Add array of controls to an aspx page

Question

I\'m trying to add an array of controls to an aspx page (C# code behind). These are the similar controls (search criteria for separate fields but will have the same values)

Answer 1

You should look into dynamically creating controls.

http://support.microsoft.com/kb/317794

Answer 2

Like @Mark Cidade says your best approach would be to create the controls in the code behind. They are just classes after all.

The simplest approach would be to put a control such as a placeHolder control on in the markup and then create a collection of dropdown lists in a loop, assinging each one a unique id like @Mark Cidade says.

From there it's a matter of adding them as child controls to the placeHolder or if you want them directly on the page you can add them to the page controls collection.

Answer 3

You can give them valid IDs and put them all in an array yourself:

<asp:DropDownList ID="FruitDropDown0" runat="server"/>
<asp:DropDownList ID="FruitDropDown1" runat="server"/>

protected void Page_Load(object sender, EventArgs e) {
   ListItem[] items = new ListItem[3];
   ...

   DropDownList[] lists = new DropDownList[] { FruitDropDown0
                                              ,FruitDropDown1
                                              ,...};

   foreach(DropDownList list in lists) {
      list.Items.AddRange(items);
      list.DataBind();
   }
}

Answer 4

Control.FindControl is what you're looking for. You can use it on any Control(like Page itself) to find controls via their NamingContainer. Put them e.g. in a Panel and use FindControl on it.

for (int x = 0; x < 20; x++) {
    DropDownList ddlFruit = (DropDownList)FruitPanel.FindControl("FruitDropDown" + x);
    ddlFruit.Items.AddRange(items[x]);    
}

You can also create them dynamically:

for (int x = 0; x < 20; x++) {
   DropDownList ddlFruit = new DropDownList();
   ddlFruit.ID = "FruitDropDown" + x
   ddlFruit.Items.AddRange(items[x]);  
   FruitPanel.Controls.Add(ddlFruit); 
}

You must recreate dynamically created controls on every postback at the latest in Page_Load with the same ID as before to ensure that ViewState is loaded correctly and events are triggered.

Answer 5

From your question it looks like you are trying dynamically render controls on the screen

Here is a good article on doing this.