Answers for Day 11 | Sams Teach Yourself ASP.NET in 21 Days (2nd Edition)


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	Sams Teach Yourself ASP.NET in 21 Days, Second Edition By Chris Payne
	Table of Contents

	Appendix A. Answers to Quiz Questions

Quiz

1:	When should you use an `XmlTextReader` versus an `XmlDocument`?
A1:	An `XmlTextReader` should be used when you only need to view data and don't need any higher-level functionality. The `XmlDocument` provides more functionality using the XML Document Object Model, but it introduces additional overhead.
2:	What does XML DOM stand for?
A1:	Extensible Markup Language Document Object Model.
3:	What's the difference between a node and an element?
A1:	An element is represented by a single tag in an XML file. A node is an entire branch of data, consisting of start and end tags, children elements, and any attributes.
4:	Will the following code snippet work? dim xmldoc as new XMLDataDocument() xmldoc.DataSet.ReadXml("books.xml")
A1:	No, the `ReadXml` requires the full path to the XML data file. The last line should read as follows: xmldoc.DataSet.ReadXml(Server.MapPath("books.xml"))

Exercises

Create a new XML file that uses the books.xdr schema. Make sure your format is correct by using ASP.NET to validate it.

Build an interface that allows users to edit XML data from a DataGrid. Be sure to write the changes back to the file.

A1:

Here's the code for the solution:

 1:    <%@ Page Language="VB" %> 2:    <%@ Import Namespace="System.Xml" %> 3:    <%@ Import Namespace="System.Data" %> 4:    <%@ Import Namespace="System.Data.OleDb" %> 5: 6:    <script runat=server> 7:       private i, j as integer 8:       private strOutput as string = "" 9:       public xmldoc as new XMLDataDocument() 10: 11:       sub Page_Load(Sender as Object, e as EventArgs) 12:          if not Page.IsPostBack then 13:             GetData() 14:             BindControl() 15:          end if 16:       end sub 17: 18:       sub UpdateBtn_Click(Sender as Object, e as EventArgs) 19:          dim Title as TextBox 20:          dim Genre as TextBox 21:          dim Style as TextBox 22:          dim Price as TextBox 23: 24:          GetData() 25: 26:          'update data 27:          For i = 0 To DataGrid1.Items.Count-1 28:             Title = DataGrid1.Items(i).FindControl("Title") 29:             Genre = DataGrid1.Items(i).FindControl("Genre") 30:             Style = DataGrid1.Items(i).FindControl("Style") 31:             Price = DataGrid1.Items(i).FindControl("Price") 32: 33:             xmldoc.DataSet.Tables(0).Rows(i)("title") = _ 34:                Title.Text 35:             xmldoc.DataSet.Tables(0).Rows(i)("genre") = _ 36:                Genre.Text 37:             xmldoc.DataSet.Tables(0).Rows(i)("style") = _ 38:                Style.Text 39:             xmldoc.DataSet.Tables(0).Rows(i)("price") = _ 40:                Price.Text 41:          Next 42: 43:          try 44:             xmldoc.Save(Server.MapPath("books.xml")) 45:          catch 46:             output.Text = "Error updating data" 47:          end try 48: 49:          BindControl() 50:       end sub 51: 52:       sub GetData() 53:          try 54:             xmldoc.DataSet.ReadXml(Server.MapPath("books.xml")) 55:          catch ex as Exception 56:             output.Text = "Error accessing XML file" 57:          end try 58:       end sub 59: 60:       sub BindControl() 61:          DataGrid1.DataSource = xmldoc.DataSet 62:          DataGrid1.DataMember = xmldoc.DataSet.Tables(0). _ 63:             TableName 64:          DataGrid1.DataBind() 65:       end sub 66:    </script> 67: 68:    <html><body> 69:       <asp:Label  runat="server" /> 70: 71:       <form runat="server"> 72: 73:       <asp:DataGrid  74:          BorderColor="black" 75:          GridLines="Vertical" 76:          width="450" 77:          Font-Name="Arial" 78:          Font-Size="10pt" 79:          HeaderStyle-BackColor="#cccc99" 80:          ItemStyle-BackColor="#ffffff" 81:          AlternatingItemStyle-Backcolor="#cccccc" 82:          AutogenerateColumns="false" runat="server" > 83: 84:          <Columns> 85: 86:             <asp:TemplateColumn HeaderText="Title"> 87:                <ItemTemplate> 88:                   <asp:TextBox  runat="server" 89:                      Text='<%# Container.DataItem("title") %>' 90:                    /> 91:                </ItemTemplate> 92:             </asp:TemplateColumn> 93: 94:             <asp:TemplateColumn HeaderText="Genre"> 95:                <ItemTemplate> 96:                   <asp:TextBox  runat="server" 97:                      Text='<%# Container.DataItem("genre") %>' 98:                      width="75px" /> 99:                </ItemTemplate> 100:             </asp:TemplateColumn> 101: 102:             <asp:TemplateColumn HeaderText="style"> 103:                <ItemTemplate> 104:                   <asp:TextBox  runat="server" 105:                      Text='<%# Container.DataItem("style") %>' 106:                      width="75px" /> 107:                </ItemTemplate> 108:             </asp:TemplateColumn> 109: 110:             <asp:TemplateColumn HeaderText="Price"> 111:                <ItemTemplate> 112:                   <asp:TextBox  runat="server" 113:                      Text='<%# Container.DataItem("price") %>' 114:                      width="50px" /> 115:                </ItemTemplate> 116:             </asp:TemplateColumn> 117: 118:          </Columns> 119:       </asp:DataGrid> 120:       <p> 121:       <center> 122:       <asp:Button  runat="server" 123:          OnClick="UpdateBtn_Click" 124:          text="Update!" /> 125:       </center> 126: 127:       </form> 128: 129:    </body></html>


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