Saturday, October 1, 2011
Edit XML files using a GridView
Download source code - 2.96 KB
Introduction
This short article shows how to edit XML files using aGridView control. Additionally, the user may create new records using some text fields and a button.The XML document
Let's take a look at the structure of the XML file:<?xml version="1.0" standalone="yes"?>
<Mitarbeiter>
<ma>
<id>1</id>
<name>Florian 1</name>
<phone>345</phone>
</ma>
...
</Mitarbeiter>The document contains some records holding personal data. Each record has an ID, name, and a phone number.The web form
First, we need some controls for the web form. We need aGridView to display, edit, and delete records from the XML file. The GridView will contain two command fields: ShowEditButton and SchowDeleteButton. To create new entries, I will use three TextBox fields for the columns of the record and a Button. Here is the code for the form:<%@ Page Language="VB" AutoEventWireup="false"
CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:GridView ID="GridView1" runat="server" AllowPaging="True" PageSize="3">
<Columns>
<asp:CommandField ShowEditButton="True" />
<asp:CommandField ShowDeleteButton="True" />
</Columns>
</asp:GridView>
<br />
<br />
<br />
<asp:TextBox ID="txtId" runat="server"></asp:TextBox>
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:TextBox ID="txtTel" runat="server"></asp:TextBox><br />
<asp:Button ID="Button1" runat="server" Text="Button" /></div>
</form>
</body>
</html>Page_Load and PageIndexChanging
In thePageLoad event, I have to bind the XML file to the GridView. To do this, I created a routine BindGrid() as I need to bind the GridView multiple times. In the BindGrid method, PhysicalApplicationPath is used to get the complete path to the XML file. Here is the code:
Protected Sub Page_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Me.Load
If Page.IsPostBack = False Then
BindGrid()
End If
End Sub
Sub BindGrid()
Dim oDs As New DataSet
oDs.ReadXml(Request.PhysicalApplicationPath + "XMLFile.xml")
GridView1.DataSource = oDs
GridView1.DataBind()
End SubNext, I have to create an event handler to implement paging for the GridView. This is as easy as setting the PageIndex for the GridView to e.NewPageIndex.Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) _
Handles GridView1.PageIndexChanging
GridView1.PageIndex = e.NewPageIndex
BindGrid()
End SubDeleting records
To delete records from the file is easy. I assign theDataSource from the GridView to a DataSet object. Then I delete the record the user has selected using the DeleteButton from the GridView. Lastly, I update the XML file and call BindGrid().Protected Sub GridView1_RowDeleting(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.GridViewDeleteEventArgs) _
Handles GridView1.RowDeleting
BindGrid()
Dim oDs As DataSet = GridView1.DataSource
oDs.Tables(0).Rows(GridView1.Rows(e.RowIndex).DataItemIndex).Delete()
oDs.WriteXml(Request.PhysicalApplicationPath + "XMLFile.xml")
BindGrid()
End SubUpdating records
Updating records is a little bit more work. First, I need to set theEditIndex for the GridView using e.NewEditIndex and call BindGrid again. This has to be done in the RowEditing event:Protected Sub GridView1_RowEditing(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.GridViewEditEventArgs) _
Handles GridView1.RowEditing
GridView1.EditIndex = e.NewEditIndex
BindGrid()
End SubThen, I implement the RowCancelingEvent. Very simple: I just have to set the EditIndex to -1 and bind the GridView.Protected Sub GridView1_RowCancelingEdit(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.GridViewCancelEditEventArgs) _
Handles GridView1.RowCancelingEdit
GridView1.EditIndex = -1
BindGrid()
End SubNow I need to create the code for the RowUpdating event. When this event fires, I have to get the changed values for the record from the GridView controls into temporary variables. This is done using a cast (CType) from cells to textboxes. Using the method .Text returns the current value of the control. Maybe, using FindControl is much better. Anyway, here is the code:Protected Sub GridView1_RowUpdating(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs) _
Handles GridView1.RowUpdating
' Get the new values from the GridView controls
Dim i As Integer = GridView1.Rows(e.RowIndex).DataItemIndex
Dim strId As String = CType(GridView1.Rows(e.RowIndex).Cells(2).Controls(0), TextBox).Text
Dim strName As String = CType(GridView1.Rows(e.RowIndex).Cells(3).Controls(0), TextBox).Text
Dim strTel As String = CType(GridView1.Rows(e.RowIndex).Cells(4).Controls(0), TextBox).Text
GridView1.EditIndex = -1
BindGrid()
' Update the XML file using the new values
Dim oDs As DataSet = GridView1.DataSource
oDs.Tables(0).Rows(i).Item(0) = strId
oDs.Tables(0).Rows(i).Item(1) = strName
oDs.Tables(0).Rows(i).Item(2) = strTel
oDs.WriteXml(Request.PhysicalApplicationPath + "XMLFile.xml")
BindGrid()
End Sub When I get the changed values, I reset the EditIndex to -1 and bind the GridView. Then, I assign the DataSource from the GridView to a DataSet and update the values in the DataSet. Lastly, the new DataSet is written to the XML file.Creating new records
Lastly, I have to create new records. To do this, I use threeTextBoxes and a Button. When the button is clicked, I create a DataSet from the DataSource of the GridView. Next, I call the method Tables(0).NewRow and assign the values to the created DataRow. In the end, I Add the new DataRow to the DataSet and write the XML file using oDs.WriteXml.Protected Sub Button1_Click(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Button1.Click
BindGrid()
Dim oDs As DataSet = GridView1.DataSource
Dim oDr As DataRow = oDs.Tables(0).NewRow
oDr("id") = txtId.Text
oDr("name") = txtName.Text
oDr("phone") = txtTel.Text
oDs.Tables(0).Rows.Add(oDr)
oDs.WriteXml(Request.PhysicalApplicationPath + "XMLFile.xml")
BindGrid()
End Sub