Could not create an instance of type

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Well I got this error right after I changed something, but I can't remember what, and even after noticing this thing I UNDOed everything I have done before the error, and still - no answer.

I'm working on a project witch uses an element host. The elementHost should connect to my Usercontroll, witch looks like this:

<usercontrol>
    x:Class="CustomCalendar.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:CustomCalendar"
    xmlns:toolkit="http://schemas.microsoft.com/wpf/2008/toolkit"
    xmlns:primitives="clr-namespace:Microsoft.Windows.Controls.Primitives;assembly=WPFToolkit"
    xmlns:vsm="clr-namespace:System.Windows;assembly=WPFToolkit"     
    Width="500"
    Height="400" FlowDirection="RightToLeft">

    <grid>
        <local:monthviewcalendar xmlns:local="#unknown" />
    </grid>
</usercontrol>

The "MonthViewCalendar" is only a class, without any xaml files in it, and the code of this class is:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Drawing;
using System.Data;
using Microsoft.Windows.Controls;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Data.SqlClient;
using System.Text.RegularExpressions;

namespace CustomCalendar
{
    // <summary>
    // Custom calendar control that supports appointments.
    // </summary>
    public class MonthViewCalendar : Calendar, INotifyPropertyChanged
    {
        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion

        public static DependencyProperty AppointmentsProperty =
            DependencyProperty.Register
            (
                "Appointments",
                typeof(ObservableCollection<appointment>),
                typeof(Calendar)
            );

        // <summary>
        // The list of appointments. This is a dependency property.
        // </summary>
        // 

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);

        private const int MOUSEEVENTF_LEFTDOWN = 0x02;
        private const int MOUSEEVENTF_LEFTUP = 0x04;
        private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        private const int MOUSEEVENTF_RIGHTUP = 0x10;
        private bool addingApp = false;
        bool HiddingForm = false;
        public ObservableCollection<appointment> Appointments
        {
            get { return (ObservableCollection<appointment>)GetValue(AppointmentsProperty); }
            set { SetValue(AppointmentsProperty, value); }
        }

        static MonthViewCalendar()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(MonthViewCalendar), new FrameworkPropertyMetadata(typeof(MonthViewCalendar)));
        }

        public MonthViewCalendar()
            : base()
        {
            if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(this))
            {
                //my code here..
            }
        }
        protected override void OnMouseDoubleClick(MouseButtonEventArgs e)
        {
            base.OnMouseDoubleClick(e);
            if (addingApp == true)
            {
                FrameworkElement element = e.OriginalSource as FrameworkElement;
                if (element.DataContext is DateTime)
                {
                    AppointmentWindow appointmentWindow = new AppointmentWindow
                    (
                        (Appointment appointment) =>
                        {
                            Appointments.Add(appointment);
                            if (PropertyChanged != null)
                            {
                                PropertyChanged(this, new PropertyChangedEventArgs("Appointments"));
                            }
                        }
                    );
                    appointmentWindow.Show();

                }
            }
            else
            {
                if (this.SelectedDate != null)
                {
                    // something goes here
                     
                }
            }
        }


        static public System.Drawing.Font BoldFont(System.Drawing.Font font, string result)
        {
            if (font != null)
            {
                System.Drawing.FontStyle fontStyle = font.Style;
                if (result == "bold")
                {
                    if ((fontStyle & System.Drawing.FontStyle.Bold) == 0)
                    {
                        fontStyle |= System.Drawing.FontStyle.Bold;
                        font = new Font(font, fontStyle);
                    }
                }
                else if (result == "underline")
                {
                    if ((fontStyle & System.Drawing.FontStyle.Underline) == 0)
                    {
                        fontStyle |= System.Drawing.FontStyle.Underline;
                        font = new Font(font, fontStyle);
                    }
                }
                else if (result == "italic")
                {
                    if ((fontStyle & System.Drawing.FontStyle.Italic) == 0)
                    {
                        fontStyle |= System.Drawing.FontStyle.Italic;
                        font = new Font(font, fontStyle);
                    }
                }
                else if (result == "strikeout")
                {
                    if ((fontStyle & System.Drawing.FontStyle.Strikeout) == 0)
                    {
                        fontStyle |= System.Drawing.FontStyle.Strikeout;
                        font = new Font(font, fontStyle);
                    }
                }
                else if (result == "regular")
                {
                    if ((fontStyle & System.Drawing.FontStyle.Regular) == 0)
                    {
                        fontStyle |= System.Drawing.FontStyle.Regular;
                        font = new Font(font, fontStyle);
                    }
                }
            }
            return font;
        }

        private void MenuItemClickHandlerEdit(object sender, EventArgs e)
        {
            / // something goes here
        }



            EditAppointmentWindow editappointmentWindow = new EditAppointmentWindow
            (
                (Appointment appointment) =>
                {
                    Appointments.Add(appointment);
                    //MessageBox.Show("Added Succsefully!");
                    Event_ReloadEvents();
                    if (PropertyChanged != null)
                    {
                        PropertyChanged(this, new PropertyChangedEventArgs("Appointments"));
                        Event_ReloadEvents();
                    }
                }
            ,title,type,date,time,dhifut,assignedto,discription,EventId);
            editappointmentWindow.Show();
            editappointmentWindow.Focus();
        }

        private void MenuItemClickHandlerShow(object sender, EventArgs e)
        {
            System.Windows.Forms.ToolStripMenuItem clickedItem = (System.Windows.Forms.ToolStripMenuItem)sender;
            MessageBox.Show("Show eventID: " + clickedItem.Tag.ToString());
        }

        private void MenuItemClickHandlerDelete(object sender, EventArgs e)
        {
             // something goes here

        }

        private void MenuClickHandlerDeleteAll(object sender, EventArgs e)
        {
            System.Windows.Forms.ToolStripMenuItem clickedItem = (System.Windows.Forms.ToolStripMenuItem)sender;
            // Take some action based on the data in clickedItem
            Event_DeleteAllEvents();
        }

        public void Event_ReloadEvents()
        {
            System.Windows.Forms.Form tF = new System.Windows.Forms.Form();
            foreach (System.Windows.Forms.Form S in System.Windows.Forms.Application.OpenForms)
            {
                if (S is Form1)
                {
                    tF = S;
                    S.Hide();
                    HiddingForm = true;
                }
            }
            if (HiddingForm == true)
            {
                //tF.Close();
                //tF.Dispose();
                new Form1().Show();
            }
        }

        public void Event_DeleteAllEvents()
        {
            DateTime d = ConvertDateExtoDate(this.SelectedDate.ToString());

            // something goes here
        }


        public void Event_CreateNewAppointment()
        {
             // something goes here
        }
    }
}
</appointment></appointment></appointment>

If I goes to the design view, it trows me the error I mentioned, and selects the line <local:monthviewcalendar xmlns:local="#unknown">.

I can't compile the application and can't set the child of the element host to my UserControll.

I even tried to uncomment all the lines witch I wrote "code here" or "something goes here", witch were extremely long and I thought it has something to do with it, but still - no answer for me.

Anyone knows whats the big deal?

Hope for a quick answer,
Tom

[Modifed: switched the triple backslashes to doubles because it was screwing up the colors]

Posted 3-Jan-11 8:02am

TomNidi

Updated 3-Jan-11 8:25am

William Winner

v2

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Comments

William Winner 3-Jan-11 14:28pm

What exactly does the error message say? (are there any inner messages?) And what line does it say the message is for?

And are you just trying to make things more complicated? What's with the
if ((fontstyle & System.Drawing.FontStyle.Bold) == 0)?

What's wrong with
if (font.Style != FontStyle.Bold)?

That's, IMO, a lot more readable.

[no name] 3-Jan-11 15:37pm

A good case for the use of source control

TomNidi 3-Jan-11 15:43pm

I know these code is not the best, but I don't have a problem with it right now.
When I go the the designer in order to view the code of the control, it doesn't show me the usercontrol and underlines the line "< local:MonthViewCalendar/>" with the error "Could not create an instance of type MonthViewCalendar".

Sergey Alexandrovich Kryukov 3-Jan-11 20:09pm

Why not "local:MonthViewCalendar" but "local:monthviewcalendar" -- all low-case?

TomNidi 4-Jan-11 2:36am

I didn't get your question, sorry for not understanding - my english is not that good.

jerrykid 4-Jan-11 4:53am

I think the code
if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(this))
{
//my code here..
}

is cause to error when loading. because, when creating constructor (instantiate object) you do some codes when instantiation is not complete. Try to comment this section code

TomNidi 4-Jan-11 8:13am

Well, I tried to commment everything except of the Public itself, and I got alot of wierd lookikng errors:
Title: An Unhandled Exception has occurred:
"Object reference not set to an instance of an object.
at CustomCalendar.AppointmentsConverter.Convert(Object[] values, Type targetType, Object parameter, CultureInfo culture) in C:\Users\Tom\Desktop\MyCalendar\CustomCalendar\CustomCalendar\AppointmentsConverter.cs:line 23
at System.Windows.Data.MultiBindingExpression.TransferValue()
at System.Windows.Data.MultiBindingExpression.Transfer()
at System.Windows.Data.MultiBindingExpression.UpdateTarget(Boolean includeInnerBindings)
at System.Windows.Data.MultiBindingExpression.AttachToContext(Boolean lastChance)
at System.Windows.Data.MultiBindingExpression.MS.Internal.Data.IDataBindEngineClient.AttachToContext(Boolean lastChance)
at MS.Internal.Data.DataBindEngine.Task.Run(Boolean lastChance)
at MS.Internal.Data.DataBindEngine.Run(Object arg)
at MS.Internal.Data.DataBindEngine.OnLayoutUpdated(Object sender, EventArgs e)
at System.Windows.ContextLayoutManager.fireLayoutUpdateEvent()
at System.Windows.ContextLayoutManager.UpdateLayout()
at System.Windows.UIElement.UpdateLayout()
at System.Windows.Interop.HwndSource.SetLayoutSize()
at System.Windows.Interop.HwndSource.set_RootVisualInternal(Visual value)
at System.Windows.Interop.HwndSource.set_RootVisual(Visual value)
at MS.Internal.Designer.VSIsolatedDesigner.ViewHolder.Initialize()
at MS.Internal.Designer.VSIsolatedDesigner.ViewHolder..ctor(UIElement content)
at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.get_ViewHandle()
at MS.Internal.Host.Isolation.IsolatedView.get_ViewHandle()
at MS.Internal.Designer.DesignerPane.LoadDesignerView()"

Wow.... What else?

Pawel Gielmuda 4-Jan-11 8:23am

You have reason here. Exception is thrown in AppointmentsConverter.cs line 23
Probably you are doing there something with null object

TomNidi 4-Jan-11 8:31am

This is all I got in AppointmentsConverter.cs:

public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
DateTime date = (DateTime)values[1];

ObservableCollection<Appointment> appointments = new ObservableCollection<Appointment>();
foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0])
{
if (appointment.Date.Date == date)
{
appointments.Add(appointment);
}
}

return appointments;
}

public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}

Maybe the problem is with the "return appointments"? If so, what should I do in order to fix it?

TomNidi 4-Jan-11 11:25am

The problem is probbably with the line "foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0])", but I don't know how to fix it.

It seems that there is a null object witch I take actions on.

Pawel Gielmuda 4-Jan-11 16:01pm

Add at the begining of Convert something like this to check if values are null or empty
if(values == null || values.Length < 2) return null;
this should help

TomNidi 4-Jan-11 16:46pm

public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (values == null || values.Length < 2) return null;
DateTime date = (DateTime)values[1];

ObservableCollection<Appointment> appointments = new ObservableCollection<Appointment>();
foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0])
{
if (appointment.Date.Date == date)
{
appointments.Add(appointment);
}
}
return appointments;
}

Still getting the same error...
Only when I delete the whole part inside of the public it shows me the user control with no problems at all, but still - I can not uncomment the code witch I commented at the begging in order to avoid errors, this is my main program code, with is in the MonthViewCalendar constructor public.

Pawel Gielmuda 5-Jan-11 5:06am

Can you post new exception you get?

TomNidi 5-Jan-11 5:14am

Well, I think its the same error:
at CustomCalendar.AppointmentsConverter.Convert(Object[] values, Type targetType, Object parameter, CultureInfo culture) in C:\Users\Tom\Desktop\MyCalendar\CustomCalendar\CustomCalendar\AppointmentsConverter.cs:line 25
at System.Windows.Data.MultiBindingExpression.TransferValue()
at System.Windows.Data.MultiBindingExpression.Transfer()
at System.Windows.Data.MultiBindingExpression.UpdateTarget(Boolean includeInnerBindings)
at System.Windows.Data.MultiBindingExpression.AttachToContext(Boolean lastChance)
at System.Windows.Data.MultiBindingExpression.MS.Internal.Data.IDataBindEngineClient.AttachToContext(Boolean lastChance)
at MS.Internal.Data.DataBindEngine.Task.Run(Boolean lastChance)
at MS.Internal.Data.DataBindEngine.Run(Object arg)
at MS.Internal.Data.DataBindEngine.OnLayoutUpdated(Object sender, EventArgs e)
at System.Windows.ContextLayoutManager.fireLayoutUpdateEvent()
at System.Windows.ContextLayoutManager.UpdateLayout()
at System.Windows.UIElement.UpdateLayout()
at System.Windows.Interop.HwndSource.SetLayoutSize()
at System.Windows.Interop.HwndSource.set_RootVisualInternal(Visual value)
at System.Windows.Interop.HwndSource.set_RootVisual(Visual value)
at MS.Internal.Designer.VSIsolatedDesigner.ViewHolder.Initialize()
at MS.Internal.Designer.VSIsolatedDesigner.ViewHolder..ctor(UIElement content)
at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.get_ViewHandle()
at MS.Internal.Host.Isolation.IsolatedView.get_ViewHandle()
at MS.Internal.Designer.DesignerPane.LoadDesignerView()

If I uncomment my code I don't get this error, only the message that I mentioned on the tittle of the topic, and the designer doesn't show anything

Pawel Gielmuda 5-Jan-11 5:53am

And what line is line 25 in AppointmentsConverter.cs?

TomNidi 5-Jan-11 6:02am

foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0])

Same error line as before.

TomNidi 5-Jan-11 6:41am

Well, I think I have just understood why this kept happening to me.. but I still don't know how to fix it.
The problem was in those lines in MonthViewCalendar.cs:

ap = new Appointment();
ap.Subject = reader["name"].ToString();
//
DateTime d = new DateTime();
int days = getDate(reader["date"].ToString(), "day");
int months = getDate(reader["date"].ToString(), "month");
int years = getDate(reader["date"].ToString(), "year");
d = d.AddYears(years - 1);
d = d.AddMonths(months - 1);
d = d.AddDays(days - 1);
ap.Date = d;
//
ap.Time = reader["startTime"].ToString();
ap.Dhifut = reader["dhifut"].ToString();
ap.AssignedFor = reader["assignedTo"].ToString();
ap.Type = reader["type"].ToString(); ;
ap.Description = reader["description"].ToString();
Appointments.Add(ap);

This is the GetDate function:

public int getDate(string date, string type)
{
string[] types = date.Split('/');
if (type == "day")
return Int32.Parse(types[0]);
else if (type == "month")
return Int32.Parse(types[1]);
else // type == year
return Int32.Parse(types[2]);
}

I still don't know why the designer won't load when I call this function.. the Date witch is stored in the Database witch I call the function on looks like this: "Days/Months/Years" - for example: "04/01/2011"
Do you know why this function keep causing me this problem?

TomNidi 5-Jan-11 6:55am

Edit: The problem is in the "years" section, for example if I type "2011" instead of the "years" word in " d = d.AddYears(years - 1);", the problem is disapear, but I still can not set the child of my element host to the usercontrol. If I do it by the properties, the Visual Stuid crashes. If I do it by code, I get the error: "Object reference not set to an instance of an object.". and it yellows me the line I mention before - "foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0])". Its like I changed something in it, witch I didn't..

3 solutions

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Pawel Gielmuda · Answer 1 · 2011-01-03T22:35:00

Solution 1

You can try to put

try 
{
   //user control stuff here 
}
catch(Exception ex)
{
    MessageBox.Show(ex.ToString());
}

In constructor of the user control or in constructor of the parent window. It should give you some more information about what is wrong

Posted 3-Jan-11 22:35pm

Pawel Gielmuda

Comments

TomNidi 4-Jan-11 8:05am

I didn't get where should I put it. What is the constructor?
Anyway, even if I put it I'm not able to set the child of my element host to the user control, and therefore I can not make the code start.

Can you explain a little bit more? Thank you.

Pawel Gielmuda 4-Jan-11 8:24am

Please read my other comment above

TomNidi 4-Jan-11 8:47am

Already read, waiting for a new answer.

Vinayak P Kamath · Answer 2 · 2011-01-03T22:59:00

Solution 2

1)The tag close of the User control!! Is it jjuts a typo??

2) Remove ths xmlns:local attribute from the Calendar control tag.

Posted 3-Jan-11 22:59pm

Vinayak P Kamath

Updated 3-Jan-11 23:00pm

v2

Comments

TomNidi 4-Jan-11 8:09am

I can not remove anything from the list you have mentioned.
If I remove the tag close from the line " < local:MonthViewCalendar/> ", it throws me the next error: "Closing tag for element '<local:monthviewcalendar>' was not found.".
If I remove the xmlns:local line, it shows me the error: "The type 'local:MonthViewCalendar' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built ".

None of the rebuilds actually helped.

What shell I do?

Pawel Gielmuda · Answer 3 · 2011-01-05T02:17:00

The exception in

foreach (Appointment appointment in (ObservableCollection<Appointment>)values[0]

might be thrown because values cannot be converted to ObservableCollection.
Try to do something like that:

public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
{ 
try {
   if (values == null || values.Length < 2) 
      return null;
   DateTime date = (DateTime)values[1];
   ObservableCollection<Appointment> appointments = new ObservableCollection<Appointment>();
   foreach (Appointment appointment in ObservableCollection<Appointment>)values[0]) 
   { 
      if (appointment.Date.Date == date) 
         { appointments.Add(appointment); } 
   }
 return appointments;
 }
catch(Exception ex) { return null; }

 }

Maybe thats not the best way to handle it but should get rid of the exception.

The problem in GetDate function might be caused by wrong input data at design time. You expect exact string DD/MM/YYYY and don't handle if it doesn't meet the format. You can add try catch too here or use better validation method

Could not create an instance of type

3 solutions

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