Guide 02

GeneXus pattern concepts

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A GeneXus pattern ships a small set of definition files; KB Editor reads them to know the tree shape and property editors. Your extension supplies behavior for the dynamic parts.

Patterns/<PatternType>/
├── Definitions/
│   ├── <PatternType>.Pattern          main definition (version, generated objects, templates)
│   ├── <PatternType>Instance.xml      instance schema: element types, attributes, children
│   ├── <PatternType>CustomTypes.xml   custom type ids and their base data types
│   └── <PatternType>Settings.xml      settings schema
└── Source/ …                          the pattern's .NET implementation (your reference)

Instance schema

*Instance.xml defines each ElementType (a kind of node), its attributes (properties) and its allowed child elements. A .gxPattern instance is a tree of these.

<ElementType Name="Modes" Caption="Ins: {0}, Upd: {1}" CaptionParameters="Insert;Update">
  <Attributes>
    <Attribute Name="Insert" Type="enum{true;false;default}" DefaultValue="default" />
    <Attribute Name="Export" Type="enum{true;false;default}" DefaultValue="default" />
  </Attributes>
</ElementType>

Attribute types and their editors

`Type=`	Editor
`string` / `bool` / `int`	text / checkbox / number
`enum{A;B;C}`	static dropdown
`reference(KBObjectType)`	KB object picker
`code(Events)`	embedded code editor
`custom(<Id>)`	dynamic dropdown — your provider supplies the values

Settings vs instance

Patterns also have settings (*Settings.xml, edited as .gxPatternSettings). Custom types can appear in either — e.g. Work With's GridCustomRender custom type is used by the settings property CustomRender. The mechanism is the same: KB Editor calls your getTypeEditor(<Id>) regardless of where the property lives.

How it maps to your code

ElementType Name → PatternInstanceElement.elementType (branch on this).
instance node tag → PatternInstanceElement.tag.
custom(<Id>) → KB Editor calls getTypeEditor("<Id>") on your support.
Caption + CaptionParameters → the default label; override it via customShowElement.

You normally don't ship the schema — it comes from the user's GeneXus install/KB. Your extension provides the providers keyed by pattern type.

Next: Extensibility architecture.

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Introduction

Extensibility architecture