Save Data to an XML File
Usually, we save data in databases. However, if we want to make the
data more portable, we can store the data in an XML file.
Create and Save an XML File
Storing data in XML files is
useful if the data is to be sent to applications on non-Windows
platforms. Remember that XML is portable across all platforms and the data
will not need to be converted!First we will learn how to create and save an XML file. The XML file below
will be named "test.xml" and will be stored in the c directory on the server. We
will use ASP and Microsoft's XMLDOM object to create and save the XML file:
<%
Dim xmlDoc, rootEl, child1, child2, p
'Create an XML document
Set xmlDoc = Server.CreateObject("Microsoft.XMLDOM")
'Create a root element and append it to the document
Set rootEl = xmlDoc.createElement("root")
xmlDoc.appendChild rootEl
'Create and append child elements
Set child1 = xmlDoc.createElement("child1")
Set child2 = xmlDoc.createElement("child2")
rootEl.appendChild child1
rootEl.appendChild child2
'Add an XML processing instruction
'and insert it before the root element
Set p=xmlDoc.createProcessingInstruction("xml","version='1.0'")
xmlDoc.insertBefore p,xmlDoc.childNodes(0)
'Save the XML file to the c directory
xmlDoc.Save "c:\test.xml"
%>
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If you open the saved XML file it will look something like this ("test.xml"):
<?xml version="1.0"?>
<root>
<child1 />
<child2 />
</root>
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Real Form Example
Now, we will look at a real HTML form example.
We will first look at the HTML form that will be used in this example: The
HTML
form below asks for the user's name, country, and e-mail address.
This information will then be written to an XML file for storage.
"customers.htm":
<html>
<body>
<form action="saveForm.asp" method="post">
<p><b>Enter your contact information</b></p>
First Name: <input type="text" id="fname" name="fname"><br />
Last Name: <input type="text" id="lname" name="lname"><br />
Country: <input type="text" id="country" name="country"><br />
Email: <input type="text" id="email" name="email"><br />
<input type="submit" id="btn_sub" name="btn_sub" value="Submit">
<input type="reset" id="btn_res" name="btn_res" value="Reset">
</form>
</body>
</html>
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The action for the HTML form above is set to "saveForm.asp". The "saveForm.asp"
file is an ASP page
that will loop through the form fields and store
their values in an XML file:
<%
dim xmlDoc
dim rootEl,fieldName,fieldValue,attID
dim p,i
'Do not stop if an error occurs
On Error Resume Next
Set xmlDoc = server.CreateObject("Microsoft.XMLDOM")
xmlDoc.preserveWhiteSpace=true
'Create a root element and append it to the document
Set rootEl = xmlDoc.createElement("customer")
xmlDoc.appendChild rootEl
'Loop through the form collection
for i = 1 To Request.Form.Count
'Eliminate button elements in the form
if instr(1,Request.Form.Key(i),"btn_")=0 then
'Create a field and a value element, and an id attribute
Set fieldName = xmlDoc.createElement("field")
Set fieldValue = xmlDoc.createElement("value")
Set attID = xmlDoc.createAttribute("id")
'Set the value of the id attribute equal to the name of
'the current form field
attID.Text = Request.Form.Key(i)
'Append the id attribute to the field element
fieldName.setAttributeNode attID
'Set the value of the value element equal to
'the value of the current form field
fieldValue.Text = Request.Form(i)
'Append the field element as a child of the root element
rootEl.appendChild fieldName
'Append the value element as a child of the field element
fieldName.appendChild fieldValue
end if
next
'Add an XML processing instruction
'and insert it before the root element
Set p = xmlDoc.createProcessingInstruction("xml","version='1.0'")
xmlDoc.insertBefore p,xmlDoc.childNodes(0)
'Save the XML file
xmlDoc.save "c:\Customer.xml"
'Release all object references
set xmlDoc=nothing
set rootEl=nothing
set fieldName=nothing
set fieldValue=nothing
set attID=nothing
set p=nothing
'Test to see if an error occurred
if err.number<>0 then
response.write("Error: No information saved.")
else
response.write("Your information has been saved.")
end if
%>
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Note: If the XML file name specified already exists, it will be
overwritten!
The XML file that will be produced by the code above will look something like
this ("Customer.xml"):
<?xml version="1.0" ?>
<customer>
<field id="firstName">
<value>Hege</value>
</field>
<field id="lastName">
<value>Refsnes</value>
</field>
<field id="country">
<value>Norway</value>
</field>
<field id="email">
<value>mymail@myaddress.com</value>
</field>
</customer>
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