Develop Reference

Access properties of a Windows Form which was created in another Windows Form [duplicate]

How do I get access to the parent controls of user control in C# (winform). I am using the following code but it is not applicable on all types controls such as ListBox.
Control[] Co = this.TopLevelControl.Controls.Find("label7", true);
Co[0].Text = "HelloText"
Actually, I have to add items in Listbox placed on parent 'Form' from a user control.

Description
You can get the parent control using Control.Parent.
Sample
So if you have a Control placed on a form this.Parent would be your Form.
Within your Control you can do
Form parentForm = (this.Parent as Form);
More Information
MSDN: Control.Parent Property
Update after a comment by Farid-ur-Rahman (He was asking the question)
My Control and a listbox (listBox1) both are place on a Form (Form1). I have to add item in a listBox1 when user press a button placed in my Control.
You have two possible ways to get this done.
1. Use `Control.Parent
Sample
MyUserControl
private void button1_Click(object sender, EventArgs e)
{
if (this.Parent == null || this.Parent.GetType() != typeof(MyForm))
return;
ListBox listBox = (this.Parent as MyForm).Controls["listBox1"] as ListBox;
listBox.Items.Add("Test");
}
or
2.
put a property public MyForm ParentForm { get; set; } to your UserControl
set the property in your Form
assuming your ListBox is named listBox1 otherwise change the name
Sample
MyForm
public partial class MyForm : Form
{
public MyForm()
{
InitializeComponent();
this.myUserControl1.ParentForm = this;
}
}
MyUserControl
public partial class MyUserControl : UserControl
{
public MyForm ParentForm { get; set; }
public MyUserControl()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (ParentForm == null)
return;
ListBox listBox = (ParentForm.Controls["listBox1"] as ListBox);
listBox.Items.Add("Test");
}
}

You can use Control.Parent to get the parent of the control or Control.FindForm to get the first parent Form the control is on. There is a difference between the two in terms of finding forms, so one may be more suitable to use than the other.:
The control's Parent property value might not be the same as the Form
returned by FindForm method. For example, if a RadioButton control is
contained within a GroupBox control, and the GroupBox is on a Form,
the RadioButton control's Parent is the GroupBox and the GroupBox
control's Parent is the Form.

Control has a property called Parent, which will give the parent control. http://msdn.microsoft.com/en-us/library/system.windows.forms.control.parent.aspx
eg Control p = this.Parent;

You can get the Parent of a control via
myControl.Parent
See MSDN:
Control.Parent

A generic way to get a parent of a control that I have used is:
public static T GetParentOfType<T>(this Control control)
{
const int loopLimit = 100; // could have outside method
var current = control;
var i = 0;
do
{
current = current.Parent;
if (current == null) throw new Exception("Could not find parent of specified type");
if (i++ > loopLimit) throw new Exception("Exceeded loop limit");
} while (current.GetType() != typeof(T));
return (T)Convert.ChangeType(current, typeof(T));
}
It needs a bit of work (e.g. returning null if not found or error) ... but hopefully could help someone.
Usage:
var parent = currentControl.GetParentOfType<TypeWanted>();
Enjoy!

According to Ruskins answer and the comments here I came up with the following (recursive) solution:
public static T GetParentOfType<T>(this Control control) where T : class
{
if (control?.Parent == null)
return null;
if (control.Parent is T parent)
return parent;
return GetParentOfType<T>(control.Parent);
}

Not Ideal, but try this...
Change the usercontrol to Component class (In the code editor), build the solution and remove all the code with errors (Related to usercontrols but not available in components so the debugger complains about it)
Change the usercontrol back to usercontrol class...
Now it recognises the name and parent property but shows the component as non-visual as it is no longer designable.

((frmMain)this.Owner).MyListControl.Items.Add("abc");
Make sure to provide access level you want at Modifiers properties other than Private for MyListControl at frmMain

If you want to get any parent by any child control you can use this code,
and when you find the UserControl/Form/Panel or others you can call funnctions or set/get values:
Control myControl= this;
while (myControl.Parent != null)
{
if (myControl.Parent!=null)
{
myControl = myControl.Parent;
if (myControl.Name== "MyCustomUserControl")
{
((MyCustomUserControl)myControl).lblTitle.Text = "FOUND IT";
}
}
}

How to prevent cursor from getting stuck in winform control due to validation [duplicate]

Does anyone know if there is a way to get a list of controls that have the ErrorProvider icon active. ie. any controls that failed validation. I'm trying to avoid looping all controls in the form.
I'd like to display some sort of message indicating how many errors there are on the form. As my form contains tabs I'm trying to make it apparent to the user that errors may exist on inactive tabs and they need to check all tabs.
Thanks
Barry

This falls in the category of "how can you not know". It is your code that is calling ErrorProvider.SetError(), you should have no trouble keeping track of how many errors are still active. Here's a little helper class, use its SetError() method to update the ErrorProvider. Its Count property returns the number of active errors:
private class ErrorTracker {
private HashSet<Control> mErrors = new HashSet<Control>();
private ErrorProvider mProvider;
public ErrorTracker(ErrorProvider provider) {
mProvider = provider;
}
public void SetError(Control ctl, string text) {
if (string.IsNullOrEmpty(text)) mErrors.Remove(ctl);
else if (!mErrors.Contains(ctl)) mErrors.Add(ctl);
mProvider.SetError(ctl, text);
}
public int Count { get { return mErrors.Count; } }
}

Today I had the same problem. My solution is to extend the ErrorProvider control.
See the code below:
public class MyErrorProvider : ErrorProvider
{
public List<Control> GetControls()
{
return this.GetControls(this.ContainerControl);
}
public List<Control> GetControls(Control ParentControl)
{
List<Control> ret = new List<Control>();
if (!string.IsNullOrEmpty(this.GetError(ParentControl)))
ret.Add(ParentControl);
foreach (Control c in ParentControl.Controls)
{
List<Control> child = GetControls(c);
if (child.Count > 0)
ret.AddRange(child);
}
return ret;
}
}
You can use the above derived class in your form, and then (say that myErrorProvider is the class instance in your form) you can get all the controls with errors in your form, by calling:
List<Control> errorControls = myErrorProvider.GetControls();

This is a moderately tricky solution you are talking about.
There is no way to achieve this automatically, as far as I know.
You have to maintain a flag for every control and manually set it every time an error-provider is blinked.
May be a Dictionary<TKey, TValue> can be used to keep track of it.

You have to use SetError to set the error on the control in the first place, right? Perhaps you should store that information in another collection at the same time if you want to have it handy. For example, you could add each control with an error to a hashset.

Just make the errorprovider as a Global variable rather than local variable
public partial class MainForm
{
ErrorProvider errorProvider1 = new ErrorProvider();
void Validate_Working()
{
errorProvider1.SetError(textbox1, "textbox is empty");
errorProvider1.Clear();
}
}
from
public partial class MainForm
{
Void Validate_NotWorking()
{
ErrorProvider errorProvider1 = new ErrorProvider();
errorProvider1.SetError(textbox1, "textbox is empty");
errorProvider1.Clear();
}
}
This should fix your problem, because probably you might have been removing your errors from another method such as btnCancel_click.
This worked for me :)

Passing value between forms [duplicate]

How do I pass a value from a child back to the parent form? I have a string that I would like to pass back to the parent.
I launched the child using:
FormOptions formOptions = new FormOptions();
formOptions.ShowDialog();

Create a property (or method) on FormOptions, say GetMyResult:
using (FormOptions formOptions = new FormOptions())
{
formOptions.ShowDialog();
string result = formOptions.GetMyResult;
// do what ever with result...
}

If you're just using formOptions to pick a single value and then close, Mitch's suggestion is a good way to go. My example here would be used if you needed the child to communicate back to the parent while remaining open.
In your parent form, add a public method that the child form will call, such as
public void NotifyMe(string s)
{
// Do whatever you need to do with the string
}
Next, when you need to launch the child window from the parent, use this code:
using (FormOptions formOptions = new FormOptions())
{
// passing this in ShowDialog will set the .Owner
// property of the child form
formOptions.ShowDialog(this);
}
In the child form, use this code to pass a value back to the parent:
ParentForm parent = (ParentForm)this.Owner;
parent.NotifyMe("whatever");
The code in this example would be better used for something like a toolbox window which is intended to float above the main form. In this case, you would open the child form (with .TopMost = true) using .Show() instead of .ShowDialog().
A design like this means that the child form is tightly coupled to the parent form (since the child has to cast its owner as a ParentForm in order to call its NotifyMe method). However, this is not automatically a bad thing.

You can also create a public property.
// Using and namespace...
public partial class FormOptions : Form
{
private string _MyString; // Use this
public string MyString { // in
get { return _MyString; } // .NET
} // 2.0
public string MyString { get; } // In .NET 3.0 or newer
// The rest of the form code
}
Then you can get it with:
FormOptions formOptions = new FormOptions();
formOptions.ShowDialog();
string myString = formOptions.MyString;

You can also create an overload of ShowDialog in your child class that gets an out parameter that returns you the result.
public partial class FormOptions : Form
{
public DialogResult ShowDialog(out string result)
{
DialogResult dialogResult = base.ShowDialog();
result = m_Result;
return dialogResult;
}
}

Use public property of child form
frmOptions {
public string Result; }
frmMain {
frmOptions.ShowDialog(); string r = frmOptions.Result; }
Use events
frmMain {
frmOptions.OnResult += new ResultEventHandler(frmMain.frmOptions_Resukt);
frmOptions.ShowDialog(); }
Use public property of main form
frmOptions {
public frmMain MainForm; MainForm.Result = "result"; }
frmMain {
public string Result;
frmOptions.MainForm = this;
frmOptions.ShowDialog();
string r = this.Result; }
Use object Control.Tag; This is common for all controls public property which can contains a System.Object. You can hold there string or MyClass or MainForm - anything!
frmOptions {
this.Tag = "result": }
frmMain {
frmOptions.ShowDialog();
string r = frmOptions.Tag as string; }

Well I have just come across the same problem here - maybe a bit different. However, I think this is how I solved it:
in my parent form I declared the child form without instance e.g. RefDateSelect myDateFrm; So this is available to my other methods within this class/ form
next, a method displays the child by new instance:
myDateFrm = new RefDateSelect();
myDateFrm.MdiParent = this;
myDateFrm.Show();
myDateFrm.Focus();
my third method (which wants the results from child) can come at any time & simply get results:
PDateEnd = myDateFrm.JustGetDateEnd();
pDateStart = myDateFrm.JustGetDateStart();`
Note: the child methods JustGetDateStart() are public within CHILD as:
public DateTime JustGetDateStart()
{
return DateTime.Parse(this.dtpStart.EditValue.ToString());
}
I hope this helps.

For Picrofo EDY
It depends, if you use the ShowDialog() as a way of showing your form and to close it you use the close button instead of this.Close(). The form will not be disposed or destroyed, it will only be hidden and changes can be made after is gone. In order to properly close it you will need the Dispose() or Close() method. In the other hand, if you use the Show() method and you close it, the form will be disposed and can not be modified after.

If you are displaying child form as a modal dialog box, you can set DialogResult property of child form with a value from the DialogResult enumeration which in turn hides the modal dialog box, and returns control to the calling form. At this time parent can access child form's data to get the info that it need.
For more info check this link:
http://msdn.microsoft.com/en-us/library/system.windows.forms.form.dialogresult(v=vs.110).aspx

i had same problem i solved it like that , here are newbies step by step instruction
first create object of child form it top of your form class , then use that object for every operation of child form like showing child form and reading value from it.
example
namespace ParentChild
{
// Parent Form Class
public partial class ParentForm : Form
{
// Forms Objects
ChildForm child_obj = new ChildForm();
// Show Child Forrm
private void ShowChildForm_Click(object sender, EventArgs e)
{
child_obj.ShowDialog();
}
// Read Data from Child Form
private void ReadChildFormData_Click(object sender, EventArgs e)
{
int ChildData = child_obj.child_value; // it will have 12345
}
} // parent form class end point
// Child Form Class
public partial class ChildForm : Form
{
public int child_value = 0; // variable where we will store value to be read by parent form
// save something into child_value variable and close child form
private void SaveData_Click(object sender, EventArgs e)
{
child_value = 12345; // save 12345 value to variable
this.Close(); // close child form
}
} // child form class end point
} // name space end point

Many ways to skin the cat here and #Mitch's suggestion is a good way. If you want the client form to have more 'control', you may want to pass the instance of the parent to the child when created and then you can call any public parent method on the child.

I think the easiest way is to use the Tag property
in your FormOptions class set the Tag = value you need to pass
and after the ShowDialog method read it as
myvalue x=(myvalue)formoptions.Tag;

When you use the ShowDialog() or Show() method, and then close the form, the form object does not get completely destroyed (closing != destruction). It will remain alive, only it's in a "closed" state, and you can still do things to it.

The fastest and more flexible way to do that is passing the parent to the children from the constructor as below:
Declare a property in the parent form:
public string MyProperty {get; set;}
Declare a property from the parent in child form:
private ParentForm ParentProperty {get; set;}
Write the child's constructor like this:
public ChildForm(ParentForm parent){
ParentProperty= parent;
}
Change the value of the parent property everywhere in the child form:
ParentProperty.MyProperty = "New value";
It's done. the property MyProperty in the parent form is changed. With this solution, you can change multiple properties from the child form. So delicious, no?!

Retrieve all winforms components in all subclasses

I would like to retrieve all components which are part of a Form's or UserControl's components collection.
The components collection is added by VS winforms designer. The components variable is private and the problem is how to retrieve all components from all descendants. I would like to have a method which returns list of components throught the type hierarchy. For example let's say I have MyForm (descendant of BaseForm) and BaseForm (descendant of Form). I would like to put method "GetComponents" which returns components of both MyForm and BaseForm.
Do you suggest any other option than using the reflection?

Some time ago I have implemented the solution in which I created custom base form and control implementations, adding one property and overriding the OnLoad method:
public partial class FormBase : Form
{
public FormBase ()
{
this.InitializeComponent();
}
protected ConsistencyManager ConsistencyManager { get; private set; }
protected override void OnLoad(System.EventArgs e)
{
base.OnLoad(e);
if (this.ConsistencyManager == null)
{
this.ConsistencyManager = new ConsistencyManager(this);
this.ConsistencyManager.MakeConsistent();
}
}
}
The ConsistencyManager class finds all controls, components and also supports search of custom child controls within specific control. Copy/paste of code from MakeConsistent method:
public void MakeConsistent()
{
if (this.components == null)
{
List<IComponent> additionalComponents = new List<IComponent>();
// get all controls, including the current one
this.components =
this.GetAllControls(this.parentControl)
.Concat(GetAllComponents(this.parentControl))
.Concat(new Control[] { this.parentControl });
// now find additional components, which are not present neither in Controls collection nor in components
foreach (var component in this.components)
{
IAdditionalComponentsProvider provider = GetAdditinalComponentsProvider(component.GetType().FullName);
if (provider != null)
{
additionalComponents.AddRange(provider.GetChildComponents(component));
}
}
if (additionalComponents.Count > 0)
{
this.components = this.components.Concat(additionalComponents);
}
}
this.MakeConsistent(this.components);
}
If anyone would like full sample or source let me know.
Best regards,
Zvonko
PS: In the same manner I have also created the performance counter that counts number of invocations on main thread.

Custom control derived from Component - OnCreate event?

I've created simple custom control - derived from Component class:
public partial class TrialChecker : Component
{
private int _trialDays;
public int TrialDays
{
get { return _trialDays; }
set { _trialDays = value;}
}
public TrialChecker()
{
InitializeComponent();
MessageBox.Show(TrialDays.ToString());
}
public int GetTrialDays()
{
return _trialDays;
}
}
This control will be used to implement trial functionality in my application. Application (before it starts) should check trial remaining days and display notify dialog containing trial remaining days and textbox to write unlock key.
But I want to minimalise amount of code needed to wirte while using this control. So, my idea is to place trial check code inside my control and - just after control is created, it should display remaining days.
Trial period (TrialDays property) is set on user designer and it should be available to use just afeter control is created. As you can see, I tried to put this to constructor but it does not work, because constructor is called before setting TrialDays to valuje entered in user designer. And MessageBox always displays default value 0.
There is no any OnLoad or OnCreate events abailable to override. So, how can I automatically check trial status using value entered in designer?

The Component class is very simple, it just provides a way to host the component on a form at design time, giving access to its properties with the Properties window. But it has no notable useful events, using a component requires explicit code in the form. Like OpenFormDialog, nothing happens with it until you call its ShowDialog() method.
The constructor is usable but unfortunately it runs too early. The DesignMode property tells you whether or not a component runs at design time but it isn't set yet at constructor time. You'll need to delay the code and that's difficult because there are no other methods or events that run later.
A solution is to use the events of the form that you dropped the component on. Like the Load event. That requires some giddy code to coax the designer to tell you about the form. That technique is used by the ErrorProvider component, it requires exposing a property of type ContainerControl and overriding the Site property setter. Like this:
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms;
public partial class Component1 : Component {
private ContainerControl parent;
[Browsable(false)]
public ContainerControl ContainerControl {
get { return parent; }
set {
if (parent == null) {
var form = value.FindForm();
if (form != null) form.Load += new EventHandler(form_Load);
}
parent = value;
}
}
public override ISite Site {
set {
// Runs at design time, ensures designer initializes ContainerControl
base.Site = value;
if (value == null) return;
IDesignerHost service = value.GetService(typeof(IDesignerHost)) as IDesignerHost;
if (service == null) return;
IComponent rootComponent = service.RootComponent;
this.ContainerControl = rootComponent as ContainerControl;
}
}
void form_Load(object sender, EventArgs e) {
if (!this.DesignMode) {
MessageBox.Show("Trial");
}
}
}
The code is inscrutable, but you can be pretty sure it is reliable and stable because this is what the ErrorProvider component uses. Be sure to call Environment.Exit() when the trial period has ended, an exception isn't going to work well.