Difference between revisions of "Working with the Lianja Object Model"

Latest revision as of 11:21, 4 May 2020

See Also

Understanding the Lianja App Architecture

Overview

Lianja Apps are built out of pages. Pages are built out of sections. There are a wide variety of built-in sections. Form sections for example are made up of FormItems and Gadgets. So as we can see, a Lianja App consists of a hierarchy of visual elements. This hierarchy we will refer to as the Lianja Object Model (LOM).

You can consider the whole of the Lianja App Builder as a meta-framework that you can use to develop Apps with.

As a developer you can manipulate the properties and call methods on any of these visual elements in both development and runtime mode. This is accomplished using the Lianja system object in any if the supported scripting languages: Lianja/Visual FoxPro, Python, PHP or JavaScript.

The following examples are provided in Visual FoxPro syntax but they will work equally as well in Python, PHP or JavaScript.

Lianja.getElementByID()

You can obtain a reference to the visual elements that make up your App using Lianja.getElementByID(item).

Examples

To get a reference to a page with the id mypage.

oItem = Lianja.getElementByID("mypage")

To get a reference to a section with the id mysection contained within the page mypage.

oItem = Lianja.getElementByID("mypage.mysection")

To get the current text in a FormItem with the id myitem in the section mysection contained within the page mypage use the following.

oItem = Lianja.getElementByID("mypage.mysection.myitem")
cValue = oItem.value

Note: The synonyms Lianja.get(item) and Lianja.findElementByID(item) are also available.

Lianja.item()

Alternatively, use Lianja.item(position) to obtain a reference to the page at the specified position. This can be used with Lianja.count, which returns the total number of pages in the current App.

Pages and Sections also support the count property and the item() method, allowing you to traverse the complete LOM.

Example

for i=1 to Lianja.count
    oPage = Lianja.item(i)
    ? oPage.id
    for j=1 to oPage.count
        oSection = oPage.item(j)
        ? oSection.id
        for k=1 to oSection.count
            oFormitem = oSection.item(k)
            ? oFormitem.id
        endfor
    endfor
endfor

Lianja.getElementByControlsource()

From v5.3 the Lianja.getElementByControlsource(cSource) method offers an alternative way to reference data-bound UI formitems (Canvas Section advanced controls, fields and gadgets).

The cSource corresponds to the formitem's Data source.

Example

oItem = Lianja.getElementByControlsource("customers.customerid")
cValue = oItem.value

Note: The synonym Lianja.getControlSource(cSource) is also available.

Class Reference

The Lianja System Object

The Lianja Page Object (PageBuilder)

The Lianja Section Object

The Lianja FormItem Object

The Lianja Grid Object

The Lianja WebView Object

The Lianja Editor Object (Editbox)