- Why XML?
- Where Do I Use XML?
- HTML Form Data to XML Conversion
- Conclusion
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HTML Form Data to XML Conversion
Our objective in this article is to suggest some simple methods to use HTML forms to construct XML documents, which can then be passed to a database or saved as a file. We will start with a simple XML document and then discuss how we can enhance the code to handle more complex XML structures.
A Simple XML Document
In this case, constructing the XML document requires iterating through the form data in the request object and writing the value of each form field as an XML Document Node.
To exclude the form fields that we do not wish to include within the XML document, we will append the string "__exclude__" to the field name in the HTML form data.
Assume that we have a simple XML document that we need to construct, as follows:
<?xml version="1.0"?> <function> <func_name>ADD_USER</func_name> <firstname>Jasmit</firstname> <middlename>Singh</middlename> <lastname>Kochhar</lastname> <address>1234 Some Dr.</address> <city>Pleasant Hill</city> <state>CA</state> <zip>94523</zip> </function>
The data is captured using the HTML form given as follows (NewUser.html):
<html>
<head><title>New User Information</title></head>
<body>
<form action="ProcessData.asp" method="post" enctype="application/x-www-form-urlencoded">
<h2>Please provide the following information</h2>
<input type="hidden" name="func_name" value="ADD_USER">
<table>
<tr><td><b>First Name:</b></td>
<td><input type="text" name="firstname" size="40"></td></tr>
<tr><td><b>Middle Name:</b></td>
<td><input type="text" name="middlename" size="40"></td></tr>
<tr><td><b>Last Name:</b></td>
<td><input type="text" name="lastname" size="40"></td></tr>
<tr><td><b>Street Address:</b></td>
<td><input type="text" name="address" size="40"></td></tr>
<tr><td><b>City, State - Zip:</b></td>
<td><input type="text" name="city" size="30">,
<input type="text" name="state" size="2">
<input type="text" name="zip" size="10"></td></tr>
<tr><td colspan="2">
<input type="submit" name="__exclude__Submit" value="Submit">
</td></tr>
</table>
</form>
</body></html>
The only difference in the preceding HTML form is the form field for the button with the name "__exclude__Submit". We wish to include all other input variables as part of the XML document generated.
The form is submitted from a user's Web browser to the Web server that sends the data to the ASP page ProcessData.asp. The details for the page are as follows:
<%
Option Explicit
'-------------------- ProcessData.asp---------------------------------
'--------------------------------------------------------------------
' The Function saveXMLData saves the XML doc in the filename specified.
' The function can be easily adapted to send the data directly to
' a database object
'--------------------------------------------------------------------
Function saveXMLData(strPath, strFileName)
'Declare local variables.
Dim aXMLDoc
Dim aRootNode
Dim aFormVar
Dim aPI
Dim Item
'Create an XMLDOM Object
Set aXMLDoc = server.CreateObject("Microsoft.XMLDOM")
aXMLDoc.preserveWhiteSpace = True
'Create the root node for the document
Set aRootNode = aXMLDoc.createElement("function")
aXMLDoc.appendChild aRootNode
'Iterate the Request Object for all form data
For Each item in Request.Form
'Do not include the variable if it contains __exclude__
If instr(1,item,"__exclude__") = 0 Then
Set aFormVar =aXMLDoc.createElement(item)
aFormVar.Text = Request.Form(item)
aRootNode.appendChild aFormVar
End If
Next
'Append the processing instruction
Set aPI = aXMLDoc.createProcessingInstruction("xml","version='1.0'")
aXMLDoc.insertBefore aPI, aXMLDoc.childNodes(0)
'Save the XML document.
aXMLDoc.save strPath & "\" & strFileName
'Release all references.
Set aXMLDoc = Nothing
Set aRootNode = Nothing
Set aFormVar= Nothing
Set item = Nothing
Set aPI = Nothing
End Function
' The page starts here
On Error Resume Next
' Save the XML Data
SaveXMLData "c:","NewUser.xml"
If err.number <> 0 then
Response.write("Errors occurred while saving your information."+ Err.Description)
Else
Response.write("Thank you for submitting your information.")
End If
%>
A More Complex XML Document
The first approach will work for very straightforward XML document that is easy to construct from the HTML form data posted. Let us consider a little more involved example of the XML document, as follows:
<?xml version="1.0"?> <function> <name>ADD_USER</name> <parameters> <firstname>Jasmit</firstname> <middlename>Singh</middlename> <lastname>Kochhar</lastname> <contactinfo> <address>1234 Some Dr.</address> <city>Pleasant Hill</city> <state>CA</state> <zip>94523</zip> </contactinfo> </parameters> </function>
The data is captured using a modified HTML form, as follows (NewUserMod.html):
<html>
<head><title>New User Information</title></head>
<body>
<form action="ProcessData.asp" method="post" enctype="application/x-www-form-urlencoded">
<h2>Please provide the following information</h2>
<input type="hidden" name="1/name" value="ADD_USER">
<table>
<tr><td><b>First Name:</b></td>
<td><input type="text" name="2../parameters/firstname" size="40"></td></tr>
<tr><td><b>Middle Name:</b></td>
<td><input type="text" name="3../middlename" size="40"></td></tr>
<tr><td><b>Last Name:</b></td>
<td><input type="text" name="4../lastname" size="40"></td></tr>
<tr><td><b>Street Address:</b></td>
<td><input type="text" name="5../contactinfo/address" size="40"></td></tr>
<tr><td><b>City, State - Zip:</b></td>
<td><input type="text" name="6../city" size="30">,
<input type="text" name="7../state" size="2">
<input type="text" name="8../zip" size="10"></td></tr>
<tr><td colspan="2">
<input type="submit" name="Submit" value="Submit">
</td></tr>
</table>
</form>
</body></html>
This form is a little different from the one we created in NewUser.html. There are three primary distinctions:
The field names start with the order in which we want them to appear in the XML string. Even though all browsers are supposed to submit the input fields in the same order as they are listed in the HTML form (per the HTTP specification), some browsers do not adhere to this rule. The count in front of the fields ensures that the order of the fields processed is retained.
The structure of the XML string is represented in the / notation for traversing a hierarchical tree. If one wants to start an element at the root node, we start the variable with a "/". If we want to process the element with the same parent as the current node, we represent that with "../". Hence, if we wanted to go two levels up, we would represent that as "../../".
Finally, any of the HTML form fields that are not to be included in the XML string are represented without any number appended to them. For example, the submit button has no order appended to it.
The form is submitted from the user's Web browser to the Web server, which sends the data to the ASP page ProcessDataMod.asp. The details for the page are as follows:
<%
Option Explicit
'-------------------- ProcessDataMod.asp------------------------------
'----------------------------------------------------------------------
' Function returns the order for the item in the HTML form to be
' considered for the construction of the XML document. The function
' also returns the name of the valiable with the order removed
'----------------------------------------------------------------------
Function getItemOrder(strItem)
'Declare the local variables
Dim totLen
Dim i
Dim strTest
Dim LoopStop
Dim order
'If the variable does not have an order indicated return order as -1
order = -1
i=1
totLen = Len(strItem)
if (totLen > 0) then
LoopStop = false
end if
DO UNTIL LoopStop
strTest = Left(strItem, i)
' Continue concatenating a character of the string till it
' is an integer
if ((isNumeric(strTest)) and (instr(strTest, ".")=0)) then
LoopStop = false
else
' The integer has ended in the string
LoopStop = true
if ( i> 1) then
' Get the integer part of the variable asthe order for the string
' and copy the rest in the original string variable
strTest = Left(strItem, i-1)
strItem = Right(strItem, totLen-i+1)
order = CInt(strTest)
end if
end if
i = i+1
LOOP
getItemOrder = order
end Function
'--------------------------------------------------------------------
' The Function saveXMLData saves the XML doc in the filename specified.
' The function can be easily adapted to send the data directly to
' a database object
'--------------------------------------------------------------------
Function saveXMLData(strPath, strFileName)
'Declare local variables.
Dim aXMLDoc
Dim aRootNode
Dim aFormVar
Dim aPI
Dim Item
Dim strItem
Dim OrdrItem
Dim aDictObj
Dim maxNum
Dim ItemsArray
Dim CurrNode
Dim NodeName
Dim i
Dim j
'Create an XMLDOM Object
Set aXMLDoc =server.CreateObject("Microsoft.XMLDOM")
aXMLDoc.preserveWhiteSpace = True
'Create the root node for the document
Set aRootNode = aXMLDoc.createElement("function")
aXMLDoc.appendChild aRootNode
' Set the root node of the document as the current node
Set currNode = aRootNode
' Use a dictionary object to store the variables from the
' html form so as to retrieve them in the indicated order
Set aDictObj =
server.CreateObject("Scripting.Dictionary")
' Store the order of the last variable in MaxNum
MaxNum = -1
' Iterate the Request Object for all form data
' and put the variables in the dictionary object
' with the key indicating their order
For Each item in Request.Form
strItem = item
OrdrItem = getItemOrder(stritem)
if (MaxNum < OrdrItem) then
MaxNum = OrdrItem
end if
if (OrdrItem > 0) then
aDictObj.Add OrdrItem, stritem
end if
Next
' Iterate to the value of the variable MaxNum
' and process each field as indicated by the
' HTML form element into corresponding leaves
' of the XML document
For i = 1 to MaxNum
if (aDictObj.exists(i)) then
strItem = aDictObj.Item(i)
' Parse the variable for all the / which indicate the level
ItemsArray = Split(stritem, "/")
For j= 0 to UBOUND(ItemsArray)
NodeName = CStr(Trim(ItemsArray(j)))
if (NodeName = "") then
' -- Get the root Node of the XML document
Set currNode = aRootNode
elseif (NodeName = "..") then
' -- Get the parent of the current node in the XML document
Set currNode = CurrNode.parentNode
else
'Create an element
Set aFormVar =aXMLDoc.createElement(NodeName)
currNode.appendChild aFormVar
Set currNode = aFormVar
end if
NEXT
' For the final leaf node get the value submitted in the HTML form
currNode.Text = Request.Form(CStr(i)+stritem)
end if
Next
'Append the processing instruction
Set aPI = aXMLDoc.createProcessingInstruction("xml","version='1.0'")
aXMLDoc.insertBefore aPI, aXMLDoc.childNodes(0)
'Save the XML document
aXMLDoc.save strPath & "\" & strFileName
'Release all object references
Set aXMLDoc = Nothing
Set aRootNode = Nothing
Set aFormVar= Nothing
Set item = Nothing
Set aPI = Nothing
Set currNode = Nothing
Set aDictObj = Nothing
End Function
On Error Resume Next
' Save the XML Data
SaveXMLData "c:","NewUserMod.xml"
If err.number <> 0 then
Response.write("Errors occurred while saving your information."+ Err.Description)
Else
Response.write("Thank you for submitting your information.")
End If
%>