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Dynamic XFA/PDF to HTML – resolveNode method

#html #pdf #web #programming

Dynamic XFA forms contain JavaScript, which needs some considerable tidying up to convert into content which will run on a Browser.

In this technical article, our lead developer of FormVu (which converts Acrobat forms into standalone HTML5) gives you an insight into some of the technical issues involved. FormVu is the best tool for filling PDF forms in HTML.

An XFA form with an example of resolveNode

In this article I do an overview of some factors that have to be taken into consideration prior to implementing resolveNode subroutine in your code.

Why resolveNode?

Adobe lifecycle designer follows the Ecma Script 357 specification to represent the SOM model structure.

In a simple example:

<class>

<student><name>john</name></student>.

<student><name>david</name></student>

</class>
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In case you want to access the name of the second student, then you need to pass the query as “class.student[1].name” for access

But such an array-based access algorithm is not available in regular JavaScript; therefore, the resolveNode method is implemented to reference the node information from the ECMAScript 357 supported script.

The resolveNode method plays a major role in adding, removing, and moving subform instances on the fly:

A nice HTML implementation example of this functionality can be found in this converted example.

Have a go at trying to add and delete items from the purchase order form.

Steps to handle resolveNode function:

The following are steps that simplify the process of handling resolveNode functions.

  1. Write down the short representation of your full XFA form model by removing the internal node structure of fields, so you can track the method insertion point and the caller of the function very quickly.

  2. Always use descendant search prior to ascendant search: if you do not find the required item in descendants, then move to the ascendant nodes.

  3. Use parent-by-parent search while traversing to ascendant nodes.

  4. Check for [*] symbol: if you come across this sign, try to traverse through all the nodes that have the same named descendants of a particular node.

  5. Check for “..” symbol for descendant search and “.parent” for accessing parent node.

As you can see, it can be done, but requires a large amount of pre-processing.

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