Structs are part of the Unified API and are thus a core product feature.
Implemented by the interfaces Struct and StructBuilder in the Java
API, structs provide a way to store dynamically typed, potentially nested objects in the
content repository, and thus add the possibility of storing dynamically structured content
to the Content Server's static content type system. To
this end, the document type schema may define XML properties with the grammar name
coremedia-struct-2008. This grammar should use the XML schema
http://www.coremedia.com/2008/struct as defined in
coremedia-struct-2008.xsd.
In the ActionScript API, structs are modeled as Bean objects. They are directly
modifiable. They implement the additional interface
com.coremedia.cap.struct.Struct to provide access to their dynamic type.
Like every content property value, struct beans are provided as properties of the
ContentProperties beans. If a struct bean contains a substruct at some
property, that substruct is again represented as a struct bean.
Atomic properties of structs may be accessed just like regular bean properties. Structs can
store strings, integers, Boolean, and links to documents as well as lists of these values.
All struct properties can be read and written using the ordinary Bean
interface. As usual, lists are represented as ActionScript Array objects. Do
not modify the array returned for a list-valued property.
To modify an array, clone the array, modify the clone, and set the new value at the bean.
In the special case of lists of structs, use the methods addAt() and
removeAt() (of the struct containing the struct list) to insert or delete
individual entries in the struct list. Note that Struct objects in struct lists
represent a substruct at a fixed position of the list. For example, the Struct
objects at position 2 will contain the values of the struct previously at position 1 after
you insert a new struct at position 0 or 1.
Structs and substructs support property change events. Substructs do not support value change events. You can only listen to a single property of a substruct.
Top-level structs in the ActionScript API are never null. If a content property
is bound to an empty XML text, a struct without properties is still accessible on the
client. This makes it easier to fill initially empty struct properties.
The most convenient way to access a struct property is by means of a value expression. For
example, for navigating from a content property bean to the property bar of
the struct stored in the content property foo, you would use the property path
foo.bar. You can use these property paths in the standard property fields
provided by CoreMedia Studio. This case is shown in the following
code fragment:
<?xml version="1.0" encoding="UTF-8"?>
<exml:component xmlns:exml="http://www.jangaroo.net/exml/0.8"
xmlns="exml:ext.config"
xmlns:editor="exml:com.coremedia.cms.editor.sdk.config">
<editor:documentForm itemId="MyDocumentType">
<items>
...
<editor:stringPropertyField propertyName="foo.bar"/>
...
</items>
</editor:documentForm>
</exml:component>Example 5.18. Property paths into struct
Structs support the dynamic addition of new property values. To this end, the interface
Struct provides access to a type object implementing
com.coremedia.cap.struct.StructType through the method getType().
You can call the addXXXProperty() methods for various property types during the
initialization code that runs after the creation of a document.
public function init(editorContext:IEditorContext):void {
...
editorContext.registerContentInitializer("MyDocumentType",
initStruct);
...
}
private function initStruct(content:Content):void {
var properties:ContentProperties = content.getProperties();
var struct:Struct = properties.get('foo') as Struct;
struct.getType().addStringProperty('bar', 200);
}Example 5.19. Adding struct properties
While it is possible to add a property automatically during the first write, this is not
recommended. Some property fields cannot handle an initial value of undefined.
You should therefore only bind property fields to initialized properties.
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