org.kuali.rice.krad.data.util

Class ReferenceLinker

java.lang.Object

org.kuali.rice.krad.data.util.ReferenceLinker

public class ReferenceLinker
extends Object

The ReferenceLinker provides functionality that allows for ensuring that relationships and foreign key state are populated and kept in sync as changes are made to a data object.

This may include fetching relationships as keys are changed that would necessitate updating the object graph, and may also ensure that foreign key values are kept in sync in situations where a data object may have more than one field or object that stores the same foreign key.

This class has a single method linkChanges(Object, java.util.Set) which takes a data object and a list of property paths for fields which have been modified. It then uses this information determine how to link up relationships and foreign key fields, recursing through the object graph as needed.

Linking occurs from the bottom up, such that this class will attempt to perform a post-order traversal to visit the modified objects furthest from the root first, and then backtracking and linking back to the root. The linking algorithm handles circular references as well to ensure that the linking process terminates successfully.

The ReferenceLinker requires access to the DataObjectService so it must be injected using the provided setDataObjectService(org.kuali.rice.krad.data.DataObjectService) method.

Author:

Kuali Rice Team (rice.collab@kuali.org)

Constructor Summary

Constructors

Constructor and Description
ReferenceLinker()

Method Summary

Modifier and Type	Method and Description
protected List<String>	assembleLinkingPaths(Link link) Returns a list of link paths based on provided link.
protected void	cascadeLinkingAnnotations(DataObjectWrapper<?> wrapped, Map<String,Set<String>> decomposedPaths, Set<Object> linked) Gets indexes that have been modified.
protected Map<String,Set<String>>	decomposePropertyPaths(Set<String> changedPropertyPaths) Returns decomposed property paths based on changedPropertyPaths
protected Map<String,Set<String>>	decomposePropertyPaths(Set<String> changedPropertyPaths, String prefix) Returns decomposed property paths that start with the provide prefix
DataObjectService	getDataObjectService() Returns the DataObjectService used by this class
protected boolean	isPrimaryKeyModified(DataObjectMetadata metadata, Set<String> modifiedPropertyPaths) Checks if primary key can be modified.
protected void	linkBiDirectionalCollection(DataObjectWrapper<?> parentWrapper, DataObjectWrapper<?> elementWrapper, DataObjectCollection collectionMetadata) Performs bi-directional collection linking, ensuring that for bi-directional collection relationships that both sides of the relationship are properly populated.
void	linkChanges(Object rootObject, Set<String> changedPropertyPaths) Performs linking of references and keys for the given root object based on the given set of changed property paths that should be considered during the linking process.
protected void	linkChangesInternal(Object object, Map<String,Set<String>> changedPropertyPaths, Set<Object> linked) Internal implementation of link changes which is implemented to support recursion through the object graph.
protected void	linkCollectionChanges(DataObjectWrapper<?> wrapped, Map<String,Set<String>> decomposedPaths, Set<Object> linked) Link changes for collections on the given wrapped data object.
protected void	linkRelationshipChanges(DataObjectWrapper<?> wrapped, Map<String,Set<String>> decomposedPaths, Set<Object> linked) Link changes for relationships on the given wrapped data object.
void	setDataObjectService(DataObjectService dataObjectService) Specify the DataObjectService to be used during linking.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReferenceLinker

public ReferenceLinker()

Method Detail

getDataObjectService

public DataObjectService getDataObjectService()

Returns the DataObjectService used by this class

Returns:

the DataObjectService used by this class

setDataObjectService

public void setDataObjectService(DataObjectService dataObjectService)

Specify the DataObjectService to be used during linking.

The linker will use the DataObjectService to fetch relationships and query metadata.

Parameters:

dataObjectService - the DataObjectService to inject

linkChanges

public void linkChanges(Object rootObject,
                        Set<String> changedPropertyPaths)

Performs linking of references and keys for the given root object based on the given set of changed property paths that should be considered during the linking process.

The root object should be non-null and also a valid data object (such that DataObjectService.supports(Class) returns true for it). If neither of these conditions is true, this method will return immediately.

See class-level documentation for specifics on how the linking algorithm functions.

Parameters:

rootObject - the root object from which to perform the linking

changedPropertyPaths - the set of property paths relative to the root object that should be considered modified by the linking algorithm

linkChangesInternal

protected void linkChangesInternal(Object object,
                                   Map<String,Set<String>> changedPropertyPaths,
                                   Set<Object> linked)

Internal implementation of link changes which is implemented to support recursion through the object graph.

Parameters:

object - the object from which to link

changedPropertyPaths - a decomposed property path map where the key of the map is a direct property path relative to the given object and the values are the remainder of the path relative to the parent path, see decomposePropertyPaths(java.util.Set)

linked - a set containing objects which have already been linked, used to prevent infinite recursion due to circular references

linkRelationshipChanges

protected void linkRelationshipChanges(DataObjectWrapper<?> wrapped,
                                       Map<String,Set<String>> decomposedPaths,
                                       Set<Object> linked)

Link changes for relationships on the given wrapped data object.

Parameters:

wrapped - the wrapped data object

decomposedPaths - the decomposed map of changed property paths

linked - a set containing objects which have already been linked

linkCollectionChanges

protected void linkCollectionChanges(DataObjectWrapper<?> wrapped,
                                     Map<String,Set<String>> decomposedPaths,
                                     Set<Object> linked)

Link changes for collections on the given wrapped data object.

Parameters:

wrapped - the wrapped data object

decomposedPaths - the decomposed map of changed property paths

linked - a set containing objects which have already been linked

linkBiDirectionalCollection

protected void linkBiDirectionalCollection(DataObjectWrapper<?> parentWrapper,
                                           DataObjectWrapper<?> elementWrapper,
                                           DataObjectCollection collectionMetadata)

Performs bi-directional collection linking, ensuring that for bi-directional collection relationships that both sides of the relationship are properly populated.

Parameters:

collectionMetadata - collection

elementWrapper - element

parentWrapper - parent

isPrimaryKeyModified

protected boolean isPrimaryKeyModified(DataObjectMetadata metadata,
                                       Set<String> modifiedPropertyPaths)

Checks if primary key can be modified.

Returns:

whether primary key can be modified.

cascadeLinkingAnnotations

protected void cascadeLinkingAnnotations(DataObjectWrapper<?> wrapped,
                                         Map<String,Set<String>> decomposedPaths,
                                         Set<Object> linked)

Gets indexes that have been modified.

Returns a list of cascade links in the field names that are also in the decomposed paths.

Parameters:

decomposedPaths - contains field names to be used.

linked -

wrapped - used to get all field names.

assembleLinkingPaths

protected List<String> assembleLinkingPaths(Link link)

Returns a list of link paths based on provided link.

Parameters:

link - used get paths from.

Returns:

list of paths

decomposePropertyPaths

protected Map<String,Set<String>> decomposePropertyPaths(Set<String> changedPropertyPaths)

Returns decomposed property paths based on changedPropertyPaths

Parameters:

changedPropertyPaths - changes to property paths

Returns:

map decomposed property paths with changedPropertyPaths

decomposePropertyPaths

protected Map<String,Set<String>> decomposePropertyPaths(Set<String> changedPropertyPaths,
                                                         String prefix)

Returns decomposed property paths that start with the provide prefix

Parameters:

changedPropertyPaths - changes to property paths

prefix - filter that paths must start with

Returns:

map decomposed property paths with changedPropertyPaths