Page properties

A page is a data structure that holds name-value pairs. A page can be contained in memory, or it can be stored in the system database. The system has many types of pages, including the following examples:

  • Data pages that are created when the data page is referenced
  • Named and unnamed pages
  • Parameter pages
  • Embedded pages
  • Clipboard pages

Clipboard pages that are not instances of a data page are called "undefined pages." To simplify the maintenance the pages, consider associating them with a data page.

A page can have an associated name, a class, and a list of unique names (with values for each of these names), and messages. In most cases, the names identify properties that are defined in the class of the page. Values can be text, or can themselves be a page or multiple pages, so the page data structure is recursive.

Pages are a highly flexible internal data structure that is used throughout the system. Application developers generally deal with specific pages in these situations:

  • As three of the 10 defined modes of properties ( Page, Page List, Page Group ) that can become part of a concrete object instance stored in the system
  • In the clipboard associated with a requestor, including a browser-based user
  • To pass parameters to, and receive results from, an activity being called (parameter page)

In addition, one page can govern an activity and is known as the primary page. If for one step in an activity, a different page is identified, that page is known as the step page.

Optionally, the report produced by a list view rule can be presented to users as a sequence of shorter pages, rather than a single long list to scroll through. Configure this option on the Organize tab of the List View form.

Page List and Page Group properties

A Page List property is an ordered list of embedded pages that are referenced by a numeric subscript, starting with 1. Page List properties are useful for holding lists of data. A Page Group property is an unordered set of pages that is referenced by a string subscript. Page Group properties are useful when you need to look up specific pages by a unique identifier and the order of the pages does not matter.

The values of Page List and Page Group properties are stored in the BLOB column, that is, these values are not columns in the database. You can use a Declare Index rule to expose Page List and Page Group properties so that you can report on them.

Page List or Page Group creation

When you create the property, set the Property Mode to Page List or Page Group. Set the PageClass to the class that represents the structure for each embedded page. For example, the standard Page Group property Work-.pyWorkParty has pages is of class Data-Party.

Ad hoc Page Lists are also created and filled when you do a database search by using the Obj-List method. Consider work objects entered by an operator. These work objects are not explicitly defined in the Operator table. You can write a query by using the Obj-List method to generate a list of records from the database.