Object Mappings

Object mapping allows you to establish connections between objects belonging to heterogeneous models and diagrams. You create mappings between objects to model O/R (Object-Relational) mappings, which associate classes with tables to store OOM objects into a relational database, or simply to express a correspondence between objects in different models.

The following table lists the supported types of model-to-model mapping in PowerDesigner:

Source Model	CDM Target	LDM Target	PDM Target	OOM Target	XSM Target
CDM	X	X	X	X
LDM	X	X	X	X
PDM	X	X	X	X	X
OOM	X	X		X	X
XSM					X

Note: Mappings are also used to define data replications in the DMM. For more information, see Data Movement Modeling > Data Movement Diagrams > Replication Processes (DMM).

You can create mappings:

in the Mapping Editor - which gives you a global view of all the mappings to objects in the current (target) model (see The Mapping Editor)
on the Mapping tab of the property sheet of the target object (see Creating Mappings from an Object's Property Sheet)
During model generation, by selecting the Generate Mappings option in the Model Generation Options window (see Generating Models).

Each mapping is recorded in a query, a textual expression or an XPATH expression defined in the target object, which permits the selection of data from the data source and its transfer to the target model. You can view and refine these mappings in the Mapping Editor.

The following tables list the objects that can be mapped for each kind of model.

CDM Mappings

CDM objects can be mapped to other model objects as follows:

CDM Source Objects	CDM Target Objects	LDM Target Objects	PDM Target Objects	OOM Target Objects
Entity	Entity, Association, Relationship	Entity, Relationship	Table	Class, Association
Entity attribute	Entity attribute, Association attribute	Entity attribute	Column	Class attribute
Relationship	Entity, Association, Relationship	Entity, Relationship	Table, Reference	Class, Association
Inheritance	Inheritance	Inheritance	-	-
Inheritance attribute	Inheritance attribute	Inheritance attribute	-	-
Association	Entity, Association	Entity, Relationship	Table, Reference	Class, Association
Association Attribute	Association attribute, Entity attribute	Entity attribute	Column	Attribute
Data item	Data item	-	-	-
Domain	Domain	Domain	Domain	Domain

Note: You can map inheritances with CDM objects only when its child entities are not generated, i.e. when the "Generate children" option is deselected in the Generation tab of the inheritance property sheet.

LDM Mappings

LDM objects can be mapped to other model objects as follows:

LDM Source Objects	CDM Target Objects	LDM Target Objects	PDM Target Objects	OOM Target Objects
Entity	Entity, Relationship, Association	Entity, Relationship	Table	Class, Association
Entity attribute	Entity attribute	Entity attribute	Column	Attribute
Relationship	Entity, Relationship	Entity, Relationship	Table, Reference	Class, Association
Inheritance	Inheritance	Inheritance	Reference	Generalization
Inheritance attribute	Inheritance attribute	Inheritance attribute	-	-
Domain	Domain	Domain	Domain	Domain

PDM Mappings

PDM objects can be mapped to other model objects as follows:

PDM Source Objects	CDM Target Objects	LDM Target Objects	PDM Target Objects	OOM Target Objects	XSM Target Objects
Table	Entity, Relationship	Entity, Relationship	Table, Fact,Dimension	Class, Association	Element, Complex type
Table column	Entity attribute	Entity attribute	Table column, Measure, Dimension attribute	Attribute	Element, Complex type
View	-	-	Fact,Dimension	Class	-
View column	-	-	View column, Table column, Measure, Dimension attribute	Attribute	-
Reference	Relationship	Relationship	Reference	Class, Association	-
Domain	Domain	Domain	Domain	Domain	-

OOM Mappings

OOM objects can be mapped to other model objects as follows:

OOM Source Objects	CDM Target Objects	LDM Target Objects	OOM Target Objects	XSM Target Objects
Class	Entity, Association, Relationship	Entity, Relationship, Inheritance	Class	Element, complex type
Attribute	Entity attribute, Association attribute	Entity attribute, Inheritance attribute	Attribute	Element, Complex type
Generalization	-	Inheritance	Generalization	-
Association	Association	Entity, Relationship	-	-
Domain	Domain	Domain	Domain	-

XSM Mappings

XSM elements and complex types and their attributes can only serve as source objects for mapping to other XSM elements, complex types and attributes, but they can serve as the targets for mappings from OOM or PDM source objects.

Creating a Data Source
A data source provides a connection to one or more other models for mappings and (in the PDM) can also provide a connection to a database. You are prompted to create a data source with a wizard the first time you open the Mapping Editor or click the Create Mapping tool on an object property sheet Mappings tab.
The Mapping Editor
The Mapping Editor provides a graphical interface for creating and viewing mappings between models or between metamodels. It provides a global view of all the mappings to objects in your model, allowing you to quickly identify those which are mapped and unmapped.
Creating Mappings from an Object's Property Sheet
You can create mappings to an individual object on the Mapping tab of its property sheet. Mappings created in this way will be visible the next time you open the Mapping Editor.
Object and Sub-Object Mapping Properties
Mappings are sub-objects of the target object on which they are defined. Mappings do not have diagram symbols or Browser entries, and are only accessible from the Mapping Editor or from the Mapping tab of their parent object property sheet.
Metamodel Mapping Properties
Metamodel mappings are mappings between metamodel objects, which control how objects are imported or generated. Metamodel mappings are sub-objects of the PowerDesigner metamodel object on which they are defined.
Metamodel Object Properties
To view the properties of metaclasses, metaattributes, and metacollections displayed in the Mapping Editor, double-click the object node in the Mapping Editor or right-click the node and selecting Properties.

Parent topic: Linking and Synchronizing Models