Two-way databinding enables you to extract values from a template.
You can use a two-way databinding expression not only to display the value of a data item, but also to update the value of a data item.
File: ProductForm.cs
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Collections.Specialized;
namespace myControls
{
public class ProductForm : CompositeControl
{
public event EventHandler ProductUpdated;
private IBindableTemplate _editItemTemplate;
private ProductFormItem _item;
private IOrderedDictionary _results;
public IOrderedDictionary Results
{
get { return _results; }
}
public string Name
{
get
{
EnsureChildControls();
return _item.Name;
}
set
{
EnsureChildControls();
_item.Name = value;
}
}
public decimal Price
{
get
{
EnsureChildControls();
return _item.Price;
}
set
{
EnsureChildControls();
_item.Price = value;
}
}
[TemplateContainer(typeof(ProductFormItem), BindingDirection.TwoWay)]
[PersistenceMode(PersistenceMode.InnerProperty)]
public IBindableTemplate EditItemTemplate
{
get { return _editItemTemplate; }
set { _editItemTemplate = value; }
}
protected override void CreateChildControls()
{
_item = new ProductFormItem();
_editItemTemplate.InstantiateIn(_item);
Controls.Add(_item);
}
protected override bool OnBubbleEvent(object source, EventArgs args)
{
_results = _editItemTemplate.ExtractValues(_item);
if (ProductUpdated != null)
ProductUpdated(this, EventArgs.Empty);
return true;
}
}
public class ProductFormItem : WebControl, IDataItemContainer
{
private string _name;
private decimal _price;
public string Name
{
get { return _name; }
set { _name = value; }
}
public decimal Price
{
get { return _price; }
set { _price = value; }
}
public object DataItem
{
get { return this; }
}
public int DataItemIndex
{
get { return 0; }
}
public int DisplayIndex
{
get { return 0; }
}
}
}
File: Default.aspx
<%@ Page Language="C#" %>
<%@ Register TagPrefix="custom" Namespace="myControls" %>
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
void Page_Load()
{
if (!Page.IsPostBack)
{
ProductForm1.Name = "Laptop";
ProductForm1.Price = 433.12m;
ProductForm1.DataBind();
}
}
protected void ProductForm1_ProductUpdated(object sender, EventArgs e)
{
lblName.Text = ProductForm1.Results["Name"].ToString();
lblPrice.Text = ProductForm1.Results["Price"].ToString();
}
Show ProductForm
Runat="server" OnProductUpdated="ProductForm1_ProductUpdated">
Text="Product Name:"
AssociatedControlID="txtName"
Runat="server" />
Text='<%# Bind("Name") %>'
Runat="server" />
Text="Product Price:"
AssociatedControlID="txtPrice"
Runat="server" />
Text='<%# Bind("Price") %>'
Runat="server" />
Text="Update"
Runat="server" />
New Product Name:
Runat="server" />
New Product Price:
Runat="server" />