I am developing a windows application using C#. I am using DataGridView
to display data. I have added a button column in that. I want to know how can I handle click event on that button in DataGridView
.
C# – How to handle click event in Button Column in Datagridview
cdatagridviewnetwinforms
Related Solutions
Here is a very good article regarding the Mutex solution. The approach described by the article is advantageous for two reasons.
First, it does not require a dependency on the Microsoft.VisualBasic assembly. If my project already had a dependency on that assembly, I would probably advocate using the approach shown in another answer. But as it is, I do not use the Microsoft.VisualBasic assembly, and I'd rather not add an unnecessary dependency to my project.
Second, the article shows how to bring the existing instance of the application to the foreground when the user tries to start another instance. That's a very nice touch that the other Mutex solutions described here do not address.
UPDATE
As of 8/1/2014, the article I linked to above is still active, but the blog hasn't been updated in a while. That makes me worry that eventually it might disappear, and with it, the advocated solution. I'm reproducing the content of the article here for posterity. The words belong solely to the blog owner at Sanity Free Coding.
Today I wanted to refactor some code that prohibited my application from running multiple instances of itself.
Previously I had use System.Diagnostics.Process to search for an instance of my myapp.exe in the process list. While this works, it brings on a lot of overhead, and I wanted something cleaner.
Knowing that I could use a mutex for this (but never having done it before) I set out to cut down my code and simplify my life.
In the class of my application main I created a static named Mutex:
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
...
}
Having a named mutex allows us to stack synchronization across multiple threads and processes which is just the magic I'm looking for.
Mutex.WaitOne has an overload that specifies an amount of time for us to wait. Since we're not actually wanting to synchronizing our code (more just check if it is currently in use) we use the overload with two parameters: Mutex.WaitOne(Timespan timeout, bool exitContext). Wait one returns true if it is able to enter, and false if it wasn't. In this case, we don't want to wait at all; If our mutex is being used, skip it, and move on, so we pass in TimeSpan.Zero (wait 0 milliseconds), and set the exitContext to true so we can exit the synchronization context before we try to aquire a lock on it. Using this, we wrap our Application.Run code inside something like this:
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
static void Main() {
if(mutex.WaitOne(TimeSpan.Zero, true)) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
mutex.ReleaseMutex();
} else {
MessageBox.Show("only one instance at a time");
}
}
}
So, if our app is running, WaitOne will return false, and we'll get a message box.
Instead of showing a message box, I opted to utilize a little Win32 to notify my running instance that someone forgot that it was already running (by bringing itself to the top of all the other windows). To achieve this I used PostMessage to broadcast a custom message to every window (the custom message was registered with RegisterWindowMessage by my running application, which means only my application knows what it is) then my second instance exits. The running application instance would receive that notification and process it. In order to do that, I overrode WndProc in my main form and listened for my custom notification. When I received that notification I set the form's TopMost property to true to bring it up on top.
Here is what I ended up with:
- Program.cs
static class Program
{
static Mutex mutex = new Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");
[STAThread]
static void Main() {
if(mutex.WaitOne(TimeSpan.Zero, true)) {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
mutex.ReleaseMutex();
} else {
// send our Win32 message to make the currently running instance
// jump on top of all the other windows
NativeMethods.PostMessage(
(IntPtr)NativeMethods.HWND_BROADCAST,
NativeMethods.WM_SHOWME,
IntPtr.Zero,
IntPtr.Zero);
}
}
}
- NativeMethods.cs
// this class just wraps some Win32 stuff that we're going to use
internal class NativeMethods
{
public const int HWND_BROADCAST = 0xffff;
public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");
[DllImport("user32")]
public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
[DllImport("user32")]
public static extern int RegisterWindowMessage(string message);
}
- Form1.cs (front side partial)
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
protected override void WndProc(ref Message m)
{
if(m.Msg == NativeMethods.WM_SHOWME) {
ShowMe();
}
base.WndProc(ref m);
}
private void ShowMe()
{
if(WindowState == FormWindowState.Minimized) {
WindowState = FormWindowState.Normal;
}
// get our current "TopMost" value (ours will always be false though)
bool top = TopMost;
// make our form jump to the top of everything
TopMost = true;
// set it back to whatever it was
TopMost = top;
}
}
As per Prerak K's update comment (since deleted):
I guess I have not presented the question properly.
Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.
So only accessing the value so that corresponding data can be fetched from the database.
The solution you want then should look like:
UserContrl1_LOadDataMethod()
{
string name = "";
if(textbox1.InvokeRequired)
{
textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
}
if(name == "MyName")
{
// do whatever
}
}
Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:
UserContrl1_LOadDataMethod()
{
if(textbox1.text=="MyName") //<<======Now it wont give exception**
{
//Load data correspondin to "MyName"
//Populate a globale variable List<string> which will be
//bound to grid at some later stage
if(InvokeRequired)
{
// after we've done all the processing,
this.Invoke(new MethodInvoker(delegate {
// load the control with the appropriate data
}));
return;
}
}
}
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Best Answer
You've added a button to your
DataGridView
and you want to run some code when it's clicked.Easy peasy - just follow these steps:
Don'ts:
First, here's what NOT to do:
I would avoid the suggestions in some of the other answers here and even provided by the documentation at MSDN to hardcode the column index or column name in order to determine if a button was clicked. The click event registers for the entire grid, so somehow you need to determine that a button was clicked, but you should not do so by assuming that your button lives in a particular column name or index... there's an easier way...
Also, be careful which event you want to handle. Again, the documentation and many examples get this wrong. Most examples handle the
CellClick
event which will fire:...but will also fire whenever the row header is clicked. This necessitates adding extra code simply to determine if the
e.RowIndex
value is less than 0Instead handle the
CellContentClick
which only occurs:For whatever reason, the column header is also considered 'content' within a cell, so we'll still have to check for that below.
Dos:
So here's what you should do:
First, cast the sender to type
DataGridView
to expose it's internal properties at design time. You can modify the type on the parameter, but that can sometimes make adding or removing handlers tricky.Next, to see if a button was clicked, just check to make sure that the column raising the event is of type
DataGridViewButtonColumn
. Because we already cast the sender to typeDataGridView
, we can get theColumns
collection and select the current column usinge.ColumnIndex
. Then check if that object is of typeDataGridViewButtonColumn
.Of course, if you need to distinguish between multiple buttons per grid, you can then select based on the column name or index, but that shouldn't be your first check. Always make sure a button was clicked first and then handle anything else appropriately. In most cases where you only have a single button per grid, you can jump right off to the races.
Putting it all together:
C#:
VB:
Update 1 - Custom Event
If you wanted to have a little bit of fun, you can add your own event to be raised whenever a button is clicked on the DataGrid. You can't add it to the DataGrid itself, without getting messy with inheritance etc., but you can add a custom event to your form and fire it when appropriate. It's a little more code, but the upside is that you've separated out what you want to do when a button is clicked with how to determine if a button was clicked.
Just declare an event, raise it when appropriate, and handle it. It will look like this:
Update 2 - Extended Grid
What would be great is if we were working with a grid that just did these things for us. We could answer the initial question easily:
you've added a button to your DataGridView and you want to run some code when it's clicked
. Here's an approach that extends theDataGridView
. It might not be worth the hassle of having to deliver a custom control with every library, but at least it maximally reuses the code used for determining if a button was clicked.Just add this to your assembly:
That's it. Never touch it again. Make sure your DataGrid is of type
DataGridViewExt
which should work exactly the same as a DataGridView. Except it will also raise an extra event that you can handle like this: