RunTime Exception while Casting Variables/Objects

Question

I have variable PersonnelName in class VehicleMainModel. I want to get reference from object PersonnelObject of PersonnelMainViewModel.

When run my code following line throws Typecast exception:

PersonnelName = (bservableCollection) (PersonnelObject.Select(x => x.Name));

I don't understand how to resolve this. Even though both sides are list of string its not working. For your reference, I am attaching my both the classes here.

Please give working line for the same.

I have truncated unnecessary code for you.

enter image description here

vehicleMainViewModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Seris.Models;
using System.Collections.ObjectModel;
using System.Windows.Input;
using Seris.Commands;
using Seris.ViewModels;
using System.Windows;
using System.Windows.Controls;
using System.Threading;
using System.ComponentModel;
using Seris.Views;

namespace Seris.ViewModels
{
public class VehicleMainViewModel : ObservableObject
{

    #region Getters-Setters

// Static Variables...

    private static VehicleMainViewModel _Instance;
    public static VehicleMainViewModel getInstance
    {
        get
        {
            if(_Instance==null)
            {
                _Instance = new VehicleMainViewModel();
            }
            return _Instance;
        }
    }

    private static AddVehicle _addVehicle;
    public static AddVehicle addVehicle
    {
        get
        {
            return _addVehicle;
        }
        set
        {
            _addVehicle = value;
        }
    }

// Non-Static Variables...

   // Error Components

    . . .

    private string _PersonnelNameSelected;
    public string PersonnelNameSelected
    {
        get { return _PersonnelNameSelected; }
        set
        {
            if (value == null || (!value.Equals(_PersonnelNameSelected)))
            {
                _PersonnelNameSelected = value;
                EditText = _PersonnelNameSelected;
                OnPropertyChanged("PersonnelNameSelected");
                validateSpecificData(5);
            }
        }
    }


    private ObservableCollection<string> _PersonnelName;
    public ObservableCollection<string> PersonnelName
    {
        get { return _PersonnelName; }
        set
        {
            if (value != _PersonnelName)
            {
                _PersonnelName = value;
                OnPropertyChanged("PersonnelName");
            }
        }
    }

    private ObservableCollection<PersonnelModel> _PersonnelObject;
    public ObservableCollection<PersonnelModel> PersonnelObject
    {
        get { return _PersonnelObject; }
        set
        {
            if (value != _PersonnelObject)
            {
                _PersonnelObject = value;
                OnPropertyChanged("PersonnelObject");
            }
        }
    }

    private ObservableCollection<VehicleModel> _listItems;
    public ObservableCollection<VehicleModel> ListItems
    {
        get { return _listItems; }
        set
        {
            if (value == null || (!value.Equals(_listItems)))
            {
                _listItems = value;
            }
        }
    }

    // Other Variables

//Static Methods...

    public static void showMessage(string message)
    {
        MessageBox.Show(message);
    }

//Non-Static Methods...

    . . .

    public void clearAllData()
    {
        VehicleNo=null;
        Model=null;
        ManufacturingDate=null;
        IUNo=null;
        PersonnelNameSelected=null;

        VehicleNo_Error = "";
        Model_Error = "";
        ManufacturingDate_Error = "";
        IUNo_Error = "";
        Personnel_Error= "";
    }
    #endregion

    #region Constructors

    public VehicleMainViewModel()
    {
        // Initialization

        ListItems = new ObservableCollection<VehicleModel>();
        PersonnelObject = PersonnelMainViewModel.getInstance.Personnel_List;

//This line gives error//
        PersonnelName = (ObservableCollection<string>) (PersonnelObject.Select(x => x.Name));

        // Setting Flags
        ErrorMessage = "";
        IsEnableReplaceButton = false;


        // Commands Initialization

        . . .
    } 

    #endregion


}
}

PersonnelMainViewModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using System.ComponentModel;
using System.Windows.Markup;
using System.Windows.Data;
using System.Windows.Media.Imaging;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Documents;
using System.Windows.Controls.Primitives;
using System.Windows.Automation.Peers;
using System.Windows.Controls;
using System.Diagnostics;
using System.Security;
using System.Collections.ObjectModel;

using Seris.Models;
using Seris.Views;
using Seris.ViewModels;
using Seris.Properties;
using Seris.Commands;



namespace Seris.ViewModels
{
public class PersonnelMainViewModel :ObservableObject 
{
    public ObservableCollection<PersonnelModel> Personnel_List;
    private ObservableCollection<PersonnelModel> Personnel_copy;
    public PersonnelModel model = new PersonnelModel();
    public List<string> MyString;
    public ICommand EditCommand;
    public ICommand AddCommand;
    public bool isRemove;
    public static ObservableCollection<string> PersonNameList_Updating;

    private static PersonnelMainViewModel _Instance;
    public static PersonnelMainViewModel getInstance
    {
        get
        {
            if (_Instance == null)
            {
                _Instance = new PersonnelMainViewModel();
            }
            return _Instance;
        }
    }

    public PersonnelMainViewModel()
    {

        MyString = new List<string>();
        Personnel_copy = new ObservableCollection<PersonnelModel>();
       isRemove = false;
       Personnel_List = new ObservableCollection<PersonnelModel>
        {
             new PersonnelModel{ID=Guid.NewGuid(),Name="Mr.Joe",Gender="Male",Hospital="Poly Clinic",EMPID="abc 123",Capabilities="123",Position="Assistant",Title="Test",Status="General",ICNumber="IC 123",Roles="Test"},
             new PersonnelModel{ID=Guid.NewGuid(),Name="Su Su",Gender="Female",Hospital="Clementi Clinic",EMPID="abc 1234",Capabilities="1234",Position="Security",Title="Test",Status="General",ICNumber="IC 1234",Roles="Test"},
              new PersonnelModel{ID=Guid.NewGuid(),Name="Ms Tan",Gender="Female",Hospital="Bishan Clinic",EMPID="abc 1235",Capabilities="1235",Position="HR",Title="Test",Status="General",ICNumber="IC 1235",Roles="Test"},
        };

       Personnel_copy = new ObservableCollection<PersonnelModel>
    {
        new PersonnelModel{ID=Guid.NewGuid(),Name="Mr.Joe",Gender="Male",Hospital="Poly Clinic",EMPID="abc 123",Capabilities="123",Position="Assistant",Title="Test",Status="General",ICNumber="IC 123",Roles="Test"},
        new PersonnelModel{ID=Guid.NewGuid(),Name="Su Su",Gender="Female",Hospital="Clementi Clinic",EMPID="abc 1234",Capabilities="1234",Position="Security",Title="Test",Status="General",ICNumber="IC 1234",Roles="Test"},
        new PersonnelModel{ID=Guid.NewGuid(),Name="Ms Tan",Gender="Female",Hospital="Bishan Clinic",EMPID="abc 1235",Capabilities="1235",Position="HR",Title="Test",Status="General",ICNumber="IC 1235",Roles="Test"},
    };

        PersonNameList_Updating = new ObservableCollection<string> (Personnel_List.Select(x => x.Name));
        _hos = new ObservableCollection<string> (Personnel_List.Select(x=>x.Hospital) );

        EditCommand = new RelayCommand(Edit);
        AddCommand = new RelayCommand(Add);
        Removecommand = new RelayCommand(Remove);
        SearchCommand = new RelayCommand(search);

        //string[] textList = this.FindResource("Personnel_vm") as string[];
        //ICollectionView view = CollectionViewSource.GetDefaultView(textList);
        //new TextSearchFilter(view, this.txtSearch);


       }


   . . .

    #endregion

   . . .
    }
}

VehicleModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.ObjectModel;
using System.Text.RegularExpressions;
using Seris.ViewModels;

namespace Seris.Models
{
public class VehicleModel : ObservableObject
{
    #region Getters-Setters

    private Guid? _UniqueNo;
    public Guid? UniqueNo
    {
        get { return _UniqueNo; }
        set
        {
            if (value != _UniqueNo)
            {
                _UniqueNo = value;
                OnPropertyChanged("UniqueNo");

            }
        }
    }

    private string _VehicleNo;
    public string VehicleNo 
    {
        get { return _VehicleNo; }
        set
        {
            if (value != _VehicleNo)
            {
                _VehicleNo = value.Trim();
                OnPropertyChanged("VehicleNo");
            }
        }
    }

    private string _Model;
    public string Model
    {
        get { return _Model; }
        set
        {
            if (value != _Model)
            {
                _Model = value.Trim();
                OnPropertyChanged("Model");
            }
        }
    }

    private DateTime? _ManufacturingDate;
    public DateTime? ManufacturingDate
    {
        get { return _ManufacturingDate; }
        set
        {
            if (value != _ManufacturingDate)
            {
                _ManufacturingDate = value;
                OnPropertyChanged("ManufacturingDate");
            }
        }
    }

    private string _IUNo;
    public string IUNo
    {
        get { return _IUNo; }
        set
        {
            if (value != _IUNo)
            {
                _IUNo = value.Trim();
                OnPropertyChanged("IUNo");
            }
        }
    }

    private string _PersonnelNameSelected;
    public string PersonnelNameSelected
    {
        get { return _PersonnelNameSelected; }
        set
        {
            if (value != _PersonnelNameSelected)
            {
                _PersonnelNameSelected = value;
                OnPropertyChanged("PersonnelNameSelected");
            }
        }
    }


    #endregion

    #region Methods

    // Validating Forms
    private void ValidateAllData(Object sender)
    {
        bool errorFlag=false;

        if (!Validate_VehicleNo())
        {
            errorFlag = true;
        }
        if (!Validate_Model())
        {
            errorFlag = true;
        }

        if (!Validate_ManufacturingDate())
        {
            errorFlag = true;
        } 
        if (!Validate_IUNo())
        {
            errorFlag = true;
        }
        if (!Validate_PersonnelName()) // For Future Enhancement
        {
            errorFlag = true;
        }

        // Personnel Remaining..........//

        if (errorFlag)
            throw (new Exception("Invalid Details\nClick on Help for details"));


    }
    public void ValidateSpecificData(Object sender, int ErrorObj)
    {
        bool errorFlag = false;

        if (sender is VehicleMainViewModel)
        {
            VehicleMainViewModel senderObject = (VehicleMainViewModel)sender;

            errorFlag = false;
            switch(ErrorObj)
            {
                case 1:
                    if (!Validate_VehicleNo())
                    {
                        senderObject.VehicleNo_Error = "3 Caps alphabet following 4 numericals only";
                        errorFlag = true;
                    }
                    else
                        senderObject.VehicleNo_Error = "";
                    break;
                case 2:
                    if (!Validate_Model())
                    {
                        senderObject.Model_Error = "Mandatory Field";
                            errorFlag = true;
                    }
                    else
                        senderObject.Model_Error = "";
                    break;
                case 3:
                    if (!Validate_ManufacturingDate())
                    {
                        senderObject.ManufacturingDate_Error = "Can't be blank or future Date";
                        errorFlag = true;
                    }
                    else
                        senderObject.ManufacturingDate_Error = "";
                    break;
                case 4:
                    if (!Validate_IUNo())
                    {
                        senderObject.IUNo_Error = "10 digits numerical only";
                        errorFlag = true;
                    }
                    else
                        senderObject.IUNo_Error = "";
                    break;
                case 5:
                    if (!Validate_PersonnelName())
                    {
                        senderObject.Personnel_Error = "Mandatory Fvnield";
                        errorFlag = true;
                    }
                    else
                        senderObject.Personnel_Error = "";
                    break;
            }

        }
    }
    // To Check Regular Expressions
    public bool matchRE(string stringToMatch, string regularExpression)
    {
        Regex regex = new Regex(@regularExpression);
        Match match = regex.Match(stringToMatch);

        if (match.Success)
            return (true);
        else
            return (false);
    }

    #region Validate Methods

    public bool Validate_VehicleNo()
    {
        if (VehicleNo == null || VehicleNo.Trim().Length==0)
            return false;
        if (matchRE(VehicleNo,"[A-Zz-z][A-Zz-z0-9]{6}"))
            return true;
        else
            return false;
    }
    public bool Validate_Model()
    {
        if (Model == null || Model.Trim().Length==0)
            return false;
        if(Model!=null || Model.Length==0)
            return true;
        else
            return false;
    }
    public bool Validate_ManufacturingDate()
    {
        if (ManufacturingDate == null || ManufacturingDate.ToString().Trim().Length == 0)
            return false;
        if( ManufacturingDate > DateTime.Now )
            return false;
        return true;
    }
    public bool Validate_IUNo()
    {
        if (IUNo == null || IUNo.Trim().Length==0)
            return false;
        if(matchRE(IUNo,"[0-9]{10}"))
            return true;
        else
            return false;
    }
    public bool Validate_PersonnelName()
    {
        if (PersonnelNameSelected == null || PersonnelNameSelected.Trim().Length == 0)
            return false;
        else
            return true;

    }  


    #endregion

    #endregion

    #region Constructors

    public VehicleModel(string VehicleNo, string Model, DateTime? ManufacturingDate, string IUNo, string PersonnelNameSelected)
    {
        this.UniqueNo = Guid.NewGuid();
        this.VehicleNo = VehicleNo;
        this.Model = Model;
        this.ManufacturingDate = ManufacturingDate;
        this.IUNo = IUNo;
        this.PersonnelNameSelected = PersonnelNameSelected;

        ValidateAllData(this);
    }

    public VehicleModel()
    {
        UniqueNo = null;
        VehicleNo = null;
        Model = null;
        ManufacturingDate = null;
        IUNo = null;
        PersonnelNameSelected = null;

    }
    #endregion
}
}

AddVehicle.xaml

<Window x:Class="Seris.Views.AddVehicle"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="AddVehicle" Height="650" Width="750"
    xmlns:l="clr-namespace:Seris.ViewModels">
<Grid>

    <Label Content="Add Vehicle" HorizontalAlignment="Left" Height="27" Margin="261,8,0,0" VerticalAlignment="Top" Width="85" FontWeight="Bold" FontSize="12"/>
    <Label Content="SERIS CAD" HorizontalAlignment="Left" Height="30" Margin="61,5,0,0" VerticalAlignment="Top" Width="84" FontWeight="Bold"/>
    <Menu x:Name="AddNewPersonnel" HorizontalAlignment="Left" Height="32" Margin="10,32,-329,0" VerticalAlignment="Top" Width="611">
        <MenuItem Header="Manage Vehicle &gt;&gt;" Margin="0" />
        <MenuItem Header="Add Vehicle &gt;&gt;" Margin="0" />
    </Menu>
    <GroupBox Header="Vehicle Information" HorizontalAlignment="Left" Height="267" Margin="10,64,0,0" VerticalAlignment="Top" Width="611" FontWeight="Bold" FontSize="12"/>
    <Canvas HorizontalAlignment="Left" Height="352" Margin="18,91,0,0" VerticalAlignment="Top" Width="603">

        <Label Content="Vehical No" HorizontalAlignment="Left" Height="27" Width="104" Margin="10,10,0,232"/>
        <TextBox Name="VehicalNo_Text" Height="27" Width="193" TextWrapping="Wrap" MaxLength="7" Text="{Binding VehicleNo, UpdateSourceTrigger=PropertyChanged}"  HorizontalAlignment="Left" Margin="85,10,0,239" />
        <Label Name="VehicleNoError_Label" Foreground="Red" Content="{Binding VehicleNo_Error, UpdateSourceTrigger=PropertyChanged}" Height="27" Width="275" Canvas.Left="323" Canvas.Top="10"/>

        <Label Content="Model" HorizontalAlignment="Left" Height="27" Width="104" RenderTransformOrigin="0.49,-2.185" Canvas.Left="10" Canvas.Top="62"/>
        <TextBox Name="Model_Text" Height="27" Width="193" TextWrapping="Wrap" MaxLength="15" Text="{Binding Model, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Canvas.Left="85" Canvas.Top="62" />
        <Label x:Name="ModelError_Label" Foreground="Red" Content="{Binding Model_Error, UpdateSourceTrigger=PropertyChanged}" Height="27" Width="275" Canvas.Left="323" Canvas.Top="62"/>

        <Label Content="Manu. Date" HorizontalAlignment="Left" Height="27" Width="104" Canvas.Left="10" Canvas.Top="112"/>
        <DatePicker x:Name="ManufacturingDate_DateTime" SelectedDate="{Binding ManufacturingDate, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="193" Height="25" Canvas.Left="85" Canvas.Top="114"/>
        <Label Name="ManufacturingDateError_Label" Foreground="Red" Content="{Binding ManufacturingDate_Error, UpdateSourceTrigger=PropertyChanged}" Height="27" Width="275" Canvas.Left="323" Canvas.Top="112"/>

        <Label Content="IU No" HorizontalAlignment="Left" Height="27" Width="104" Canvas.Left="10" Canvas.Top="157"/>
        <TextBox Height="27" Width="193" Name="IUNO_Text" TextWrapping="Wrap" MaxLength="10" Text="{Binding IUNo, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Canvas.Left="85" Canvas.Top="157"/>
        <Label Name="IUError_Label" Foreground="Red" Content="{Binding IUNo_Error, UpdateSourceTrigger=PropertyChanged}" Height="27" Width="275" Canvas.Left="323" Canvas.Top="157"/>

        <Label Content="Personnel" HorizontalAlignment="Left" Height="27" Width="104" Canvas.Left="10" Canvas.Top="198"/>
        <ComboBox x:Name="Personnel_Combo" SelectedValue="{Binding PersonnelNameSelected, UpdateSourceTrigger=PropertyChanged}" ItemsSource="{Binding PersonnelName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Height="27" Width="193" Canvas.Left="85" Canvas.Top="198"/>
        <Label Name="Personnel_Label" Foreground="Red" Content="{Binding Personnel_Error, UpdateSourceTrigger=PropertyChanged}" Height="27" Width="275" Canvas.Left="318" Canvas.Top="198"/>

    </Canvas>

    <Label x:Name="Error_Label" Content="{Binding ErrorMessage, UpdateSourceTrigger=PropertyChanged}" Foreground="Red" HorizontalAlignment="Left" Width="236" Margin="187,345,0,200"/>

    <Button Name="Help" Visibility="{Binding HelpVisibility, UpdateSourceTrigger=PropertyChanged}" Command="{Binding OpenHelpWindow_Command}" Height="50" Width="50" Margin="562,377,80,143">
        <Button.DataContext>
            <l:VehicleHelpViewModel />
        </Button.DataContext>
        <Image Height="45" Width="45" Source="../Images/help.jpg"/>
    </Button>

    <Button Name="Save_Button" Command="{Binding SaveButton_Command}" CommandParameter="save" Height="28" Width="81" Content="Save" Margin="265,392,346,150"/>

    <TextBlock Name="Preview" Text="{Binding EditText, UpdateSourceTrigger=PropertyChanged}" Margin="13,377,542,168"/>


</Grid>
</Window>

score 1 · Answer 1 · answered Aug 08 '14 at 03:10

1

You can create ObservableCollection by initializing it like this

PersonnelName = new ObservableCollection(PersonnelObject.Select(x => x.Name));

Or

PersonnelName = new ObservableCollection<string>(PersonnelObject.Select(x => x.Name));

answered Aug 08 '14 at 03:10

Manish Parakhiya

3,732
3
22
25

I did but in this case it is copying it not referring to it. I want to give reference, So that if right hand side object changes, left also. – Pratik Aug 08 '14 at 03:17

pushpraj · Accepted Answer · 2014-08-08T04:01:17.327

1

since Select method returns an IEnumerable<T> you may perhaps do this way

IEnumerable<string> personNames = PersonnelObject.Select(x => x.Name);
PersonnelName = new ObservableCollection<string>();// optional if not initialized
foreach(string pName in personNames )
{
    PersonnelName.Add(pName);
}

as the Select method returns an IEnumerable which will not propagate changes made in source collection you may perhaps solve the issue via binding itself

here is a sample for combobox

<ComboBox ItemsSource="{Binding PersonnelObject}"
          DisplayMemberPath="Name" />

in above example ComboBox binds to the source collection PersonnelObject while displaying the Name property

you may perhaps revise the binding as

<ComboBox x:Name="Personnel_Combo"
          SelectedValue="{Binding PersonnelNameSelected, UpdateSourceTrigger=PropertyChanged}"
          ItemsSource="{Binding PersonnelObject}"
          DisplayMemberPath="Name"
          SelectedValuePath="Name"
          HorizontalAlignment="Left"
          Height="27"
          Width="193"
          Canvas.Left="85"
          Canvas.Top="198" />

note that I have changed the ItemsSource to bind to PersonnelObject and used the SelectedValuePath and DisplayMemberPath property to display and store the correct value.

edited Aug 08 '14 at 04:01

answered Aug 08 '14 at 03:11

pushpraj

13,458
3
33
50

Please read my comment below Manish's answer – Pratik Aug 08 '14 at 03:26
are you using the property `PersonnelName` for binding (display to UI) or for some other purpose? – pushpraj Aug 08 '14 at 03:27
Yes . Now you got it. I have made it observable also That' why. – Pratik Aug 08 '14 at 03:28
do please share the xaml for the same. – pushpraj Aug 08 '14 at 03:29
Actually I don't want to confuse you all by putting extra code. I have multiple windows in UI. Can you resolve it w/o xaml? – Pratik Aug 08 '14 at 03:35
to solve the issue in code only may require to wrap the source collection in another collection which will listen to changes in the source collection and update itself. would what be ok to you? – pushpraj Aug 08 '14 at 03:39
I am sorry , I am beginner to WPF/C#, so couldn't understand but can you please give an example for my code? – Pratik Aug 08 '14 at 03:42
1

here is an implementation of a wrapper collection http://stackoverflow.com/questions/13920703/observablecollection-element-wise-transform-projection-wrapper, this will transform the PersonnelObject collection to an ObservableCollection see if that is worth over the xaml changes. – pushpraj Aug 08 '14 at 03:44
pushpraj I used binding, also setter method is called but list is not updating. See, I have added xaml for your reference. – Pratik Aug 08 '14 at 03:50
Hey Thanks, had some issue in colleague's code for Singleton pattern. Now its working. Thanks :) +1 for your continues efforts :) – Pratik Aug 08 '14 at 05:02

RunTime Exception while Casting Variables/Objects

2 Answers2