Removing a TextBox from the Controls collection has no effect - c#

Basically what I do is: Add (n) textboxes via a button click. When I again click on it, this code runs:
foreach (Control c in this.Controls)
{
TextBox tb = c as TextBox;
if (tb != null)
{
this.Controls.Remove(tb);
tb.Dispose();
}
}
I than again add (n) textboxes, but every second item from the old textboxes remains. Any ideas?

Removing items from the collection you are iterating on is a bad idea. Try this:
List<Control> toBeRemoved = new List<Control>();
foreach (Control c in this.Controls)
{
if (c instanceof TextBox)
{
toBeRemoved.Add(c);
}
}
foreach (Control c in toBeRemoved)
{
this.Controls.Remove(c);
c.Dispose();
}

Related

Find a ListView control in tab page

I have 2 listviews in tab page. however I am looking for a function to find the right control by name:
I have
foreach (Control c in form.Controls) // loop through form controls
{
if (c is TabControl)
{
TabControl f = (TabControl)c;
foreach (Control tab in f.Controls)
{
TabPage tabPage = (TabPage)tab;
foreach (Control control in tabPage.Controls)
{
MessageBox.Show(control.Name);
// code to go here
}
}
}
}
The Controls collection has a Find function that returns an array:
Control[] ctrls = this.Controls.Find("listView1", true);
if (ctrls.Length == 1) {
MessageBox.Show("Found " + ctrls[0].Name);
}
This will search for a control with the specified name in the controls of the specified control and all his sons.
public Control findControlbyName(String name, Control parent){
foreach (Control ctr in parent.Controls)
{
if (ctr.Name.Equals(name)) return ctr;
else return findControlbyName(name, ctr);
}
return null;
}
You just need to do:
findControlbyName("NameOfTheListView",this);

Why aren't my TextBoxes being counted?

I'm trying to change the Text in my TextBoxes in a form but I can't find out how to account for all of my TextBoxes without doing them individually...
I've tried the following code; however, my int i returns 0.
int i = 0;
foreach (Control c in this.Controls)
{
if (c.GetType().ToString() == "System.Web.UI.WebControls.TextBox")
{
i++;
((TextBox)c).Text = CleanInput(((TextBox)c).Text);
}
}
I'm just confused on how to grab all of my TextBoxes and check them...
Try this:
int i = 0;
foreach (Control c in this.Controls)
{
if (c is TextBox)
{
i++;
((TextBox)c).Text = CleanInput(((TextBox)c).Text);
}
}
If all TextBoxes are not children of "this", use a recursive method:
CleanTextBoxes(this)
private void CleanTextBoxes(Control TheControl)
{
foreach (Control c in TheControl.Controls)
{
if (c is TextBox) ((TextBox)c).Text = CleanInput(((TextBox)c).Text);
else CleanTextBoxes(c) ;
}
}

radiobuttons - test if checked - why do first 2 approaches fail?

I was wondering why below did not work as expected...
if if-statement changed to (!ctrl.checked) it returns all radio-button's names)
myForm f = new myForm();
foreach (RadioButton ctrl in f.Controls.OfType<RadioButton>())
{
if (ctrl.Checked)
MessageBox.Show(ctrl.Name);
}
I also tried
foreach (Control c in f.controls)
if (c is radiobutton)
{
if (c.Checked)
{
messagebox.show(c.name);
}
when I then put all radio-buttons in a group-box and used below code:
foreach (RadioButton c in groupBox1.Controls)
{
if (c.Checked)
{
MessageBox.Show(c.Name);
}
}
it worked fine.
what's the difference here.
any help appreciated
I'm guessing that your radio button is the child of a control other than the form. You need to recursively search for the radio buttons.
public void DisplayRadioButtons()
{
Form f = new Form();
RecursivelyFindRadioButtons(f);
}
private static void RecursivelyFindRadioButtons(Control control)
{
foreach (Control childControl in control.Controls)
{
RecursivelyFindRadioButtons(childControl);
if (childControl is RadioButton && ((RadioButton) childControl).Checked)
{
MessageBox.Show(childControl.Name);
}
}
}

Set all Labels Font before opening the Form

Before opening the form I used following code to check if its label then change the font
foreach (Label ctl in frm.Controls)
{
ctl.Font = usefontgrid;
}
But on first line return error because it check other control types such as textbox or button,etc.
How can I check if the object is only label then go to for each?
Try this;
foreach (Control c in this.Controls)
{
if (c is Label)
c.Font = usefontgrid;
}
Or
foreach (var c in this.Controls.OfType<Label>())
{
c.Font = usefontgrid;
}
Its not clear where you place this code (should be after initialize component) but try
foreach (Label ctl in frm.Controls.OfType<Label>())
{
ctl.Font = usefontgrid;
}
There is also the following Linq to do the same thing
foreach (Label ctl in frm.Controls.Where(x => x is Label))
try this.
foreach (Control ctl in frm.Controls)
{
if(ctl.GetType()==typeof(Label)){
ctl.Font = usefontgrid;
}
}
frm.controls will give all controls
You need to check whether the control is a type of Label.

Clear all controls in a ASP.NET page with a Master page

I have a asp.net page which is inherited from a master page .I want to clear all controls in this page .I tried using the bellow method .This is not working if a master page is there. Otherwise its working fine any ideas?
private void ClearControls()
{
foreach(Control c in Page.Controls)
{
foreach (Control ctrl in c.Controls)
{
if (ctrl is TextBox)
{
((TextBox)ctrl).Text = string.Empty;
}
}
}
}
try this:
public void FindAllTextBox(Control ctrl)
{
if (ctrl != null)
{
foreach (Control c in ctrl.Controls)
{
if (c is TextBox)
((TextBox)c).Text = string.empty;
FindAllTextBox(c);
}
}
}
Ex.:
Control ctrl = this.FindControl("content");
FindAllTextBox(ctrl);
You should be able to do this with Page.Form.FindControl("ContentPlaceHolder1").Controls:
foreach (Control item in Page.Form.FindControl("ContentPlaceHolder1").Controls)
{
if (item is TextBox)
{
((TextBox)item).Text = string.Empty;
}
}
This is probably because of your controls are inside of another container when you add a master page. Have you tried adding another foreach before if?
private void ClearControls()
{
foreach(Control container in Page.Controls)
{
foreach (Control c in container.Controls)
{
foreach (Control ctrl in c.Controls)
{
if (ctrl is TextBox)
{
((TextBox)ctrl).Text = string.Empty;
}
}
}
}
}
I wouldn't do it this way though. Sometimes hardcoding is better. This would use a lot of resource when called on a page that contains lots of controls.
Don't hard code:
//Recursively get all the formControls underneath the current one, be it Page, UserControl or whatever.
public static IEnumerable<Control> GetAllControls(this Control parent)
{
foreach (Control control in parent.Controls)
{
yield return control;
foreach (Control descendant in control.GetAllControls())
{
yield return descendant;
}
}
}
Then you can call it in your webform / control:
var formCtls = this.GetAllControls().OfType<TextBox>();
foreach(TextBox txtbx in formCtls)
{
//do what you gotta do ;)
}
First, use operator as instead of is and cast:
TextBox tb = ctrl as TextBox;
if (tb != null)
{
tb.Text = String.Empty;
}
Second, you can use ITextControl instead of TextBox.
And third, try next extension method:
public static IEnumerable<T> GetChildControls(this Control control) where T : Control
{
var children = (control.Controls != null) ? control.Controls.OfType<T>() : Enumerable.Empty<T>();
return children.SelectMany(c => GetChildControls(c)).Concat(children);
}
Usage:
foreach (var c in this.Page.Controls.GetChildControls<TextBox>())
{
c.Text = String.Empty;
}
I had the same problem but I think I was making it too hard. I'm using an AJAX UpdatePanel control and I just referenced that instead of going all the way up to the MasterPage. This worked for me.
foreach (Control c in UpdatePanel1.Controls)
{
foreach (Control c1 in c.Controls)
{
if (c1 is TextBox)
{
TextBox txtBox = (TextBox)c1;
txtBox.Text = "0";
}
}
}
Just keep the controls in Panel, and try the code below
foreach (Control cntrl in pnl.Controls)//pnl is panel id
{
if (cntrl is TextBox)
{
TextBox txtBox = (TextBox)cntrl;
txtBox.Text = " ";
}
}
Make a method on your .cs like this:
//Where "this" is Page.
ClearInput(this);
private void ClearInput(Control parent)
{
foreach (Control c in parent.Controls)
{
if (c.Controls.Count > 0)
ClearInput(c);
else
{
if (c is TextBox)
(c as TextBox).Text = "";
if (c is CheckBox)
(c as CheckBox).Checked = false;
if (c is DropDownList)
(c as DropDownList).SelectedIndex = 1;
}
}
}
private void EnableControls(Control control)
{
var textbox = control as TextBox;
if (textbox != null)
{
textbox.Enabled = true;
}
var dropDownList = control as DropDownList;
if (dropDownList != null)
{
dropDownList.Enabled = true;
}
var radioButton = control as RadioButton;
if (radioButton != null)
{
radioButton.Enabled = true;
}
var checkBox = control as CheckBox;
if (checkBox != null)
{
checkBox.Enabled = true;
}
foreach (Control childControl in control.Controls)
{
EnableControls(childControl);
}
}
public void getAllCtl(ControlCollection ctls)
{
foreach (Control c in ctls)
{
if (c is System.Web.UI.WebControls.TextBox)
{
//TextBox tt = c as TextBox;
////to do something by using textBox tt.
((TextBox)c).Text = string.Empty;
}
if (c is System.Web.UI.WebControls.CheckBox)
{
((CheckBox)c).Checked = false;
}
if (c is System.Web.UI.WebControls.DropDownList)
{
((DropDownList)c).SelectedIndex = -1;
}
if (c.HasControls())
{
getAllCtl(c.Controls);
}
}
}
calling in aspx.cs file as
getAllCtl(this.Form.Controls);
This is OK and tested work for all Master-child page and where ever multiple controls are contains in the page...

Categories

Resources