Manejo de Eventos TreeView - Ejemplo

EJEMPLO - EVENTOS TREEVIEW

Las listas 7.7 y 7.8 dan un código completo para un ejemplo de página de selección TreeView, como muestra las figuras 1 y 2. Estas figuras también ilustran sus nodos productos usando check boxes. El usuario puede también checkear uno o mas de estos boxes, y entonces clickear el boton comprar.

Figura 1 Ejemplo de manejo de árbol selección de nodos

Figura 2 TreeEventHandling.aspx

Listing 7.7 TreeEventHandling.aspx

Listing 7.8 TreeEventHandling.aspx.cs

using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class TreeEventHandling : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// Fill tree with data
FillTree();
// Let's begin with all the nodes collapsed as well
treeMain.CollapseAll();
}
}
///

/// Helper method to fill tree with data
///

private void FillTree()
{


// Get all the groups and iterate through them
string[] groups = ProductCatalog.GetGroups();
foreach (string grp in groups)
{
// Create the node for the group
TreeNode groupNode = new TreeNode(grp);
// For each group get their subheadings and process them
string[] subheadings =
ProductCatalog.GetSubHeadingsByGroup(grp);
foreach (string sub in subheadings)
{
// Create the node for the subheading
TreeNode subheadingNode = new TreeNode(sub);
// For each subheading, get their products
// and process them
Product[] products =
ProductCatalog.GetProductObjectsBySubHeading(sub);
foreach (Product prod in products)
{
// Create new product tree node
TreeNode productNode = new TreeNode(prod.Name);
// Set the node's value to the product id
productNode.Value = prod.Id.ToString();
// Add product node to its parent
subheadingNode.ChildNodes.Add(productNode);
}

// Add subheading node to its parent
groupNode.ChildNodes.Add(subheadingNode);
}
// Add group node to its parent
treeMain.Nodes.Add(groupNode);
}
}
///

/// Handles the tree node selection event
///

protected void SelectProduct(object sender, EventArgs e)
{
// Get the tree node that was selected
TreeNode node = treeMain.SelectedNode;
// Only process selection if a leaf node selected
if (node.ChildNodes.Count == 0)
{

// Retrieve the product id that we placed in the node
int id = Convert.ToInt32(node.Value);
// From that product id get the product
Product prod = ProductCatalog.GetProductById(id);

// If this is a valid product, display details
if (prod != null)
{
txtId.Text = prod.Id.ToString();
txtIsbn.Text = prod.Isbn;
txtName.Text = prod.Name;
txtPrice.Text = String.Format("{0:c}", prod.Price);
}
}
}
///

/// Handles the purchase button click event
///

protected void btnPurchase_Click(object sender, EventArgs e)
{
// Handle the fact there may be no checked products
if (treeMain.CheckedNodes.Count <= 0)

labChoose.Text =

"You did not choose any products to purchase";

else

{

labChoose.Text = "You have selected the following products:";

double total = 0.0;

bulSelected.Items.Clear();

// Loop through each checked node

foreach (TreeNode node in treeMain.CheckedNodes)

{

// Retrieve the product info about this node int id = Convert.ToInt32(node.Value);

Product prod = ProductCatalog.GetProductById(id);

// If valid product, add it to list

// and add it to running total

if (prod != null)

{

string s = prod.Name;

s += "(" + String.Format("{0:c}", prod.Price) +

")";

ListItem item = new ListItem(s);

bulSelected.Items.Add(item);

total += prod.Price;

}

}

labTotal.Text = "Total purchase price: ";

labTotal.Text += String.Format("{0:c}", total);

}

}

}