a same property between objA and objB (SortPropc) but it return false.
You have just not implemented it. Read your code again and try to find the piece where you actually compare two Item instances. There's is none.
You should implement an Equals and GetHashCode method on your Item class, something like this:
public override bool Equals(Object obj)
{
var o = (Item)obj;
// Note: not error checking :-)
return SortPropA.Equals(o.SortPropA) ||
SortPropB.Equals(o.SortPropB) ||
SortPropC.Equals(o.SortPropC) ||
SortPropD.Equals(o.SortPropD) ||
SortPropE.Equals(o.SortPropE);
}
or create a class that implements IEqualityComparer<Item> that handles this requirement.