Utilizing XML in ColdFusion MX

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Utilizing XML in ColdFusion MX

• by Attila Domokos

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Speaker Information

• Who am I?
• Attila Domokos
• Web Programmer at a Twin Cities based web
  development company
• 2 years of ColdFusion, 5 months of CF MX
  experience
• PHP and JAVA enthusiast

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Agenda

• What is XML - the XML syntax
• Parsing the XML document
• XML element objects
• Looping through child elements
• XML search with XPath
• Generating new XML documents
• Real World Example

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What is XML?

• eXtensible Markup Language
• XML looks a bit like HTML
• XML offers a method of putting structured data
  into a text file
• XML is machine-readable, human-intelligible
• XML is license-free, platform-independent and
  well supported

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XML Syntax

• More strict than HTML
  (Proper nesting and closing tags are
  required.)
• Starts with XML declarations
• Comments take the same form as they do in HTML
  (lt!- - This is a comment - - gt)
• DTD (Document Type Definition), XDR (XML Data
  Reduced Schema) and XSD (XML Schema Definition)
  are used for describing a document
• Validation in IE 5 browsers

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An Example

• lt?xml version1.0 encodingUTF-8?gt
• lt!- - This is my first comment - -gt
• ltcompany nameMacromediagt
• ltlocation nameSan Franciscogt
• ltemployeesgt
• ltpersongtTom Cruiselt/persongt
• ltpersongtBen Fortalt/persongt
• ltpersongtNicole Kidmanlt/persongt
• lt/employeesgt
• lt/locationgt
• lt/companygt
• Preview in Browser

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Parsing the XML Document

• 1. Specify the file and its path first
  ltCFSET MyXMLFile ExpandPath(company.xml)gt
• 2. Read the XML file into a string variable
  ltCFFILE ACTIONREAD
  
  FILEMyXMLFile
  VARIABLEMyXMLCodegt
• 3. Parse the document with XMLParse() function
  into an XML object ltCFSET MyXML
  XMLParse(MyXMLCode)gt
  
  VIEW

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XML Element Objects I.

• One root element in XML documents ltCFSET
  xnCompany MyXml.XmlRootgt
• XmlName - the name of the element ltCFSET
  enCompany nCompany.XmlNamegt
• XmlAttributes contains all the attributes of
  the corresponding element ltCFSET sCompanyName
  xnCompany.XmlAttributesna
  megt VIEW

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XML Element Objects II.

• XmlChildren An array that contains all the
  immediate children of the element ltCFSET
  Locations xnCompany.XmlChildrengt
• The number of child level elements can be
  determined with the length of the array
• ltCFSET nNumLocations ArrayLen(Locations)gt
• Each item contained by this array will be
  another XML element object (has all three
  properties) VIEW

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Looping Through Child Elements

• To display all the locations in the example, you
  have to loop through the Locations array.
• ltCFLOOP FROM1 TOnNumLocations INDEXIgt
• ltCFSET xnThisLocation Locationsigt
• ltCFSET sLocationName
  xnThisLocation.XmlAttributesnamegt
• ltCFOUTPUTgtltpgtLocations i is
  ltbgtsLocationNamelt/bgtlt/pgtlt/CFOUTPUTgt
• lt/CFLOOPgt
• VIEW

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Nested Loops

• Use nested loops if you want to display the
  employees name under locations from the example
  (company.xml).
• ltCFSET arEmployees xnThisLocationemployees.X
  mlChildrengt
• ltCFSET nNumEmployees ArrayLen(arEmployees)gt
• ltCFLOOP FROM1 TOnNumEmployees INDEXjgt
• ltCFOUTPUTgtarEmployeesj.XmlTextlt/CFOUTPUTgt
• lt/CFLOOPgt
• VIEW

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XMLSearch() and XPath

• Querying an XML file is available with the
  XMLSearch() function through XPath
• XPath is a way to apply XSLT stylesheets, now
  think of it as the XML equivalent to the WHERE
  clause in SQL query
• XPath uses slashes to represent the nested
  elements

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Find Elements with XPath

• XmlSearch(MyXml, /company/location/employees/pers
  on)
• This code will find ALL the ltpersongt elements
• VIEW
• XmlSearch(MyXml, /company/location_at_nameNewton
  /employees/person)
• Youll get only the employees belonging to the
  Newton location VIEW
• XmlSearch(MyXml, /company/location_at_nameU
  RL.LocName/employees/person)
• Location name passed through URL VIEW

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Generating New XML Docs

• ltCFXMLgt tag to output XML
• ltCFXML VARIABLEMyXmlgt
  XML code
  lt/CFXMLgt
• Output the XML as a string use the ToString()
  function
• Once you have the XML code as string, you can
  save it to disk with ltCFFILEgt, upload it with
  ltCFFTPgt or send it with ltCFMAILgt
• VIEW

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Real World Example

• Get the latest articles from Macromedia
  Designer Developer Centers XML feed to your
  site!
• The XML file can be found at
• http//www.macromedia.com/desdev/resources/
• macromedia_resources.xml
• To read the file, use the ltCFHTTPgt tag
• Lets create this .cfm template together!

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Credits

• Devan Shepherd - Teach Yourself XML in 21 days -
  (2001) - SAMS
• David Hunter - Beginning XML (2000) - WROX
• Utilizing XML and XSLT in ColdFusion MX - Nate
  Weiss (2002 April) -macromedia.com