Develop Reference

How do I retrieve a custom list from another form in a using block? [duplicate]

I have a main form (let's call it frmHireQuote) that is a child of a main MDI form (frmMainMDI), that shows another form (frmImportContact) via ShowDialog() when a button is clicked.
When the user clicks the 'OK' on frmImportContact, I want to pass a few string variables back to some text boxes on frmHireQuote.
Note that there could be multiple instances of frmHireQuote, it's obviously important that I get back to the instance that called this instance of frmImportContact.
What's the best method of doing this?

Create some public Properties on your sub-form like so
public string ReturnValue1 {get;set;}
public string ReturnValue2 {get;set;}
then set this inside your sub-form ok button click handler
private void btnOk_Click(object sender,EventArgs e)
{
this.ReturnValue1 = "Something";
this.ReturnValue2 = DateTime.Now.ToString(); //example
this.DialogResult = DialogResult.OK;
this.Close();
}
Then in your frmHireQuote form, when you open the sub-form
using (var form = new frmImportContact())
{
var result = form.ShowDialog();
if (result == DialogResult.OK)
{
string val = form.ReturnValue1; //values preserved after close
string dateString = form.ReturnValue2;
//Do something here with these values
//for example
this.txtSomething.Text = val;
}
}
Additionaly if you wish to cancel out of the sub-form you can just add a button to the form and set its DialogResult to Cancel and you can also set the CancelButton property of the form to said button - this will enable the escape key to cancel out of the form.

I normally create a static method on form/dialog, that I can call. This returns the success (OK-button) or failure, along with the values that needs to be filled in.
public class ResultFromFrmMain {
public DialogResult Result { get; set; }
public string Field1 { get; set; }
}
And on the form:
public static ResultFromFrmMain Execute() {
using (var f = new frmMain()) {
var result = new ResultFromFrmMain();
result.Result = f.ShowDialog();
if (result.Result == DialogResult.OK) {
// fill other values
}
return result;
}
}
To call your form;
public void MyEventToCallForm() {
var result = frmMain.Execute();
if (result.Result == DialogResult.OK) {
myTextBox.Text = result.Field1; // or something like that
}
}

Found another small problem with this code... or at least it was problematic when I tried to implement it.
The buttons in frmMain do not return a compatible value, using VS2010 I added the following and everything started working fine.
public static ResultFromFrmMain Execute() {
using (var f = new frmMain()) {
f.buttonOK.DialogResult = DialogResult.OK;
f.buttonCancel.DialogResult = DialogResult.Cancel;
var result = new ResultFromFrmMain();
result.Result = f.ShowDialog();
if (result.Result == DialogResult.OK) {
// fill other values
}
return result;
}
}
After adding the two button values, the dialog worked great!
Thanks for the example, it really helped.

delegates are the best option for sending data from one form to another.
public partial class frmImportContact : Form
{
public delegate void callback_data(string someData);
public event callback_data getData_CallBack;
private void button_Click(object sender, EventArgs e)
{
string myData = "Top Secret Data To Share";
getData_CallBack(myData);
}
}
public partial class frmHireQuote : Form
{
private void Button_Click(object sender, EventArgs e)
{
frmImportContact obj = new frmImportContact();
obj.getData_CallBack += getData;
}
private void getData(string someData)
{
MessageBox.Show("someData");
}
}

I just put into constructor something by reference, so the subform can change its value and main form can get new or modified object from subform.

If you want to pass data to form2 from form1 without passing like new form(sting "data");
Do like that
in form 1
using (Form2 form2= new Form2())
{
form2.ReturnValue1 = "lalala";
form2.ShowDialog();
}
in form 2 add
public string ReturnValue1 { get; set; }
private void form2_Load(object sender, EventArgs e)
{
MessageBox.Show(ReturnValue1);
}
Also you can use value in form1 like this if you want to swap something in form1
just in form1
textbox.Text =form2.ReturnValue1

I use MDI quite a lot, I like it much more (where it can be used) than multiple floating forms.
But to get the best from it you need to get to grips with your own events. It makes life so much easier for you.
A skeletal example.
Have your own interupt types,
//Clock, Stock and Accoubts represent the actual forms in
//the MDI application. When I have multiple copies of a form
//I also give them an ID, at the time they are created, then
//include that ID in the Args class.
public enum InteruptSource
{
IS_CLOCK = 0, IS_STOCKS, IS_ACCOUNTS
}
//This particular event type is time based,
//but you can add others to it, such as document
//based.
public enum EVInterupts
{
CI_NEWDAY = 0, CI_NEWMONTH, CI_NEWYEAR, CI_PAYDAY, CI_STOCKPAYOUT,
CI_STOCKIN, DO_NEWEMAIL, DO_SAVETOARCHIVE
}
Then your own Args type
public class ControlArgs
{
//MDI form source
public InteruptSource source { get; set; }
//Interrupt type
public EVInterupts clockInt { get; set; }
//in this case only a date is needed
//but normally I include optional data (as if a C UNION type)
//the form that responds to the event decides if
//the data is for it.
public DateTime date { get; set; }
//CI_STOCKIN
public StockClass inStock { get; set; }
}
Then use the delegate within your namespace, but outside of a class
namespace MyApplication
{
public delegate void StoreHandler(object sender, ControlArgs e);
public partial class Form1 : Form
{
//your main form
}
Now either manually or using the GUI, have the MDIparent respond to the events of the child forms.
But with your owr Args, you can reduce this to a single function. and you can have provision to interupt the interupts, good for debugging, but can be usefull in other ways too.
Just have al of your mdiparent event codes point to the one function,
calendar.Friday += new StoreHandler(MyEvents);
calendar.Saturday += new StoreHandler(MyEvents);
calendar.Sunday += new StoreHandler(MyEvents);
calendar.PayDay += new StoreHandler(MyEvents);
calendar.NewYear += new StoreHandler(MyEvents);
A simple switch mechanism is usually enough to pass events on to appropriate forms.

First you have to define attribute in form2(child) you will update this attribute in form2 and also from form1(parent) :
public string Response { get; set; }
private void OkButton_Click(object sender, EventArgs e)
{
Response = "ok";
}
private void CancelButton_Click(object sender, EventArgs e)
{
Response = "Cancel";
}
Calling of form2(child) from form1(parent):
using (Form2 formObject= new Form2() )
{
formObject.ShowDialog();
string result = formObject.Response;
//to update response of form2 after saving in result
formObject.Response="";
// do what ever with result...
MessageBox.Show("Response from form2: "+result);
}

I raise an event in the the form setting the value and subscribe to that event in the form(s) that need to deal with the value change.

C# How do i change a label text from another form

So i have 2 forms.
Form 1 is my main form, and form 2 is where I enter text in a textbox to be displayed on a label on form 1. Also the button to 'confirm' and actually change the entered text of my label is on form 2 which needs to stay that way.
for some reason this does not work.
Form 2 has a text-box and a button, when I press the button, it changes the string value of the designated string.
This string is linked to a label on form 1. the string is being changed so that is not the problem I confirmed this by a adding a button which pops up a message box showing the new string value.
While searching for an answer I found that is must be some sort of refreshing problem, I tried a lot of methods with no success. Only methods that did work where those who would put my button onto form 1 instead of 2.
I've been googling for 3 hours straight on how to fix this problem but either the methods don't work or they change my button from form 2 to my main form (form 1).
Please don't call me lazy I really can't find a method that works!
EDIT:
Code
GameScreen.cs
namespace _2pGame
{
public partial class GameScreen : Form
{
public GameScreen()
{
InitializeComponent();
P1NameLabel.Text = gm.P1Name;
P1ClassLabel.Text = gm.P1Class;
P2NameLabel.Text = gm.P2Name;
P2ClassLabel.Text = gm.P2Class;
}
private void PlayerInfoButton_Click(object sender, EventArgs e)
{
PlayerInfo playerinfoload = new PlayerInfo();
playerinfoload.Show();
}
}
}
PlayerInfo.cs
namespace _2pGame
{
public partial class PlayerInfo : Form
{
public PlayerInfo()
{
InitializeComponent();
}
public void ConfirmPlayerInfo_Click(object sender, EventArgs e)
{
gm.P1Class = P1ClassChoice.Text;
gm.P1Name = P1TextBox.Text;
gm.P2Class = P2ClassChoice.Text;
gm.P2Name = P2TextBox.Text;
}
}
}
Refs.cs
namespace _2pGame
{
public partial class gm
{
public static string
P1Class,
P2Class,
P1Name,
P2Name;
}
}

An approach to this very well know situation is through delegates....
In your PlayerInfo form declare
public partial class PlayerInfo : Form
{
// define the delegate type (a parameterless method that returns nothing)
public delegate void OnConfirmPlayer();
// declare a public variable of that delegate type
public OnConfirmPlayer PlayerConfirmed;
.....
public void ConfirmPlayerInfo_Click(object sender, EventArgs e)
{
gm.P1Class = P1ClassChoice.Text;
gm.P1Name = P1TextBox.Text;
gm.P2Class = P2ClassChoice.Text;
gm.P2Name = P2TextBox.Text;
// Check is someone is interested to be informed of this change
// If someone assign a value to the public delegate variable then
// you have to call that method to let the subscriber know
if (PlayerConfirmed != null)
PlayerConfirmed();
}
}
Then in your GameScreen form, just before showing the PlayerInfo form, set the public PlayerInfo.PlayerConfirmed to a method into the GameScreen form class
private void PlayerInfoButton_Click(object sender, EventArgs e)
{
PlayerInfo playerinfoload = new PlayerInfo();
// Subscribe to the notification from PlayerInfo instance
playerinfoload.PlayerConfirmed += PlayerHasBeenConfirmed;
playerinfoload.Show();
}
// Method that receives the notification from PlayerInfo
private void PlayerHasBeenConfirmed()
{
P1NameLabel.Text = gm.P1Name;
P1ClassLabel.Text = gm.P1Class;
P2NameLabel.Text = gm.P2Name;
P2ClassLabel.Text = gm.P2Class;
}
This approach has the advantage to avoid a coupling between the GameScreen and the PlayerInfo. No need to know inside the PlayerInfo the existance of a GameScreen form and the name of its properties. You just publish a delegate that a subscriber could register to be informed of the changes and let the subscriber acts on its own code.

You need a reference to your main form and assign the textbox values each time they need to be updated.
public partial class PlayerInfo : Form
{
private readonly GameScreen _main;
public PlayerInfo(GameScreen main)
{
_main = main;
InitializeComponent();
}
public void ConfirmPlayerInfo_Click(object sender, EventArgs e)
{
gm.P1Class = P1ClassChoice.Text;
gm.P1Name = P1TextBox.Text;
gm.P2Class = P2ClassChoice.Text;
gm.P2Name = P2TextBox.Text;
main.P1NameLabel.Text = gm.P1Name;
main.P1ClassLabel.Text = gm.P1Class;
main.P2NameLabel.Text = gm.P2Name;
main.P2ClassLabel.Text = gm.P2Class;
}
}
You also need to pass the reference when the PlayerInfo form is created
private void PlayerInfoButton_Click(object sender, EventArgs e)
{
PlayerInfo playerinfoload = new PlayerInfo(this); //pass ref to self
playerinfoload.Show();
}
Note that there are other better ways to do this, but this is the easiest that I can think of.
You can probably look at events or Mediator pattern if you want something better.

Using function from popup form in existing first form

I'm having trouble figuring out how to properly do this.
The basics is that i have 1 form which is used to fill out all kinds of data which i save in 2 lists. The 2nd form is one that is called via a menu option which displays an overview of all the current data. it is opened like so:
private void OpenOverviewForm()
{
Overview formOverview = new Overview();
for (int i = 0; i < callListNL.Count; i++)
{
ListViewItem item = new ListViewItem(callListNL[i].Opco);
item.SubItems.Add(callListNL[i].UserID);
item.SubItems.Add(callListNL[i].Email);
item.SubItems.Add(callListNL[i].Title);
formOverview.listView1Overview.Items.Add(item);
}
for (int i = 0; i < callListPL.Count; i++)
{
ListViewItem item = new ListViewItem(callListPL[i].Opco);
item.SubItems.Add(callListPL[i].UserID);
item.SubItems.Add(callListPL[i].Email);
item.SubItems.Add(callListPL[i].Title);
formOverview.listView1Overview.Items.Add(item);
}
formOverview.StartPosition = FormStartPosition.CenterScreen;
formOverview.Show();
}
In this new form, there is a listview with a list of all saved logs. And what i want is for the endusers to be able to doubleclick one of the entries, which will then close the 2nd form and display the data that they've selected on the first form. In order to do that, i need to be able to use the doubleclick event of the listview to provide the index of the item that they've doubleclicked to one of my functions that exist in the first form. However i can't find a way to get my function from Form1 recognised in my Form2.
I know it's possible with the following:
public partial class Overview : Form
{
public Overview()
{
InitializeComponent();
}
private void listView1Overview_DoubleClick(object sender, EventArgs e)
{
Form1 newform = new Form1();
newform.OverviewFormDisplay(listView1Overview.SelectedIndices[0]);
}
}
But as this code actually creates a completely new instance of my original form, i don't think that this is useable. Or am i wrong?

Create a variable of your main form instance
and add constructor of Overview with reference of Form1 as parameter
public partial class Overview : Form
{
private Form1 _mainForm;
public Overview(Form1 mainform) : this()
{
this._mainForm = mainForm;
}
private void listView1Overview_DoubleClick(object sender, EventArgs e)
{
this._mainForm.OverviewFormDisplay(listView1Overview.SelectedIndices[0]);
}
}
Then you can use all public properties and methods of Form1 instance inside your Overview form
When creating instance of Overview form, pass reference of main form to constructor
//.....this line must be in the Form1
Overview formOverview = new Overview(this);
//....

You can also resolve this with creating a Property to your Overview form:
public partial class Overview : Form
{
public Overview()
{
InitializeComponent();
}
private ListViewItem lvi;
public ListViewItem SelectedItem
{
get
{
return lvi;
}
set
{
lvi = value;
}
}
private void listView1Overview_DoubleClick(object sender, EventArgs e)
{
SelectedItem = listView1Overview.SelectedItems[0];
Close();
}
}
And you have to edit your code that creates formOverview to look like this:
private void OpenOverviewForm()
{
Overview formOverview = new Overview();
for (int i = 0; i < callListNL.Count; i++)
{
ListViewItem item = new ListViewItem(callListNL[i].Opco);
item.SubItems.Add(callListNL[i].UserID);
item.SubItems.Add(callListNL[i].Email);
item.SubItems.Add(callListNL[i].Title);
formOverview.listView1Overview.Items.Add(item);
}
for (int i = 0; i < callListPL.Count; i++)
{
ListViewItem item = new ListViewItem(callListPL[i].Opco);
item.SubItems.Add(callListPL[i].UserID);
item.SubItems.Add(callListPL[i].Email);
item.SubItems.Add(callListPL[i].Title);
formOverview.listView1Overview.Items.Add(item);
}
formOverview.StartPosition = FormStartPosition.CenterScreen;
formOverview.ShowDialog();
if (formOverview.SelectedItem != null)//just in case the user closes formOverview without double-clicking any item
{
OverviewFormDisplay(formOverview.SelectedItem);
}
}
Well probably this is not the best way to do this if you don't want your formOverview to close every time the user double-clicks an item to execute those functions you wanted, but it does the work. Hopefully helps :)

c# - StackOverFlowException when mentioning ListBoxt?

I'm trying to get a new form (FormAlbum) to open when I click buttonOpenAlbum and have an item selected in the AlbumListBox.
If I just have this in buttonOpenAlbum_Click:
private void buttonOpenAlbum_Click(object sender, EventArgs e)
{
FormAlbum MusicForm = new FormAlbum(this);
MusicForm.ShowDialog();
}
The new from opens without error. However, as soon as I mention "AlbumListBox.SelectedItem" (as in the code belowin Form FormMain), I get a "StackOverflowException was unhandled" at:
public ListBox AlbumListBox
{
get
{ // <-This bracket here is where the error highlights
I don't understand why I'm getting this error, only that it must have something to do with AlbumListBox. What am I doing wrong? Any help is appreciated, thank you.
Form FormMain:
public FormMain()
{
InitializeComponent();
}
private void buttonAddAlbum_Click(object sender, EventArgs e)
{
FormAlbumAC addAlbumForm = new FormAlbumAC(this);
addAlbumForm.ShowDialog();
}
private void buttonOpenAlbum_Click(object sender, EventArgs e)
{
if (AlbumListBox.SelectedItem != null)
{
MessageBox.Show(AlbumListBox.SelectedItem.ToString());
FormAlbum MusicForm = new FormAlbum(this);
MusicForm.ShowDialog();
}
else
{
MessageBox.Show("You need to select an album from the list to open.");
}
}
public static class PublicVars
{
public static List<Album> AlbumList { get; set; }
static PublicVars()
{
AlbumList = new List<Album>(MAX_ALBUMS);
}
}
public ListBox AlbumListBox
{
get
{
return AlbumListBox;
}
}

Look at your property implementation:
public ListBox AlbumListBox
{
get
{
return AlbumListBox;
}
}
It's just calling itself, recursively. It may be easier to see that if we convert it to a method:
public ListBox GetAlbumListBox()
{
return GetAlbumListBox();
}
That's why you've got an overflow. It's not clear what you meant it to do... where did you expect the value to come from? You probably need a variable to back the property. What did you expect to set the value returned?
I'd also strongly discourage the design of the PublicVars class. Aside from the naming, you're basically using global variables - not a good idea. Work out which classes need access to the data, and how to get that data to them appropriately.

Update entire Winform

I'm a beginner at C# who's decided to create a textbased adventure game in a Winform, but I've been struggling with updating the form whenever it needs to update. In the past, I have used something.Invalidate(); to update an image, but apparently that doesn't work for an entire form.
I have a set of labels that display text based on an integer and whenever the value of the integer updates, I'd like the form to show that.
What I have tried thus far:
public partial class GameWindow : Form
{
public void buttonInventory_Click(object sender, EventArgs e)
{
Basic.HP = Basic.HP++;
this.Refresh();
}
}
While the HP updates, the form doesn't show it. Is there anything else I should use than Refresh();? A lot of googling mostly resulted in explanations about Backgroundworkers, but do I really need another thread for something as simple as this?

Why not just make a separate routine for updating values, that you call after every value change. IE: (Note - I don't program in C#):
public partial class GameWindow : Form
{
public void buttonInventory_Click(object sender, EventArgs e)
{
Basic.HP = Basic.HP++;
updateValues();
}
public void updateValues()
{
hp.text = HealthInteger;
basic.text = BasicInteger;
}
}
And call this for evey value change.

A label can't be bind to a string value like an image can be to a picture box.
The simplest solution here is too explicitly set the Text property of the label each time your HP property is changed :
private void RefreshFormWithModel(Basic basic)
{
labelHP.Text = basic.HP;
}
public void buttonInventory_Click(object sender, EventArgs e)
{
Basic.HP = Basic.HP++;
this.RefreshFormWithModel(Basic);
}
If you really want complex binding, here is some lectures.

I'm going to assume the class name of Basic is just Basic
in the class Basic
private int hp;
public int HP
{
get { return hp; }
set { hp = value; HP_Changed(); }
}
public event EventHandler HPChanged;
private void HP_Changed()
{
if (HPChanged != null) { HPChanged(this, new EventArgs()); }
}
in the GameWindow
//where ever you create a new Basic, add to the event handler
Basic Basic = new Basic();
Basic.HPChanged += Basic_HPChanged;
private void Basic_HPChanged(object sender, EventArgs e)
{
Basic b_sender = (Basic)sender;
int NewHealth = b_sender.HP;
//Update whatever value needs to be updated, here
}
Then whenever the HP of the Basic is changed, it will fire an event in the GameWindow to update the appropriate field.