This should work.. I think..
string ctrlName = "btnSomeButton" + someIndexValue;
this.Controls[ctrlName].Text = "Some value";
I get 'Object reference not set to an instance of an object.', the control does exist on the form. I've tried casting it.
Solution:
string ctrlName = "btnSomeButton" + someIndexValue;
Control[] ctrl = this.Controls.Find(ctrlName, True);
Button btn = (Button)ctrl[0];
btn.Text = "Some Value";
Thank you.
The control might be a nested control so you're going to have to dig deeper in the control tree of "this"
Here is a simple recursive control search tool, i wrote it without testing it but i think it should work for your needs:
private Control FindControl(Control ctr, string name)
{
Control c = null;
for (int i = 0; i < ctr.Controls.Count; i++)
{
if (string.Equals(ctr.Controls[i].ID, name, StringComparison.CurrentCultureIgnoreCase))
{
c = ctr.Controls[i];
break;
}
if (ctr.Controls[i].Controls.Count > 0)
{
c = FindControl(ctr.Controls[i], name);
if (c != null)
break;
}
}
return c;
}
Are your buttons actually controls on the form, or do they have a different parent? For instance, if you buttons reside inside a a Panel or GroupBox you will not be able to access them by name by just using this. You will need to find them in their container.
Example: myPanel.Controls[ctrlName].Text = "Some Value"
You can use the control methods in addition to this below to determine where the control is located i.e. what parent might have this control assigned.
{
Control[] ctls = this.Controls.Find("Button2", true);
if (ctls.Length > 0)
{
Button btn = ctls[0] as Button;
if (btn != null)
btn.PerformClick();
}
else
MessageBox.Show("Not Found");
}
private void button2_Click(object sender, EventArgs e)
{
MessageBox.Show("Button2 Clicked");
}
Depending on your requirements, you may want to consider creating a Dictionary<string, Control> collection that allows you to quickly refer to the control by name. This also frees you from requiring the control name containing the index.
Do you really have a control named like ctrlName in your immediate Controls collection? It may be the name of a control that is deeper in the hierarchy, or even a control which doesn't exist.
Try finding the control recursively:
string ctrlName = "btnSomeButton" + someIndexValue;
Control[] matchingControls = this.Controls.Find(ctrlName, true);
foreach (Control c in matchingControls)
c.Text = "Some value";
Related
I have a Placeholder and I have a dynamically created panel in the placeholder, I also have some dynamically added radio buttons in the panel, now I can usefindControl() to find the radio buttons if they are direct children of the placeholder.
I've literally spent the whole of yesterday trying to find them when they are the child elements of the Panel. How is there a way to do this?
Here's my code below:
PlaceHolder1.Controls.Add(myPanel); //add the panel to the placeholderenter code here
myPanel.Controls.Add(myRadioButton); //add the radiobutton to the panel
You should make method that recursively searches for a control using it's Id. That mean that the method will search for a control inside of (in your case) placeholder. If method finds control, it will return it. If not, it will go search every placeholder's subcontrol, going "deeper". And then, if nothing is found, it will search one more level down, in every placeholder subcontrols' subcontrol etc.)
private Control FindControl(string ctlToFindId, Control parentControl)
{
foreach (Control ctl in parentControl.Controls)
{
if (ctl.Id == ctlToFindId)
return ctl;
}
if (ctl.Controls != null)
{
var c = FindControl(ctlToFindId, ctl);
if (c != null) return c;
}
return null;
}
and then use it like this:
Control ctlToFind = FindControl(myRadioButton.Id, Placeholder1);
if (ctlToFind != null)
{
//your radibutton is found, do your stuff here
}
else
{
// not found :(
}
Finding Controls recursive is an option, but it also has a couple of down-sides.
If you know the ID's of all the controls you can just use FindControl
RadioButtonList myRadioButton = PlaceHolder1.FindControl("Panel1").FindControl("RadioButtonList1") as RadioButtonList;
Label1.Text = myRadioButton.SelectedValue;
But you will need to give your dynamically added controls an ID.
Panel myPanel = new Panel();
myPanel.ID = "Panel1";
RadioButtonList myRadioButton = new RadioButtonList();
myRadioButton.ID = "RadioButtonList1";
PlaceHolder1.Controls.Add(myPanel);
myPanel.Controls.Add(myRadioButton);
I am working on winform application in asp.net using c#. I have 10 labels on my winform created in the designer mode, called Label0 to Label9. Now I want to change the Text property of all the labels at once as per the data I acquire in the middle of execution of my program.
i want to do something like this :
for (int i = 0; i < 10; i++)
{
Label[i].Text = "Hello, this is label: "+ i.ToString();
}
Now, of course this won't work. But how can this be done? how can i call the label like its done in an array? If not possible, then what can be the best alternative solution for my problem?
If you are talking about WinForms, then you can do like this:
private void Form1_Load(object sender, EventArgs e)
{
// Form1_Load is just sample place for code executing
for (int i = 1; i < 10; i++)
{
var label = Find<Label>(this, "label" + i);
label.Text = "Hello, this is label: " + i.ToString();
}
}
private T Find<T>(Control container, string name)
where T : Control
{
foreach (Control control in container.Controls)
{
if (control is T && control.Name == name)
return (T)control;
}
return null;
}
This code will search label in form controls, and then return it based on control name and type T. But it will use just parent form. So if your label is in some panel, then you need to specify panel as container parameter. Otherwise Find method can be updated as recursive method, so it will search inside all form subcontrols, but if there will be two Label1 controls, then it will return just first one, that might be not correct.
If you can put all Label on a panel after the you can use below code to change the text
foreach (Control p in panal.Controls)
if (p.GetType == Label)
p.Text = "your text";
in my application im submitting a data to the db on a tabControls page(page:tabPage2) and i want when hitting the submit button first saving data to db(im achieving this) the a question will ask anything will be done? if the user hit the no button all fields on tabpage2 will reset. so i wrote a script like below but it is not clearing fields.
if (dr == DialogResult.Yes)
{
for (int i = 0; i < this.tabControl1.Controls.Count; i++)
{
if (this.tabControl1.SelectedTab == tabPage2)
{
if (tabPage2.Controls[i] is TextBox)
{
tabPage2.Controls[i].Text = "";
}
if (tabPage2.Controls[i] is ComboBox)
{
tabPage2.Controls[i].Text = "";
}
if (tabPage2.Controls[i] is PictureBox)
{
tabPage2.Controls[i].Text = "";
}
if (tabPage2.Controls[i] is RadioButton)
{
tabPage2.Controls[i].Text = "";
}
}
}
}
If you control the class for the page layout within the specific tab page you want to clear, it's probably best to create a public or internal method in that class (such as Clear()) which can access each of its member controls and clear them directly. That's the easiest approach, and it should usually apply.
If you instead need it to handle a page with an unknown structure, you might need an approach like:
private void ClearControls(Control parentControl)
{
foreach (Control ctrl in parentControl.Controls)
{
TextBox ctrlText;
ComboBox ctrlCombo;
PictureBox ctrlPicture;
RadioButton ctrlRadio;
// Pay careful attention to the parentheses...
if ((ctrlText = ctrl as TextBox) != null)
{
ctrlText.Text = string.Empty;
}
else if ((ctrlCombo = ctrl as ComboBox) != null)
{
ctrlCombo.SelectedIndex = -1;
}
else if ((ctrlPicture = ctrl as PictureBox) != null)
{
// Logic to clear a PictureBox called ctrlPicture
}
else if ((ctrlRadio = ctrl as RadioBox) != null)
{
// Logic to clear a RadioButton called ctrlRadio
}
else if (ctrl.Controls.Count > 0)
{
ClearControls(ctrl); // Recursively clear contained controls.
}
}
}
With a call to start it off from the original handler:
if (dr == DialogResult.Yes)
ClearControls(this.tabControl1);
You are itering over the collection of TabControl child controls, not actual TabPage's.
Change your code to this instead:
if (dr == DialogResult.Yes && this.tabControl1.SelectedTab == tabPage2)
{
foreach (var ctrl in tabPage2.Controls)
{
if (ctrl is TextBox || ctrl is ComboBox || ctrl is PictureBox || ctrl is RadioButton)
{
ctrl.Text = "";
}
}
}
I should say though than setting the Text property to "" for controls other than TextBox feels rather wrong to me. As you'll find out, this won't work for combos, images and radio buttons.
Also if you have controls nested into panels or the like they won't be cleared. Containers have their own nested collection of controls, which in turn can also be containers, and so on and on.
IMHO it would be far better for you to explicitely reset form controls one by one rather than trying to find them dynamically on your form. This way you'll be free to move your controls around at design time without ever worrying about breaking the resetting logic.
Additional suggestion: you can also attach your controls at design time to an instance of your own IExtenderProvider component which will take care of resetting controls appropriately based on their type.
I am trying to change the Visible state of controls from the form shown event.
I am reading the name of the controls from the database table and accessing it using this.Controls["controlname"].Visible. But some of the controls are not able to access from within this event. It is showing exception.
How can I access the controls from form shown event?
Use Controls.Find() to search for it. As scheien pointed out, the control is probably inside a different container causing it not to be "found" with your original syntax. Here's a quick example:
private void Form1_Shown(object sender, EventArgs e)
{
string ctlNameFromDatabase = "textBox1";
Control[] matches = this.Controls.Find(ctlNameFromDatabase, true);
if (matches.Length > 0)
{
// ... do something with "matches[0]" ...
// you may need to CAST to a specific type:
if (matches[0] is TextBox)
{
TextBox tb = matches[0] as TextBox;
tb.Text = "Hello!";
}
}
else
{
MessageBox.Show("Name: " + ctlNameFromDatabase, "Control Not Found!");
}
}
EDIT:
For MenuItems you'll have to flag the control name in the database as a "menu item" and then use this code, where menuStrip1 is the name of your MenuStrip, to find them:
string menuName = "copyToolStripMenuItem";
ToolStripItem[] matches = menuStrip1.Items.Find(menuName, true);
if (matches.Length > 0)
{
matches[0].Visible = true;
}
The same code will work for ToolStrips as well. For example, replace menuStrip1 with toolStrip1.
I'm creating a multi-tabbed .NET application that allows the user to dynamically add and remove tabs at runtime. When a new tab is added, a control is added to it (as a child), in which the contents can be edited (eg. a text box). The user can perform tasks on the currently visible text box using a toolbar/menu bar.
To better explain this, look at the picture below to see an example of what I want to accomplish. It's just a mock-up, so it doesn't actually work that way, but it shows what I want to get done. Essentially, like a multi-tabbed Notepad.
View the image here: http://picasion.com/pic15/324b466729e42a74b9632c1473355d3b.gif
Is this possible in .NET? I'm pretty sure it is, I'm just looking for a way that it can be implemented.
You could use a simple extension method:
public static void PasteIntoCurrentTab(this TabControl tabControl)
{
if (tabControl.SelectedTab == null)
{
// Could throw here.
return;
}
if (tabControl.SelectedTab.Controls.Count == 0)
{
// Could throw here.
return;
}
RichTextBox textBox = tabControl.SelectedTab.Controls[0] as RichTextBox;
if (textBox == null)
{
// Could throw here.
return;
}
textBox.Paste();
}
Usage:
myTabControl.PasteIntoCurrentTab();
I suggest you keep some "current state" variables updated so you always have a pointer to the selected Tab Page, and its child control (in the case of a tabbed-notepad emulation discussed here : a TextBox). My preference would be to keep track of the TabPage<>TextBox connections using a Dictionary to avoid having to cast the TextBoxes if they are accessed using the TabPage.Controls route : the following code assumes you have a TabControl named 'tabControl1 on a Form :
Dictionary<TabPage, TextBox> dct_TabPageToTextBox;
int tabCnt = 1;
TabPage currentTabPage;
TextBox currentTextBox;
So, as you create each new TabPage at run-time you call something like this :
private void AddNewTabPage()
{
if (dct_TabPageToTextBox == null) dct_TabPageToTextBox = new Dictionary<TabPage, TextBox>();
currentTabPage = new TabPage("Page " + tabCnt.ToString());
tabControl1.TabPages.Add(currentTabPage);
currentTextBox = new TextBox();
dct_TabPageToTextBox.Add(currentTabPage, currentTextBox);
currentTabPage.Controls.Add(currentTextBox);
currentTextBox.Dock = DockStyle.Fill;
currentTextBox.Text = "sample text for page " + tabCnt.ToString();
tabControl1.SelectedTab = currentTabPage;
tabCnt++;
}
As the end-user changes the selected TabPage you can simply update your current state variables like this :
private void tabControl1_SelectedIndexChanged(object sender, EventArgs e)
{
currentTabPage = tabControl1.SelectedTab;
currentTextBox = dct_TabPageToTextBox[currentTabPage];
MessageBox.Show("text in current Tab Page is : " + currentTextBox.Text);
}
So now have the code that is invoked by your menu choices applied only to the currentTextBox.
best, Bill
I tried this for fun ... I made a form with a ToolStripContainer, and a ToolStrip inside it, with the standard buttons (which includes the paste button). I renamed the paste button to pasteButton, and hooking everything up you get:
public Form2()
{
InitializeComponent();
TabControl tc = new TabControl();
toolStripContainer1.ContentPanel.Controls.Add(tc);
tc.Dock = DockStyle.Fill;
TextBox selectedTextBox = null;
pasteButton.Click += (_, __) => selectedTextBox.Paste(Clipboard.GetText(TextDataFormat.Text));
int pages = 0;
newTabButton.Click += (_,__) => {
TextBox tb = new TextBox { Multiline = true, Dock = DockStyle.Fill, ScrollBars = ScrollBars.Vertical };
TabPage tp = new TabPage("Page " + (++pages).ToString());
tc.Selected += (o, e) => selectedTextBox = e.TabPage == tp ? tb: selectedTextBox;
tp.Controls.Add(tb);
tc.TabPages.Add(tp);
tc.SelectedTab = tp;
selectedTextBox = tb;
};
}