Handle An Object's Object Property Changed Event In .NET Windows Forms?

Jun 7, 2012

I know how to handle a single objects property changed event very easily. I want to handle a objects property changed event that is part of another object.

Given Object:

[ObjectY = Y]
+ Public WithEvents X As ObjectX

I would like to do something like:

Private Sub XPropertyChanged() Handles Y.X.PropertyChanged

Right now I need to create a object that equals the object inside that object and then handle this variable pointers property changed, but that is just annoying.

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Handle A Property As An Object?

Oct 20, 2011

Is it possible to handle a property as an object?I want to reach a property as an object , not through its owner.

Dim prop as object = UNKNOWN_FUNC(btnTest.Text)
prop = "New text of btnText.Text" '

I want to modify Text property of btnTest by this way..

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Custom DataGridViewColumn - Error: 'Public Event ItemCheck(sender As Object, E As System.Windows.Forms.ItemCheckEventArgs)'

Jan 19, 2012

following code from c# to visual basic, and I'm coming up with the following error: 'Public Event ItemCheck(sender As Object, e As System.Windows.Forms.ItemCheckEventArgs)' as an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event.

[Code]...

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VS 2008 Handle Same Event For All Of That Object Type?

Sep 12, 2009

Say I have a button that creates more buttons with a random .Text property, and placed them on the form in different locations. And since these buttons are being created at runtime, I want to be able to have an event handler for all button controls on the form that makes the form's text the same as the sender's text.

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Get An Object To Listen For Its Property's Event?

Dec 15, 2009

I have an object of type SomeObject, with an event StatusChanged. I have a property in SomeObject of type Status also with an event StatusChanged. Within a private function in SomeObject, I would like to run some logic (including firing the StatusChanged event) in the event that Status has fired its StatusChanged event. I have been away from events for a while so it's a bit cloudy to me. How do I do this?

I'm writing in ASP.NET/VB.NET EDIT Ok, in the event that I can't do the above, how would I get the outer object (SomeObject) to fire its StatusChanged event when the inner object (Status) fires its StatusChanged event?

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How To Attach An Event To Object Property?

Nov 1, 2010

I tried to make a custom form, inherited from systems.windows.forms.form object.

I just put one custom property named FormMode.When this property's values changed, it automatically raise an event.

Public class ucForm
inherits system.windows.forms.form
Public Enum FormModeEnum

[Code]...

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Forms :: Object Property Change In Combobox?

Apr 7, 2010

I am working on a project that uses lots of custom class objects.Before starting work on real project, I tested the object behaviour on a temporary project. And find that if i add the object to a list and combobox and then make any change to the object property then it reflects in list and combobox.But after using the same process in real project the change does not reflect. Why?Also, how can i update object property placed in the combobox.

for eg.
Class X has property id and name
created objX of type Class X and set id=1 and name='All'

[code].....

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Get Object Reference From Object Handle

May 30, 2011

Is there any way to get reference of an object by its handle that obtained through FindWindowEx API?
this object is a user control written in .net.

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.net - Object Reference Not Set To An Instance Of An Object: Child Property?

Nov 21, 2011

I'm checking If a border's child property is not set to nothing or equal to a given element, but whenever I run the program, it says that it's set to nothing and crashes. Here's my code:

If Not Me.Child.Equals(Nothing) Then ...
If Me.Child.Equals(value) Then ...

Both gives an error. What should I do to pass these lines? Also in C# it would look like this:

if(this.Child != null) ...
if (this.Child != value) ...

But this time it doesn't give an error.

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C# - Why Is Attached Property Property Changed Event Only Firing One Time

Nov 27, 2010

I have a listbox binded to a list of objects. For each list item I wanted to have a rectangle whose fill color is determined by a few properties of the binded object. So I did the following:

Made sure INotifyPropertyChanged was implemented on my object.Created a class to expose the properties I am interested in as attached properties.Binded the properties of the object to the attached properties of the rectangle Created a style that uses triggers to set the rectangle fill based on attached properties.

This works, but only the first time the property of the object changes. After that, the attached properties do not seem to be receiving notification when the data object's property changes. I have double checked and my data object is raising the INotifyPropertyChanged event.

<Rectangle Style="{StaticResource RecordStateRectangleStyle}"
Width="10" Height="10" Stroke="Black"
local:RecordAttachment.RecordState="{Binding Path=RecordState}"
local:RecordAttachment.IsDeleted="{Binding Path=IsDeleted}" />

[code]....

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Object Scope - Lose The Object In Selected Date Change Event In Calendar

Oct 18, 2010

If I declare my object at the beggining of my page class, and instantiate it in a dropdownlist selected_index change event. Shouldn't this object be available thru out the entire page and also persist thru a postback? I lose the object in my selected date change event in my calendar.

[Code]...

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Event Handler Code Cause A Object Reference Not Set To An Instance Of An Object. Error (only Present On Live Server, Ok On Dev)?

Mar 4, 2010

Here is the code for the button click event;

Protected Sub CompetenciesButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles CompetenciesButton.Click
Dim con As String = WebConfigurationManager.ConnectionStrings("foo").ToString()

[code].....

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Forms :: Enable E.keyvalue Event When A Player Hits An Object?

Apr 29, 2011

im looking for some code that can enable a e.keyvalue event when a player hits an object on form but i also want the form to load with the e.keyvalue event disabled

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Windows - Access The My.Application Object From A Form Or Control Object?

Jul 6, 2011

I have a solution with several Projects in it. There is a Windows App project (called ImportClient), and a Class Library (Import.Library). The Import.Library has functions to perform data imports (I have other applications in the solution that also need to call it). But the interactive application, I want to be able to pass in some form controls, and have it update the GUI. No problem. But, I also want to execute a DoEvents() so that the loop execution doesn't hang other interaction to the app.

So, ImportClient has a reference to Import.Library. But I can't add a reference to ImportClient to the Import.Library, because the compiler complains about circular reference, etc. I don't know how else to define the My.Application object of ImportClient as a parameter to the data function in ImportLibrary.

(I realize this is a dumb question - problem is, for this project I have a tight timeline, and haven't learned how to do the BackgroundWorker process. If you think I could pick it up quickly, I'm open to some hints about how to update the progress bar on the GUI, and how to pause / cancel the background task.)

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Windows Forms Application That Incorporates The WebBrowser Object?

Mar 24, 2010

I have a VB.Net Windows Forms application that incorporates the WebBrowser object.I want to place the input focus/cursor in a textbox after successfully loading a PDF document in the WebBrowser via the Navigate method.I tried to set the focus (TextBox1.Focus) in the DocumentCompleted event handler, but that failed.Or, I should say that the focus does not stay in the textbox.It appears that all processing initiated by the Navigate method is not complete even when the DocumentCompleted event is fired.And, as a result, the input focus is being moved from the textbox for some reason.

I now set the input focus in the ProgressChanged event handler when the CurrentProgress and MaximumProgress event agruments both have values of zero.This is successful, but I want to be sure that I can rely on the values of the event arguments.After I use the Navigate method, the ProgressChanged event is fired 4 times with the following CurrentProgress and MaximumProgress event argument values: 0 of 10000, 10000 of 10000, 10000 of 10000 (again), and finally 0 of 0.Can I confidently rely on a ProgressChanged event at the absolute end of a successful WebBrowser navigation that has CurrentProgress and MaximumProgress both set to 0?

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.net Windows Form, Object Reference Not Set To An Instance Of An Object?

Apr 27, 2010

I am getting this error "Object reference not set to an instance of an object" and I dont know where/how to fix it and it does not tell me where the error in the code occurs, just a pop-up windows saying the error. Here is the code on the "start up" Windows form..

[Code]...

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VS 2010 "Object Reference" Error When Adding Object To List (Of T) Property

Apr 25, 2011

I have a class that has a property that I declare like this:

VB.NET
Private _DirectoryList As List(Of FileDirectoryInfo) ''' <summary> ''' Array of directories. ''' </summary> ''' <value>Object</value> ''' <returns>Directory array list</returns> ''' <remarks>N/A</remarks> Public Property Directory As List(Of FileDirectoryInfo) Get Return _DirectoryList End Get Set(ByVal value As List(Of FileDirectoryInfo)) _DirectoryList = value End Set End Property

[Code]...

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Variable/property Changed Event In .net?

Jan 3, 2010

How can I make an event that is raised when a variable or property is changed (or can I just put the code I would put in an event in the Set section of a property?

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Unable To Cast Object Of Type 'System.Windows.Forms.Button' To Type 'System.Windows.Forms.TextBox'

Apr 28, 2009

I have a panel with some controls in it (several textboxes, a slider, 2 buttons, and a small groupbox).. When I click a button, I want all of the textboxes within the panel to be readonly... So I have this code: [code] When I run it though, I get the following error:Unable to cast object of type 'System.Windows.Forms.Button' to type 'System.Windows.Forms.TextBox'.If I remove a button, it moves on to give me the same error but for a label..

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Compare An Object Property To Another Object Property?

Jul 4, 2011

I have a listbox of a object called Account, which has 2 fields, password, and username. How can I compare a New Account to all the accounts in the list and see if the password matches?

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Forms :: Object Reference Not Set To An Instance Of An Object?

Aug 24, 2009

Our customers get an unahndled exception as stated above. Can you tell me how to trap the error on customer applicaiton? Customer does not know when the error comes so i want to know what causes the error.

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Unable To Cast Object Of Type System.Windows.Forms.MenuStrip

Jun 12, 2011

I have a form contain 10 checkbox. how to count total checkboxes that has been checked? i search over the internet but not found any solution. please help me. i found a code, but when i apply it on my project it says "Unable to cast object of type System.Windows.Forms.MenuStrip' to type Component Factory. Krypton.Toolkit.KryptonCheckBox'".i think i have problems with Me.Controls(on the code)[code]

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List Of T Find Date Or Other Property In A Object In The List - Then Return Found Object?

Sep 3, 2009

After reading all the examples for list of T exists and Find and find first, none show how to handle multi-property objects. Below is bare bones example maybe someone could flesh out to show how this should be done.

Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim DatePriceList As New List(Of DateAndPrice)
DatePriceList.Add(New DateAndPrice(Date.Parse("1/1/2000"), 10.12))
DatePriceList.Add(New DateAndPrice(Date.Parse("1/2/2000"), 11.12))

[Code]...

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C# - Deep Copy System.Windows.Forms.WebBrowser Object/Restore State?

Apr 27, 2009

Essentially what I want to do is copy a WebBrowser object such that I can do the equivalent of "Open In New Tab" or "Open In New Window" actions, maintaining any posted data. I don't just want to navigate to the same URL as in the original WebBrowser object, rather I want to repeat the HttpWebRequest.

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Deep Clone Of Object With Base Class System.Windows.Forms.Control

Apr 18, 2012

I have an object (a third component gridview) which is serializable, and I need a deep clone of this object. I have the following code which throws the exception."The type System.Windows.Forms.Control in assembly System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKey Token=b77a5c5 61934e089 is not serializable".So the gridview's base class is System.Windows.Forms.Control, which is not serializable. How can I get a deep clone from the gridview? [code]

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Keep Two-way Binding When Whole Object Has Changed

Aug 24, 2010

I have a class:

[Code]...

Now I can change the TextBoxes or the object: MyObject.Two = 3 ..the object and TextBoxes are updated in two ways. Now I want to update the whole object: MyObject = New TestClass(3, 4) ...but this doesn't update the TextBoxes.

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VS 2008 Error - Unable To Cast Object Of Type 'System.Windows.Forms.MouseEventArgs'

Nov 7, 2009

When executing this code I get this error:

Unable to cast object of type 'System.Windows.Forms.MouseEventArgs' to type 'System.Windows.Forms.DataGridViewCellMouseEventArgs'.

Private Sub NoteGrid_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles NoteGrid.CellContentClick
Try

[code]....

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Flattening An Object Hierarchy Using A Shim Class - Initializing Derived Object Properties From The Base Object?

Jul 10, 2010

I am somewhat new to object oriented programming and am attempting to flatten a Linq object hierarchy by using a shim class.how to initalize a derived class with property values from a base class?I have two objects, a base object with about 100 properties, and a derived object which inherits from the base object and adds a few additional properties beyond those of the base object. My simple constructor creates the derived object, but I am looking for a way to initialize the derived object properties with values from the base object.Right now I am using reflection to iterate over the properties individually and I suspect there may be a better way. The following example shows my shim class constructor for the derived class, and two properties:

newProperty1 - a new string property of the derived class

flattenedProperty2 - a new string property of the derived class, copied from a 2nd-level object of the base class

Code example:

Public Class derivedObj
Inherits baseObj
Private _newProperty1 As String[code].......

Is this the correct constructor approach to flatten the object hierarchy using a shim class? My second question relates to initialization of properties in the derived class. The constructor above creates the derived object, but what is the best way to initialize the derived object properties with values from the base object? The following code uses reflection to iterate over the properties individually, but I suspect there may be a better way.

Code example:

' property names are in the string array fieldNames

'baseObjQuery is an ienumerable of baseObj

'derivedObjList is a list of derivedObj[code].....

Is there a simple way to initialize values for the properties in the derived object based upon the values of the common properties in the base object?

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VS 2005 Can't Find Where Object Name/type Is Being Set/changed

Feb 10, 2010

This starts with an object being added to a collection with: CommonArgs.Add(ObjName, Me)

ObjName is a string, call it "Obj1". Me is an instance of a class inheriting from UserControl. Call it "Class1".

Now, to check the value assigned to Obj1, the vendor has the

Dim Obj As Object = CommonArgs(ObjName)
Dim Info As System.Reflection.FieldInfo = Obj.GetType().GetField(ObjName, System.Reflection.BindingFlags.Public Or System.Reflection.BindingFlags.Instance Or System.Reflection.BindingFlags.IgnoreCase)
Obj is the Class1 object added to CommonArgs.

When I run this in my test app, Info is Nothing-but when I run it in the vendor's app Info is an Enumerated type. Why?

I've found a little more info, but it's still a mystery to me-and so far it appears to be a mystery to everybody else, too.

First, I noticed that I didn't mention that the Collection is a Hashtable. I don't know if that would make a difference, but it is something I forgot to mention.

Second, there's a 'regular' variable named ObjName that contains the value being returned by Info. My understanding is that there's no connection between these, e.g. Dim X as Integer = 1 doesn't change the type or value of the object of CommonArgs("X"). But that's what appears to be happening.

Any suggestion?

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.net - LINQ To SQL A Member Defining The Identity Of The Object Cannot Be Changed?

Nov 29, 2009

I'm writing a Generic for LINQ to SQL CUD. I

'Generic Insert
Public Shared Sub Add(Of T As Class)(ByVal entity As T)
Using db As New APIUDataContext()

[code]....

Error message from Generic Update.Value of member 'Id' of an object of type 'TestAuthor' changed.A member defining the identity of the object cannot be changed.Consider adding a new object with new identity and deleting the existing one instead.What do I need to modify the Generic Update?

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