Package com.ptc.core.query.command.common

Describes the commands for queries of Windchill persistent data.

See:
Description

Class Summary

AbstractQueryCommand	This abstract class defines a command for all queries that use com.ptc.core.query services.
AttributeContainerQueryCommand	This class provies a query implementation based on the contents of an AttributeContainer.
BasicQueryCommand	This class provies a basic implementation of a query comand the results, criteria, and sort specifications are implemented as simple attributes with setters and getters.
FindPersistentEntityCommand	This Command executes a query derived from the values int the source TypeInstance.

Package com.ptc.core.query.command.common Description

Describes the commands for queries of Windchill persistent data.

Command Hierarchy

Query commands are based on the general Command subsystem architecture. Query specific commands are derived directly from commands in the Repository package.

AbstractQueryCommand

The AbstractQueryCommand specifies a query in terms of derived result, criteria, and sort specifications. The concrete subclasses implement these derived attributes.

BasicQueryCommand

BasicQueryCommand is a simple container that contains attributes for the result, criteria, and sort specifications. These attributes can be accessed via normal getter and setter methods. The criteria and sort specifications are not required. If the result specification is not explicitly set, then one will be derived from the filter attribute (inherited from AbstractServerCommand). The helper method BasicQueryCommand.appendCriteria(com.ptc.core.meta.container.common.AttributeContainerSet, boolean) can be used to add additional critieria to any existing ones.

AttributeContainerQueryCommand

AttributeContainerQueryCommand derives the specifications from the AttributeTypeIdentifiers and content of the input AttributeContainer (inherited from AbstractServerCommand). The content will generally contain either DataSet or value objects. The overall criteria are built from the AttributeContainer by constructing a CompositeAttributeContainerSet with an implicit intersection (logical AND) of criteria for each content object. The ResultSpec is simply the entire list of AttributeTypeIdentifiers in the AttributeContainer.

The AttributeContainerQueryCommand extends BasicQueryCommand so that additional query specifications can be added. A sort specification can be set and additional criteria can be added. If other criteria have been explicitly added, then the criteria derived from the AttributeContainer are combined via intersection (logical OR) when executing the query.

Criteria Augmentation

The query commands support an attribute for augmenting the criteria specified in the command. The attribute CriteriaAugmentor is used to specify an implementation that applies to every execution of the command. When the command is executed, the existing criteria are augmented with criteria generated by the CriteriaAugmentor implementation. The criterion are combined using intersection (i.e. logical AND).

The default CriteriaAugmentor implementation for all query commands is LatestCriteriaAugmentor. To override this default behavior, the NoOpCriteriaAugmentor or other applicable implementation could be set on the query command prior to execution.

Outputs

The query commands have two outputs, ResultContainer and RepositoryPagingSession. The ResultContainer holds a List of TypeInstances and is ordered as indicated by the SortSpec. The optional RepositoryPagingSession will be valid if a paging session was established as specified by the input PageMode. A valid RepositoryPagingSession can be used to fetch more results or to close the paging session. Queries can always involve paging, either implicitly or explicitly. Therefore, the result RepositoryPagingSession should always be processed to determine if all results have been obtained. See Paging Patterns for more details.