Develop Reference

Button click event not responding c#

The problem we are having is accessing the click event for a button which is created in the click event of another button i.e. clicking the first button generates a new panel and controls, and we now want the button on this newly created panel to perform an action.
The controls have been declared at the top of the class as follows:
Panel createElementPage = null;
TextBox elementDescription = null;
TextBox elementName = null;
Button continueButton = null;
AuditSystem audit;
Here is an excerpt of the method that generates the new panel, the part that defines the continueButton is written as follows:
public void CE_Click(object sender, EventArgs e)
{
createElementPage.Controls.Add(elementDescription);
continueButton = new Button();
continueButton.Text = "Continue";
continueButton.Location = new Point(700, 500);
continueButton.Size = new Size(100, 50);
createElementPage.Controls.Add(continueButton);
}
We want to access the continueButton's click event handler but the method we have written does not seem to be working. This is what we have so far:
private void continueButton_Click(object sender, EventArgs e)
{
Console.WriteLine(" something");
}
Clicking the button yields no results, and we have tried a few solutions such as implementing a seperate eventHandler method. Does anybody have a fix for this?

You have to actually subscribe to the event:
continueButton.Click += continueButton_Click;
Events need to be told what they should handle. Without that, they won't "listen" to anything.
Friendly note: be careful when adding handlers "on demand" like this (i.e. outside of the designer). It doesn't really apply here (you have a new button each time), but it's fairly easy to accidentally subscribe to a control's event multiple times, and your handler will fire multiple times as a result. It's just nice to be aware of :)

check whether a button in another window is clicked

I want to open a window if a button is clicked, and that button is located in another window.
So how to check whether a button in another window is clicked or not?
Now I am coding in a class called 'RightButton.cs'
I want to open a window called 'PopUp' when 'Add' button in 'Reason' window is clicked.
PaidOutReason paid = new PaidOutReason(trnprt, apiParameters);
paid.ShowDialog();
if (paid.btnSave.ClickMode == new ClickMode())
{
PopUpBanks popu = new PopUpBanks(this);
popu.Show();
}
This one was working perfectly, but I had to remove ShowDialog() and replace it with Show(). Then it was not working.
This is for a POS system. It has a user Control called 'Keyboard'. When the 'Reason' window is opening this Keyboard also want to be opened. Therefore I had to replace ShowDialog() with Show().

I'd add an event to the window, and bind an event handler to it.
class WndWindow{
BtnPaid_Click(object sender, EventArgs e){
using(var paid = new PaidOutReason()){
paid.BtnAddClick += Paid_BtnAddClick;
paid.ShowDialog();
paid.BtnAddClick -= Paid_BtnAddClick;
}
}
Paid_BtnAddClick(object sender, EventArgs e){
var popu = new PopUpBanks();
popu.Show();
}
}
class PaidOutReason{
public event EventHandler BtnAddClick;
BtnAdd_Click(object sender, EventArgs e){
//Do standard event handler code
BtnAddClick?.Invoke(this, e);
}
}
If there's any sort of checks you need to perform you can do that before reading the event, and simply return if checks fail.

You can use static controlls in your app. Start with declaring static window object in App.xaml.cs, for example
public static PaidOutReason paidOutWindow;
then, in App constructor method, after InitializingComponent(), initialize static window class:
paidOutWindow = new PaidOutReason();
You may wonder what it gives to you. Since it's POS application, you are likely to use the same set of windows quite often and repeatedly, means you can hold window object in memory and refer to it (and change, when needed). Also, after doing such thing, you will have access to all structures inside PaidOutReason object, by typing
App.paidOutWindow.FunctionName();
and finally, you should have access to all window functions such as ShowDialog().

If you are using MVVM pattern, then you can use command binding for showing the PopupBanks window.
For example:
public class ViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public ICommand AddCommand { get; set; }
public ViewModel()
{
AddCommand = new RelayCommand(AddCommandHandler);
}
private void AddCommandHandler()
{
IPopUpBanks popu = new PopUpBanks(this);
popu.Show();
}
}
PaidOutReason view:
1. <Button x:Name="Add" Command={Binding AddCommand}/>
2. Set the above viewmodel as datacontext of PaidOutReason view.
Create a interface IPopUpBanks containing Show() method and implement this interface on PopUpBanks view.

Handle the Click event of btnSave:
PaidOutReason paid = new PaidOutReason(trnprt, apiParameters);
paid.btnSave.Click += (ss, ee) =>
{
PopUpBanks popu = new PopUpBanks(this);
popu.Show();
};
paid.Show();

Instead of the Keyboard Window, I made it a user control and then initialized an event in there. Then I insert that Keyboard User Control to the PaidOutReason Window and then called the event. Then I was able to use ShowDialog() to call the window.

C# Passing control reference to another form

I have a button and hidden textbox on my main form. When I press the button it will hide the main form and show the second form. When I press the button on the second form I want to show the main form again but this time I need to show the hidden textbox. I know how to pass the text from a textbox to another form but not just the reference of the textbox.

You better pass the complete main form instance for the second form, and create a public function to set the textbox to visible, or create a property around it.
Something like:
//form1
Form2 second = new Form2(this);
}....
public void ShowTextBox()
{
textbox1.Visible=true;
}
//form2
Form parent;
public Form2(Form _parent)
{
parent=_parent;
}
///later
parent.Show();
parent.ShowTextBox();

Sounds to me like a custom event would be a better approach. Have the secondary form expose an event, which is raised at whatever appropriate time (your button press). In your main form, when you create your instance of your second form, subscribe to that event. Then run your "unhide" code from within the mainform's event subscription.
This keeps the coupling down on the two forms and results in much more easily maintainable and extensible code (for best effect, use interfaces, but events are a good middle ground for learning).
Something like this:
(it's been a long time since I worked with winforms, or events even, so if this needs refining let me know)
// your secondary/popup form's class
public partial class Form2 : Form
{
// add a custom event
public EventHandler<EventArgs> MyCustomEvent;
// link up your button click event
void InitializeComponent() {
myButton.Click += myButtonClick;
}
// when your button is clicked, raise your custom event
void myButtonClick(object sender, EventArgs, e) {
onMyCustomEvent();
}
// this "broadcasts" the event
void onMyCustomEvent() {
EventHandler<EventArgs> h = MyCustomEvent;
if (h != null) {
h(this, new EventArgs());
}
}
}
// your main form's class
public partial class MainForm
{
void InitializeComponent() {
// ...
}
void showForm2() {
var form2 = new Form2();
form2.MyCustomEvent += form2CustomEvent;
form2.Show();
}
void form2CustomEvent(object sender, EventArgs e) {
myHiddenTextBox.Visible = true;
}
}
All in all this is a much better approach in terms of code architecture. Now the popup doesn't care who opens it (it has no reference to the main form), and the custom event (which is really what you're after) can be managed to any level of control you need, without interfering how other thing work (for example, perhaps later you may want to have a different action that fires this same custom event...)
Food for thought.

Windows Forms - get Text value from object of type button

I have a Windows form named Form1 and panel within this form named panel1. I use the panel only to place buttons there so that I can group them and work with them separately from the other buttons in my Form1. For the purpose of my program I need to handle every button click made from the buttons inside panel1. For this purpose I use the same code snippet:
public Form1()
{
InitializeComponent();
// Set a click event handler for the button in the panel
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += HandleClick;
}
}
What I need to do is to have a way to identify which button exactly has been clicked. For this purpose I played a little bit with my handler method:
private void HandleClick(object o, EventArgs e)
{
MessageBox.Show("HI" + o.ToString());
}
which gave me some hope because I get this:
It's the second part - Text: button4 which is actually enough information to continue with my work. But I can't find a way to get this piece of information without some complicated string manipulations. So is there a way to get this or other unique information about the button been clicked given the way I have written my code?

private void HandleClick(object sender, EventArgs e)
{
var btn = sender as Button;
if (btn != null)
{
MessageBox.Show(btn.Text);
}
}

One option is to cast the object to a Button, but rather than doing the casting you can change how the event handler is assigned so that you don't need to cast in the first place:
foreach (var button in panel1.Controls.OfType<Button>())
{
button.Click += (_,args)=> HandleClick(button, args);
}
Then just change the signature of HandleClick to:
private void HandleClick(Button button, EventArgs e);

You need to cast sender to the Button class so you can access its properties:
Button b = (Button)sender;
MessageBox.Show(b.Text);

C# asp.net Button_Click event handler not working

I have a webusercontrol with a few controls on it like some labels,a textbox and eventually a button. The purpose of this control is to add it to my main page in a placeholder every time I click on the button on the webusercontrol.
This is the code behind my button on my webcontrol
protected void btnCriteriaToevoegen_Click(object sender, EventArgs e)
{
//New eventhandler == all of the eventhandlers of all the objects who have subscribed to the event.
EventHandler eventhandler = ButtonDoorgaan;
ButtonOpslaanEvent mijnevent = new ButtonOpslaanEvent();
//Basic variables I will give with my costum event(ButtonOpslaanEvent)
mijnevent.Naam = txtCriteriumNaam.Text;
mijnevent.Score = Convert.ToInt16(DdlCriteriumScoreSchaal.SelectedValue);
int weging = Convert.ToInt16(DdlCriteriumWeging.SelectedValue) - 1;
mijnevent.Weging = Convert.ToInt16(weging);
//If the eventhandler is not null, for every object that has an eventhandler, execute it.
if(eventhandler!=null)
eventhandler(sender, mijnevent);
}
The eventhandler that need to be executed when the event is fired is defined in my main page like this :
private void critlijn_ButtonDoorgaan(object sender, EventArgs e)
{
ButtonOpslaanEvent eigenevent = (ButtonOpslaanEvent)e;
IEnumerator<Domein> domeinenumerator = domeinen.GetEnumerator();
while (domeinenumerator.MoveNext())
{
if (domeinenumerator.Current.DomeinNaam.Equals(lijstdomeinitemgeselecteerd))
{
Criterium nieuwcriterium = new Criterium();
nieuwcriterium.CriteriumNaam = eigenevent.Naam;
nieuwcriterium.CriteriumScore = Convert.ToString(eigenevent.Score);
nieuwcriterium.CriteriumWeging = Convert.ToString(eigenevent.Weging);
domeinenumerator.Current.Criteriums.Add(nieuwcriterium);
}
}
btnCriteriaToevoegen_Click(sender, e);
}
The btnCriteriaToevoegen_Click event fires and then calls this method(addCriteriaButton()), which will add the button onto the placeholder in my main page:
private void addCriteriaButton()
{
Criterialijn criterialijn = (Criterialijn)LoadControl("~/Criterialijn.ascx");
//Add eventhandlers to control
criterialijn.ButtonDoorgaan += new EventHandler(critlijn_ButtonDoorgaan);
criterialijn.Aangevinkt += new EventHandler(critlijn_Aangevinkt);
//Every control on the page except this one, not enabled
IEnumerator<Criterialijn> criterialijnenumerator = criteriacontrols.GetEnumerator();
while (criterialijnenumerator.MoveNext())
{
criterialijnenumerator.Current.Enabled = false;
}
//Add it to a list of webusercontrols that are currently on screen
criteriacontrols.Add(criterialijn);
criterialijn.Enabled = true;
//Add to placeholder
plhCriteria.Controls.Add(criterialijn);
}
So when all this is said and done, and I run my program, he adds the control to my placeholder, but when I click on the button, he does not add a new control to my placeholder, and just clears my placeholder for some reason. Normally everything should be fine, but I have tried to see if he actually fires the event when you click on the button, and he does not. I have tried to give you a sample of my code, because the code of the whole page is quite big and that would not help you at all. Any ideas why he is not firing the event of the button?

So when your button that you dynamically added posts back, a new page instance is created and that button no longer exists (since you only added it on the previous button click), it has not been recreated.
You must re-create dynamic controls on each postback
Remeber, a new instance of the Page class is created for each postback, any previously created controls, event handlers will not exists in the new instance unless you explicitly re-create them.

I assume these Criteria are some sort of tree structure the user can navigate through (and hopefully arriving at the end somewhere ?).
About btnCriteriaToevoegen_Click:
Why are you defining an event inside a method?
In critlijn_ButtonDoorgaan and addCriteriaButton:
Instead of using an enumerator, just use
foreach(var control in criteriacontrols)
control.Enabled = false;
So yeah, fair to say it's still not quite comprehensable, but it least I tried right? :)
EDIT
ok, then I have this question:
The eventhandler that need to be
executed when the event is fired is
defined in my main page like this :
How sure are you that, when you do
EventHandler eventhandler = ButtonDoorgaan;
the variable "eventhandler" gets all eventhandlers attached to ButtonDoorgaan ?
EDIT 2 (the return)
See Richard Friend's answer; your control is not there anymore