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Java Open Clients
Accessing ABL ProDataSets : ProDataRelationMetaData class

ProDataRelationMetaData class

OpenEdge provides a Java class, com.progress.open4gl.ProDataRelationMetaData, that allows you to specify and access the definition of a given data-relation. A single data-relation defines a relationship between a parent ProDataObject collection and a child ProDataObject collection within a ProDataGraph. Thus, a ProDataRelationMetaData object represents schema information that is defined as part of a corresponding ProDataGraphMetaData object. To specify parent-child relationships, each data-relation names the column properties (fields) in parent and child ProDataObject types that form a primary-foreign key relationship between a given parent ProDataObject instance and one or more child ProDataObject instances.
You can use a data-relation to retrieve child records related to the parent. A parent ProDataObject instance (representing a single table row) contains a list of references to the related child ProDataObject instances (representing one or more table rows). For a each data-relation, these references are represented in every parent row as a many-valued reference property in order to support multiple child rows. After you instantiate a ProDataGraph and add all ProDataObject instances, you can then call the ProDataGraphsetChildTableReferences( ) method, which uses the specified key relationships to create all the child reference property lists in each parent ProDataObject as provided by the data-relations defined for the ProDataGraph.
A ProDataGraphMetaData object can have multiple ProDataRelationMetaData objects. Each ProDataRelationMetaData object typically maps to a particular data-relation object in a corresponding ABL ProDataSet.
Note: The requirement to map data-relations in a ProDataGraph to data-relation objects in a ProDataSet depends on whether the ProDataSet parameter is static or dynamic and what the application service expects. For more information, see the information on preparing to pass parameters using different modes in Preparing and passing ProDataSets as ProDataGraph parameters
The com.progress.open4gl.ProDataRelationMetaData class contains with the following constructors and methods.
* Constructors
* Methods