Have you ever needed to create data nodes in the Data DOM on-the-fly? How about a need to parse XML obtained from a web service data connection in order to find a value for some property? If that’s the case, then you’ll find-out how to do it in this article.

Creating Data Nodes

In a similar article, John Brinkman showed how to create form variable nodes at runtime however what’s not obvious about data nodes is that you don’t create them using

a class name of your choice.

For example, say you wanted to create the following data node structure:

<custom>
    <message>Hello World!</message>
</custom>

 

Given the following syntax for the createNode() function (see page 367 in the LC Designer 8.2 Scripting Reference):

{model}.createNode(className [, name, namespace]);

you might try the following, using “custom” as the class name for the first group/container node <custom>:

var n = createNode("custom");

Doing the above would generate an error stating that “custom” is an invalid node type.

The trick here is that only specific XFA class names are allowed, such as “text”, “decimal”, “integer”, etc., as well as two special types for data nodes: “dataGroup” and “dataValue”. When you need a data node that will contain other data nodes, you use the “dataGroup” class. When you need a data node to which you will assign a value, you use the “dataValue” node.

The JavaScript code to create the above XML structure then becomes:

// <custom> data group to contain <message>
var c = xfa.datasets.createNode("dataGroup", "custom");
// <message> data value for "Hello World!"
var m = xfa.datasets.createNode("dataValue", "message");
// set value of data value node
m.value = "Hello World!";
// add <message> into <custom> data group node
c.nodes.append(m);
// print result to JavaScript Console (Ctrl + J in Acrobat)
console.println(c.saveXML("pretty"));

// output from above:

<custom>
    <message>Hello World!</message>
</custom>

Note that the createNode() function must be called on an object of type “model” and since we’re creating nodes in the Data DOM, we use the xfa.datasets object since it is a model object.

At this point, the <custom> node (and the nodes/values it contains) is not part of the Data DOM. To add it to the Data DOM so that it gets submitted with the rest of the form’s data, you would have to append it to a node inside the root subform (the top-most subform in the Hierarchy palette). For example, if your root subform’s name was “form1”, you would do the following to add the <custom> node to the form’s data:

xfa.datasets.data.form1.nodes.append(c);

This can be very useful. In fact, this technique is used in Correspondence Management letter template scripts to flag a selection list’s default selection as having been processed. Since the data merged into the list to print the letter based on the template may not match the default selection in the list, the scripts generate a special node directly in the Data DOM to indicate whether the list’s data value should be processed instead of its default selection (i.e. no need for a hidden checkbox field for each list, keeping the form/PDF file size down).

The “Custom Node Example” section in my sample form demonstrates the above technique.

Loading Data Nodes

Another use for creating data nodes is they give you the ability to load existing XML in order to parse it without having to modify the Data DOM. If you create a new, orphaned (un-parented) data group node, you can use its loadXML() function to load an XML string into it, thereby giving you a handy XML node structure for parsing.

One example use of this would be in a form that retrieves various settings from a web service data connection where the structure of the returned data is determined by the input parameters (i.e. you have a single data connection which you can use to retrieve various data). You can return the XML data as a string and load it into a new data group node in order to parse-out the value you’re looking for without ever touching the Data DOM.

Another example would be an extension of my URL Request article. In this case, you could pass some XML data into your form via the URL request if your PDF form was available on a website. Warning: This is a not a secure method to pass data to your form.

Clicking the following link will load some movie data into the “Movies loadXML() Example” section of my sample form:

CreateLoadDataNodes.pdf?data=%3Cmovies%3E%3Cmovie%3E%3Ctitle%3ENacho%20Libre%3C%2Ftitle%3E%3Ccost%3E21.00%3C%2Fcost%3E%3CactorName%3EJack%20Black%3C%2FactorName%3E%3CcatName%3EComedy%3C%2FcatName%3E%3C%2Fmovie%3E%3Cmovie%3E%3Ctitle%3EMI%3AI%3C%2Ftitle%3E%3Ccost%3E20.00%3C%2Fcost%3E%3CactorName%3ETom%20Cruise%3C%2FactorName%3E%3CcatName%3EAction%3C%2FcatName%3E%3C%2Fmovie%3E%3C%2Fmovies%3E

Finally, my sample form also has a handy “URI Encoding Tool” section which you can use to encode various strings to include in a website address (as above).

Samples

Download Sample [pdf]

Minimum Sample Requirements: I created this sample using Designer 8.2 and Acrobat 9 however it should work fine back to Acrobat 7.0.5.

There is also a great example on creating data nodes on page 438 of the LiveCycle Designer ES Scripting Reference for Designer 8.2 — an excellent XFA form scripting reference.

---

Posted by Stefan Cameron on June 1st, 2009
Filed under CM,Data Binding,Instance Manager,Scripting,Tables,Tutorials,XFA
Both comments and pings are currently closed.

---