Chapter 8 Working with XML Documents

Document Object Model examples

This section contains two examples illustrating XML applications of Dynamo. Subsequent sections describe the techniques employed in these examples.

Converting XML to HTML for sending to a browser

This section provides an overview of how applications can use the DOM interface. It uses the DOMNode object to process an XML document.

The document

The document below is shown with white space for readability. To reproduce this example, delete the white space between the tags.

<?xml version='1.0' ?>
<Customer>
  <FName>Jessie</FName>
  <LName>Gagliardo</LName>
  <Address>
     <Street>2800 Park Avenue</Street>
     <City>Hull</City>
     <Region Type="Province">PQ</Region>
   </Address>
</Customer>

The script

This script converts the customer information to HTML and sends it to a Web browser. The line numbers are added in comments, and are referenced in the description following the script:

<!--SCRIPT Customer.ssc                                    //1
  domDoc = toDOMDocument(document.value.xmlData );         //2
  if( domDoc == null ) {                                   //3
      document.writeln( site.GetErrorInfo() );             //4
  } else {                                                 //5
    domElement = domDoc.documentElement; // Customer node  //6
    document.writeln( "<P>Name: ");                        //7
    domElement = domElement.firstChild;                    //8
    document.writeln( domElement.firstChild.nodeValue );   //9
    domElement = domElement.nextSibling;                   //10
    document.writeln( " " + domElement.firstChild.nodeValue );//11
    domElement = domElement.nextSibling;                   //12
    document.writeln( "<P>Address: ");                     //13
    for( i = 0; i < domElement.childNodes.length ; i ++ ){ //14
        document.writeln( 
     domElement.childNodes.item(i).firstChild.nodeValue ); //15
    }                                                      //16
  }                                                        //17
-->

The output is as follows:

<P>Name: 
Jessie
 Gagliardo
<P>Address: 
2800 Park Avenue
Hull
PQ

How the script works

The script works as follows:

Line 2 An XML document is received by Dynamo, as a document value named xmlData. It is parsed to provide a DOM document object.
You can create document objects from several sources, including files on disk, documents stored in a Dynamo Web site, query results, or arguments passed in from a URL.

For more information, see "Creating the DOMDocument object".
Line 6 The node corresponding to the top element of the DOM document is accessed. Each XML document has a single top-level element that includes all other content: in this case, it is the Customer element.
Lines 8 and 9 The firstChild of the Customer element is FName. The firstChild of FName is a text node. The nodeValue of the text node is the string Jessie .
For information on navigating the document tree, see "Using nodes to work with XML documents".
Lines 10 and 11 The nextSibling of FName is LName. Line 12 writes out the string in the text node of LName (Gagliardo ).
Lines 14 to 16 These lines loop over the members of the childNodes list of the Address element, writing out the text values of each.
It is actually more efficient to use firstChild followed by nextSibling methods to loop over the children of a node than to loop over the members of the childNodes list.

Inserting data from XML into a database

XML applications can insert data from an XML document into a database. For example, you may design a Web page to contain a form that, when a button is clicked, constructs an XML document (perhaps using JavaScript) and posts it to PowerDynamo.

This section describes how to construct an INSERT statement from an XML document.

The following XML document (which has had white space added for readability) contains information for a new product, to be added to the database:

<?xml version='1.0'?>
<Products>
  <Product>
    <Name>Cricket Cap</Name>
    <Description>Cotton Cap</Description>
    <Size>One size fits all</Size>
    <Color>Blue</Color>
    <Quantity>30</Quantity>
    <Unit_Price>10</Unit_Price>
  </Product>
</Products>

The following DynaScript code takes a DOMDocument that has been constructed from this, and creates an INSERT statement from it:

function SQLVar( prod, elemname ){                                          //1
  return prod.getElementsByTagName( elemname ).item(0).firstChild.nodeValue;//2
}                                                                           //3
function InsertProduct(){                                                   //4
  var i, prod, name,  desc, size, color;                                    //5
  var quantity, unit_price, id,                                             //6
  var docElem, domDoc, xmlDoc;                                              //7
  domDoc = toDOMDocument(document.value.xmlData);                           //8
  docElem = domDoc.documentElement ;                                        //9
  sql = connection.CreateQuery();                                          //10
  id=1000; // Not a recommended way of generating ID numbers               //11
  // loop over individual product elements -- only one in this example     //12
  for( i = 0 ; i < docElem.childNodes.length ; i ++ ){                     //13
    id += 1;                                                               //14
    prod = docElem.childNodes.item(i);                                     //15
    name = SQLVar( prod , "Name" );                                        //16
    desc = SQLVar( prod , "Description" );                                 //17
    size = SQLVar( prod , "Size" );                                        //18
    color = SQLVar( prod , "Color" );                                      //19
    quantity = SQLVar( prod , "Quantity" );                                //20
    unit_price = SQLVar( prod , "Unit_Price" );                            //21
    sql.SetSQL( "INSERT INTO DBA.Product "                                 //22
    +  "VALUES ( "
    + id + ", '" + name + "', '" + desc + "', '"
    + size + "', '" + color + "', " + quantity + ", "
    + unit_price + " )" );
    if( !sql.Execute() ){                                                  //23
      document.writeln( sql.GetErrorInfo() );                              //24
    }                                                                      //25
  }                                                                        //26
}                                                                          //27

Notes

Lines 1 to 3 The SQLVar function gets the value of the named element.
For information on the getElementsByTagName method, see "Using the DOMElement object to work with elements".
Lines 8 to 9 These lines parse the document and locate the document element.
For information on the toDOMDocument function, see "Creating the DOMDocument object".
Lines 15 to 21 These lines call SQLVar to construct variables containing the quantities that need to be inserted in the database.
Line 22 The INSERT statement is constructed and executed.
Lines 23 to 25 These lines check that the INSERT was carried out successfully.