The XMLDataDocument
There are many ways to read XML,
through the XMLTextReader and the XMLDataDocument. The XMLDataDocument thinks
of XML as data like it would be in a DataSet. For those of you with some
knowledge of how XML works in .NET, the XMLDataDocument is like the
XMLDocument and can be used anywhere it can be, but the DataDocument
automatically creates a DataSet and had more of the DataSet functions
(relationships etc.). Lets look at an example of it in use. Remember to Import
System.XML, System.Data and System.Data.OleDb
<script runat="server"
language="VB">
sub page_load(sender as object, e as eventargs)
dim xdoc as new XMLDataDocument()
xdoc.DataSet.ReadXML(Server.MapPath("books.xml"))
dg1.DataSource = xdoc.DataSet
dg1.Datamember = xdoc.DataSet.Tables(0).TableName
dg1.DataBind()
end sub
</script>
<asp:datagrid id="dg1" runat="server"
BorderColor="black" gridlines="vertical" font-name="arial"
font-size="10pt" /> |
If you look through this code you will see that
the xdoc.DataSet is just like any other DataSet, and we have put it into a
DataGrid. However, if you look at the datagrid, you can see that there are
fields like the author(s) missing. This is because the XML document has been
divided up into tables depending on these rules -
- Any elements with attributes become tables.
- Any elements that contain other elements
become tables.
- If there are two or more elements with the
dame name, they become a table.
- All direct children of the root node become
tables.
<script runat="server"
language="VB">
sub page_load(sender as object, e as eventargs)
dim xdoc as new XMLDataDocument()
xdoc.DataSet.ReadXML(Server.MapPath("books.xml"))
dg1.DataSource = xdoc.DataSet
dg1.Datamember = xdoc.DataSet.Tables(0).TableName
dg1.DataBind()
dg2.DataSource = xdoc.DataSet
dg2.Datamember = xdoc.DataSet.Tables(1).TableName
dg2.DataBind()
end sub
</script>
<asp:datagrid id="dg1" runat="server"
BorderColor="black" gridlines="vertical" font-name="arial"
font-size="10pt" />
<asp:datagrid id="dg2" runat="server" BorderColor="black"
gridlines="vertical" font-name="arial" font-size="10pt" /> |
As you can see in this table, we have taken the
two tables that it has created and put them into datagrids. You can see that
it has generated a book_Id column that identifies each <book> element which is
directly under the root <books>. Each other element or attribute is assigned
the ID of the <book> element's id that they are under, you can see that
authors can have the same book_Id and can be duplicated for different books.
This is a powerful feature, you can do anything
that you can do in a normal dataset now and can use XML data more effectively.
