how to create an asp button dynamically and add ev

问题:

I'm trying to create a button dynamically on asp.net,but I can't add the event to it.What is wrong or missing below?

Thanks in advance

$

    Button btn2 = new Button();
    btn2.ID = "btnEdit";
    btn2.Text = "Edit Member";
    btn2.Click += new EventHandler(btnEdit_Click);
    form1.Controls.Add(btn2);

I also tried like this:

$

    Button btn2 = new Button();
    btn2.ID = "btnEdit";
    btn2.Text = "Edit Member";
    btn2.Attributes.Add("OnClick","btnEdit_Click);
    form1.Controls.Add(btn2);

回答1:

read the article about the asp.net webforms life-cycle http://msdn.microsoft.com/en-us/library/ms178472.aspx. you have to create/recreate your controls everytime when loading the page (e.g. OnLoad-Method)

http://www.asp.net/web-forms/videos/aspnet-ajax/how-to-dynamically-add-controls-to-a-web-page

回答2:

I think your trying to mix server side and client side events here.

The html attribute OnClick is a client side, when a user clicks on the button it fires a piece of JavaScript The server event OnClick happens when a user clicks a button and it posts back to the server, which allows you to hook functions (server side) into that event.

Are you looking for server side or client side?

To add a client side event you can do

btn2.Attributes.Add("onclick","my_javascript_function");

To add a server side event you can do

btn2.Click += new System.EventHandler(this.MyMethod); 

Where this.MyMethod is a method already seutp to handle the server side button click.

回答3:

If I were right, you create buttons in Page_Load.

If it is check for postbacks.

if(!postback)
{
   create your buttons.
}

回答4:

Create a method for adding all Your dynamical controls as below

public void AddControls()
{
    Button btn2 = new Button();
    btn2.ID = "btnEdit";
    btn2.Text = "Edit Member";
    btn2.Click += new EventHandler(btnEdit_Click);
    form1.Controls.Add(btn2);
}

and then call that method in Page_Load() Event & out side of the IsPostBack block as below

protected void Page_Load(object sender, EventArgs e)
{

    if (!IsPostBack)
    {

    }
    AddControls();
}

because for dynamically added control's view state will not load before Page_Load() evnt. go through this link for more info http://msdn.microsoft.com/en-us/library/vstudio/hbdfdyh7(v=vs.100).aspx

回答5:

This should do the trick:

protected void Page_Load(object sender, EventArgs e)
{
    Button b = new Button() { ID = "btnEdit", Text = "Edit Member" };
    b.Click += (sd, ev) => {
        // Do whatever you want to be done on click here.
        Button me = (Button)sd; // This creates a self-reference to this button, so you can get info like button ID, caption... and use, like this:
        me.Text = "Yay! You clicked me!";
    };
    form1.Controls.Add(b);
}