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Pass Parameters Between Windows
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Closed 7 years ago.
My problem is, to pass some information from a WPF window to an existing WPF page. I would like to open a the window by pressing a button on WPF Page1.
Then, i have to get all the text stored in Textbox1 to a variable in Page1. But only when the user presses ButtonXY on the "Window". How can i solve this Problem without using the "Bindings" because there has to be abig "Switch" clause next to Page1?
If you are using MVVM then both the window and the page could have a common ViewModel and those TextBoxes should be bound to the same property with UpdateSourceTrigger set to PropertyChanged and this way no more events or notifications are needed.
Otherwise, sometimes i tend to create a global project which will be added as a references where needed. This way, you will be able to set events and their handlers to accomplish your specific issues. I think this is not an elegant solution but it helps me a lot communicating between different projects or classes.
Make a new class that will contain all your data you want to transfer between all your windows.
public YourNewClassWithSettings
{
string StringNumber1;
string StringNumber2;
}
Create an instance of this class in your main window and set the values of the properties you want.
Pass the instance of YourNewClassWithSettings by reference to your constructor of your next window.
YourNewClassWithSettings test = new YourNewClassWithSettings();
test.StringNumber1 = "mySetting";
WindowControl w = new WindowControl(ref test);
w.ShowDialog();
//See what was changed!!!!
string changedValue = test.StringNumber1; //Will be "IamDone"
In your constructor you would say:
public WindowControl(ref YourNewClassWithSettings test)
{
// example: You can now say TextBox1.Text = test.StringNumber1;
// Whatever you change here like test.
test.StringNumber1 = "IamDone";
//When you close this window, because test was passed by ref : you
// will see StringNumber1 = "IamDone" in your main window again
//when accessing the property of that class. Always pass by ref
this.Close();
}
This is the MVVM approach.
Lets assume you have a MainWindow and a SubWindow.
Your SubWindow contains a Button and a Textbox. When you click on the Button in the SubWindow you want to transfer the Text from the Textbox into the MainWindow.
Main Window.
You implment a Property (a Getter and Setter) wich will contain the transfered Text string. The MainWindow contains also the SubWindow! Don't forget to pass the MainWindow into the SubWindow Constructor (look below) so the SubWindow know the MainWindow instance
public partial class MainWindow : Window
{
public string Text { get; set; }
private Window subWindow;
public MainWindow()
{
InitializeComponent();
subWindow = new SubWindow(this);
subWindow.Show();
}
}
SubWindow
public partial class SubWindow : Window
{
private Window mainWindow;
public SubWindow(Window mainWindow)
{
this.mainWindow = mainWindow;
InitializeComponent();
}
private void ButtonTransferTheData_Click(object sender, RoutedEventArgs e)
{
mainWindow.Text = myTextBoxInSubWindow.Text;
}
}
Your SubWindow knows the MainWindow. So you can access the Text Property. On the Button click you wirte the Text from the Textbox into the Property of the MainWindow.
HINT
The mainWindow.Text = myTextBoxInSubWindow.Text; line could throw an exception. this is because you want to access a thread from another.
So you need to dispatch it. Change this line into:
Dispatcher.Invoke(() => mainWindow.Text = myTextBoxInSubWindow.Text);
Hope this helps.
Related
I have a form populated with an array of userControls that is created from the main form. I need to be able to access this array of userControls from the main form once the popup has been closed when a button is pressed. If I fill out the forms and then press the button on the main form without closing the popup, the values are present. However, if I close the popup window, the values are not present. My main form is static so I can use it's variables in other forms.
Code for the popup:
public ScanChannel[] controls;
public ScanListSetup()
{
InitializeComponent();
int numChans = Convert.ToInt32(Form1.Self.numChannels.Text);
controls = new ScanChannel[numChans];
// Create the UserControls
for(int i = 0; i < numChans; i++)
{
controls[i] = new ScanChannel();
}
// Place them
for (int i = 0; i < numChans; i++)
{
controls[i].Location = new Point(13,(35+25*(i)));
this.Controls.Add(controls[i]);
}
doneButton.Location = new Point(82, 35 + (25 * (numChans + 1)));
this.Size =new Size(280, 110 + (25 * (numChans + 1)));
}
private void doneButton_Click(object sender, EventArgs e)
{
Form1.Self.setChannelsToScan(controls);
}
I need to access the controls array in the main form. The code for the main form is as follows:
private ScanChannel[] channelsToScan;
private void configureScanListButton_Click(object sender, EventArgs e)
{
var form = new ScanListSetup();
form.Show(this);
scanListConfigured = true;
this.channelsToScan = new ScanChannel[Convert.ToInt32(numChannels.Text)];
}
public void setChannelsToScan(ScanChannel[] arr)
{
for (int i = 0; i < arr.Length; i++)
{
this.channelsToScan[i] = arr[i];
}
}
private void scanButton_Click(object sender, EventArgs e)
{
System.Diagnostics.Debug.WriteLine("Test: " + this.channelsToScan[0].getDeviceType());
// THIS PRINTS AN EMPTY STRING
}
So, the Debug writeLine outputs the correct value if I click the scanButton while the popup form is still open. However, if I close the form after clicking the doneButton on the popup form, the Debug writeLine outputs Test: with nothing else.
Any help with this would be greatly appreciated. Thanks.
Your problem essentially boils down to sending data from a secondary window (your 'pop-up' window) to the main window from where it was created. It doesn't matter whether you're working with Windows Control objects or simple data types like string, so I'm going to use a simple example to illustrate how to handle such a situation.
Let's assume you have a Main form that looks like this. It has an OPEN button and a TextBox.
When you click OPEN, it opens up this secondary input window (your pop-up) which looks like this:
Now the idea is this. You click OPEN and opens the Input form, and lets the user enter some text into the TextBox there. Once you click the OK button, it should close the Input window, and display the text entered by the user in the Main window. Remember that at this point the Input window is closed, which is equivalent to your situation.
So I'd make use of Delegates to accomplish this goal. A delegate lets you transfer data between windows which is what you want.
In my Main I'd declare a public delegate with a signature like this:
public delegate void DataTransfer(string data);
That is, this delegate represents a method that takes in a single string parameter, and has void return type. The idea is to let the secondary Input window 'call' a method in the Main, and that method takes in a string parameter. So, if there was a way for us to call a method that resides in the Main from Input, and pass a string, we can then take the user input text in the Input window, and pass it to the Main window. With me so far?
Now, if I write a method like this in the Main, and let it be called from Input, that should accomplish our goal. Here, txtDisplay is the TextBox in the Main form.
public void ReceiveInput(string data)
{
txtDisplay.Text = data;
}
To accomplish this, I would define a delegate of type DataTransfer in the Main form like below, and register the ReceiveInput() method to it. Your Main form code behind should look like this:
public delegate void DataTransfer(string data);
public partial class MainForm : Form
{
public DataTransfer transferDelegate;
InputForm inputForm = null;
public MainForm()
{
InitializeComponent();
transferDelegate += new DataTransfer(ReceiveInput);
}
public void ReceiveInput(string data)
{
txtDisplay.Text = data;
}
private void BtnOpen_Click(object sender, EventArgs e)
{
inputForm = new InputForm(transferDelegate);
inputForm.Show();
}
}
BtnOpen is the OPEN button in the Main form, and when it's clicked, it passes the delegate to the Input form, then opens it. So, accordingly, we need to now modify our Input form:
public partial class InputForm : Form
{
DataTransfer transferDel;
public InputForm(DataTransfer del)
{
InitializeComponent();
transferDel = del;
}
private void BtnOK_Click(object sender, EventArgs e)
{
string data = txtInput.Text;
transferDel.Invoke(data);
Close();
}
}
Here, we modify the constructor so that it takes in a delegate of type DataTransfer, and sets it to the local instance of the same type. Then, at the click of BtnOK on the Input form, we take in the text input by user, and pass that text to the said delegate and invoke it. 'Invoking' is the same as calling the method in the Main form. At this point, you can Clsoe() the Input window as shown above, and you'd still have access to the user input string data from your Main form.
You can use this same approach, and instead of strings you can pass around Controls. However, it's not the best approach to pass around a bunch of controls back and forth, so ideally you would extract the data you need from those controls in your pop-up, and pass only the said data instead of the whole controls.
EDIT: After OP posted the erroneous code.
OK, so here's your issue. The testUserControl class is not a regular class but a control element derived from UserControl. In otherwise, a GUI element. You shouldn't use GUI elements to pass data around. Because, when you do your controlArr[i].getText();, it tries to get the text from the textItem, but textItem is a TextBox Control which doesn't exist at this point because you closed your window. Remember, you do the delegate.Invoke() only once, and at that point *you must send ALL the data back to your main window*.
What you should do is, simply define a class to hold ALL the data you want to pass to your main. For example something like this:
public class DataToPass
{
public string TextBoxText { get; set; }
public string SomeOtherData { get; set; }
// Other stuff you want...
}
Now, instead of passing an array of testUserControl, pass an array of DataToPass. That way, at the Main form you don't have to do the following:
controlArr[i].getText();
Instead you'd simply do something like:
controlArr[i].TextBoxText;
where controlArr now is an array of type DataToPass.
Simply, passing a control derived from UserControl is not a good idea. Just create one class that is capable of holding ALL the data you want to pass and pass it back to the main once.
I'm trying to pass a variable from one form to another form textbox. The 'variable' is a result of a calculation based on the user inputs.
Below is the code for the parent form(RuleInsertForm) where I'm calling the subform(Helpformula) to get the user inputs.
public partial class RuleInsertForm : Form
{
public string helpformulainputs;
}
private void RuleInsertForm_Load(object sender,EventArgs e)
{
if (helpformulainputs=="")
{
textBox_Inputs.Text = "";
}
else
{
textBox_Inputs.Text = helpformulainputs;
}
}
Below is the code for the subform(Helpformula) where i'm passing the result variable(formulainputs) to the parent form(RuleInsertForm).
public partial class HelpFormula : Form
{
public string formulainputs = string.Empty;
private void button_generateformula_Click(objectsender, EventArgs e)
{
using (RuleInsertForm insertform = new RuleInsertForm())
{
insertform.helpformulainputs = formulainputs;
this.Close();
insertform.Show();
}
}
}
Problem:
The values are getting passed to the text box but in the UI its not getting dispalyed.
so far I tried to push data back to parent form and then tried to display the data in the textbox where I failed.(I dont know where it went wrong suggest me if I can resolve the below one)
Now I need an alternative method to this for eg: instead of pushing the data back to parent form i need to make the variable available for all the forms trying to use the subform(formulainputs)
How can I acheive this process ? any suggestions are much appreciated.
The problem seems to be that insertForm.Show() does not block the execution of your button handler. Show opens the insertform as non-modal.
So after insertform is opened, the execution is continued in button_generateformula_Click and when you exit the using block, the insertform is disposed and therefore closed.
To solve this you may call insertForm.ShowDialog() instead.
For different ways of communicating between Forms look here or simply type communicate between forms into the SO search box.
I seem to be have a great deal of trouble with a simple issue. Yes I'm new to c# but I try to learn what I can without jumping to post a question. In this case I just think I'm not asking the right question.
No code samples will help here because I'm talking about the basics ( implementation ). I have not really coded anything yet, just use the visual builder to create my windows forms and menus.
The issue I'm having is when I select a menu item (call it: set paths ) I want that list view on my main form to load from the path selected when I hit ok on form2. So I did a simple find folder dialog and I have my new path stored on form2 in a text box. When I hit ok on that form2 I want my listview form1 to populate. I know how to do all of this but I can not for the life of me access form1 from form2 or vice versa.
I tried making a call back function but I get that non-static variable cannot be referenced... error because my form1 is static, so I can't create any non static methods. I looked in to EventArgs but that just seems like an over kill for such a common request.
So what is the general way to do this?
Robert's answer is correct as far as accessing members on another form. However, in general you should be storing the state of your application (call it the "model") separately from the state of your user interface (call it the "view"). This becomes very important as your application grows beyond one or two interactions. There are several philosophies or patterns about how to tie the two together (Google "model-view-controller" (MVC) and "model-view-viewmodel" (MVVM) for example), and if you really want to do this correctly I would recommend learning about those. My preference is for the MVVM approach, and you can do it fairly easily with Windows Forms even though it was designed with WPF applications in mind.
In .NET, the basic piece of code you should use to implement the connection between your viewmodel and your view is an interface called INotifyPropertyChanged. You create a class that implements this interface and sends notifications whenever a property changes, so for example for your path property you would create this class:
class ViewModel : INotifyPropertyChanged
{
private string path;
public string Path
{
get { return path; }
set {
if (value != path)
{
path = value;
NotifyPropertyChanged();
}
}
}
// This event gets triggered whenever a property changes.
public event PropertyChangedEventHandler PropertyChanged;
// This will cause the event to actually be triggered. It automatically determines the name of the property that triggered it using the [CallerMemberName] attribute - just a bit of .NET 4.5 sweetness. :)
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
It may seem like a lot of work, but now in your form1 you can create a new "ViewModel" instance, subscribe to the event, and then pass the instance to form2. form2 then simply updates the Path property on the viewmodel instance whenever the user selects a different path.
So, Form1 needs this code near the top:
private ViewModel viewmodel = new ViewModel();
And this goes in the Form1 constructor:
viewmodel.PropertyChanged += new EventHandler(OnPathChanged);
And when you create/show form2:
var form2 = new Form2(viewmodel); // Note, the viewmodel instance is being passed to the form2 constructor
form2.Show();
The form2 constructor then stores its own reference to the "viewmodel" instance, and sets the Path property whenever the path is changed by the user.
private ViewModel viewmodel;
public Form2(ViewModel viewmodel)
{
this.viewmodel = viewmodel;
... // Other stuff to set up your controls etc. goes here
}
private void PathChanged(object sender, EventArgs e) // This may be named differently in your code; it's the event handler that gets called when the path changes
{
// This will automatically notify the event handler in Form1! It's super-elegant and flexible.
this.viewmodel.Path = txtPath.Text; // Assuming you have a textbox called txtPath
}
And finally the event handler in Form1:
private void OnPathChanged(object sender, EventArgs e)
{
var newPath = viewmodel.Path; // Get the updated path back from the viewmodel
//TODO: Whatever you want to do when the path changes.
}
Here's a link to a really good MVVM intro using Windows Forms, it uses two forms like you have in your example. MVVM (Model-View-ViewModel) Pattern For Windows Form Applications, using C#
If you need to access something on another form, just hold a reference to it from your first form, like this:
form2 = new Form2();
form2.Show();
form2.WhateverYouWantToAccess
That said, if you just want to get a file path from the user, you want to use the OpenFileDialog class.
private void button1_Click(object sender, System.EventArgs e)
{
Stream myStream = null;
OpenFileDialog openFileDialog1 = new OpenFileDialog();
openFileDialog1.InitialDirectory = "c:\\" ;
openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*" ;
openFileDialog1.FilterIndex = 2 ;
openFileDialog1.RestoreDirectory = true ;
if(openFileDialog1.ShowDialog() == DialogResult.OK)
{
try
{
if ((myStream = openFileDialog1.OpenFile()) != null)
{
using (myStream)
{
// Insert code to read the stream here.
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
}
}
}
Basically, I have a settings window, and when you click "OK", it's suppose to apply settings to the main form (eg, set font of a control, etc), and then close.
frmmain frm = new frmmain();
frm.OLVAltBackColor = Color.Aquamarine ;
I tried that, but it only applies the settings to that instance, and you can see it if you do frm.Show();
I'm trying to make it so the already opened form has it's control's properties changed.
What you are trying to do is not working because you are creating a NEW instance of your main form and updating that rather than the first instance. It is possible to update the main form by keeping a reference to it in your settings form... but...
...it sounds like you are approaching this from the wrong direction.
Don't make the settings form dependent on the main form. Instead create the settings form from the main dialog.
class SettingsForm : Form
{
// You need to ensure that this color is updated before the form exits
// either make it return the value straight from a control or set it
// as the control is updated
public Color OLVAltBackColor
{
get;
private set;
}
}
In your main form
(I'm assuming some kind of button or menu click)
private void ShowSettingsClicked(object sender, EventArgs args)
{
using (SettingsForm settings = new SettingsForm())
{
// Using 'this' in the ShowDialog parents the settings dialog to the main form
if (settings.ShowDialog(this) == DialogResult.OK)
{
// update settings in the main form
this.OLVAltBackColor = settings.OLVAltBackColor;
}
}
}
Apply the property change to the form that already exists and is already shown instead of creating a new form and changing that one.
In this code you're creating a new instance of the frmmain. Any changes you make to that new object will happen in the new object, not the one you actually want to change.:
frmmain frm = new frmmain(); //Creating a new object isn't the way.
frm.OLVAltBackColor = Color.Aquamarine ;
What you're looking for is a way to call on the already existant frmmain class and change the property of that.
Edit, for example:
using System;
class Statmethod
{
//A class method declared
static void show()
{
int x = 100;
int y = 200;
Console.WriteLine(x);
Console.WriteLine(y);
}
public static void Main()
{
// Class method called without creating an object of the class
Statmethod.show();
}
}
I'm new to C# and would like to allow to Windows forms to comminicate with each other. I googled bubbling in C# but it wasn't much help. What are some good ways I can learn bubbling?
EDIT: I want to have an options form that is shown/created when my user clicks on Edit->Preferances. I then want the settings the user changed in the options form to be relayed to the main form.
Two approaches:
Put properties on your preferences form and access them from the main form when the user clicks OK.
if (preferenceForm.ShowDialog() == DialogResult.OK)
{
this.Color = preferenceForm.UserSelectedColor;
//etc...
}
Send your preference form a delegate from the main form and let the preference form call it with the appropriate changes.
class FormSettings
{
object Color {get, set}
}
class MainForm
{
...
void ChangeSettings(FormSettings newSettings)
{ ... }
void EditPreferences_Click(...)
{
...
EditPreferencesForm editPreferences = new EditPreferencesForm(this.ChangeSettings)
editPreferences.ShowDialog();
}
}
class EditPreferencesForm
{
...
ChangeSettingsDelegate changeSettings;
FormSettings formSettings;
void OkButton_Click(...)
{
changeSettings(formSettings);
}
}
You don't state as much, but is the main form also the form that contains the Edit->Preferences menu? If so, you are already at the correct point in the code
// This is the event handler in the main form
private void mnuEditPreferencesClicked...
{
FrmPreferences frmPreferences = new FrmPreferences();
frmPreferences.ShowDialog(this);
// Preferences saved, implement changes to main form here
}
If the preferences form is not generated from the main form, fire off an event when the preferences form closes, and have the main form handle the event that way.