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## org.apache.cayenne.map
Class ObjRelationship

    java.lang.Object
      org.apache.cayenne.map.Relationship
          org.apache.cayenne.map.ObjRelationship

All Implemented Interfaces:
  Serializable, CayenneMapEntry, XMLSerializable

    public class ObjRelationship

extends Relationship

Describes an association between two Java classes mapped as source and target ObjEntity. Maps to a path of DbRelationships.

See Also:
  Serialized Form

Field Summary
`protected String` | `collectionType` Stores the type of collection mapped by a to-many relationship.
`protected List<DbRelationship>` | `dbRelationships`
`static String` | `DEFAULT_COLLECTION_TYPE` Denotes a default type of to-many relationship collection which is a Java List.
`protected int` | `deleteRule`
`protected String` | `mapKey` Stores a property name of a target entity used to create a relationship map.
`protected boolean` | `usedForLocking`

Fields inherited from class org.apache.cayenne.map.Relationship
`name, runtime, sourceEntity, targetEntityName, toMany`

Constructor Summary
`ObjRelationship()`
`ObjRelationship(String name)`

Method Summary
`void` | `addDbRelationship(DbRelationship dbRel)` Appends a DbRelationship to the existing list of DbRelationships.
`void` | `clearDbRelationships()`
`ObjRelationship` | `createReverseRelationship()` Creates a complimentary reverse relationship from target entity to the source entity.
`void` | `dbRelationshipDidChange(RelationshipEvent event)` Deprecated. since 3.0 as ObjRelationship no longer reacts to DbRelationship events.
`void` | `encodeAsXML(XMLEncoder encoder)` Prints itself as XML to the provided XMLEncoder.
`ObjRelationship` | `getClientRelationship()` Returns an ObjAttribute stripped of any server-side information, such as DbAttribute mapping.
`String` | `getCollectionType()` Returns the interface of collection mapped by a to-many relationship.
`String` | `getDbRelationshipPath()` Returns a dot-separated path over mapped DbRelationships.
`List<DbRelationship>` | `getDbRelationships()` Returns an immutable list of underlying DbRelationships.
`int` | `getDeleteRule()` Returns the deleteRule.
`String` | `getMapKey()` Returns a property name of a target entity used to create a relationship map.
`String` | `getReverseDbRelationshipPath()` Returns a reversed dbRelationship path.
`ObjRelationship` | `getReverseRelationship()` Returns a "complimentary" ObjRelationship going in the opposite direction.
`String` | `getReverseRelationshipName()` Returns the name of a complimentary relationship going in the opposite direction or null if it doesn't exist.
`Entity` | `getTargetEntity()` Returns a target ObjEntity of this relationship.
`boolean` | `isFlattened()` Returns true if the relationship is a "flattened" relationship.
`boolean` | `isOptional()` Returns a boolean indicating whether the presence of a non-null source key(s) will not guarantee a presence of a target record.
`boolean` | `isReadOnly()` Returns true if the relationship is flattened, but is not of the single case that can have automatic write support.
`boolean` | `isSourceDefiningTargetPrecenseAndType(EntityResolver entityResolver)` Returns true if the relationship is non-optional and target has no subclasses.
`boolean` | `isSourceIndependentFromTargetChange()` Returns a boolean indicating whether modifying a target of such relationship in any way will not change the underlying table row of the source.
`boolean` | `isToDependentEntity()` Returns true if underlying DbRelationships point to dependent entity.
`boolean` | `isToMany()` Returns a boolean value that determines relationship multiplicity.
`boolean` | `isToPK()` Returns true if the underlying DbRelationships point to a at least one of the columns of the target entity.
`boolean` | `isUsedForLocking()` Returns whether this attribute should be used for locking.
`void` | `recalculateReadOnlyValue()` Recalculates a new readonly value based on the underlying DbRelationships.
`void` | `recalculateToManyValue()` Recalculates whether a relationship is toMany or toOne, based on the underlying db relationships.
`void` | `removeDbRelationship(DbRelationship dbRel)` Removes the relationship `dbRel` from the list of relationships.
`void` | `setCollectionType(String collectionType)`
`void` | `setDbRelationshipPath(String relationshipPath)` Sets mapped DbRelationships as a dot-separated path.
`void` | `setDeleteRule(int value)` Sets the delete rule of the relationship.
`void` | `setMapKey(String mapKey)`
`void` | `setUsedForLocking(boolean usedForLocking)` Sets whether this attribute should be used for locking.
`String` | `toString()` Overrides Object.toString() to return informative description.

Methods inherited from class org.apache.cayenne.map.Relationship
`getName, getParent, getSourceEntity, getTargetEntityName, isRuntime, setName, setParent, setRuntime, setSourceEntity, setTargetEntity, setTargetEntityName`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Field Detail

### DEFAULT_COLLECTION_TYPE

    public static final String DEFAULT_COLLECTION_TYPE

  Denotes a default type of to-many relationship collection which is a Java List.

  Since:
    3.0
  See Also:
    Constant Field Values

### deleteRule

    protected int deleteRule

### usedForLocking

    protected boolean usedForLocking

### dbRelationships

    protected List<DbRelationship> dbRelationships

### collectionType

    protected String collectionType

  Stores the type of collection mapped by a to-many relationship. Null for to-one relationships.

  Since:
    3.0

### mapKey

    protected String mapKey

  Stores a property name of a target entity used to create a relationship map. Only has effect if collectionType property is set to "java.util.Map".

  Since:
    3.0

Constructor Detail

### ObjRelationship

    public ObjRelationship()

### ObjRelationship

    public ObjRelationship(String name)

Method Detail

### encodeAsXML

    public void encodeAsXML(XMLEncoder encoder)

  Prints itself as XML to the provided XMLEncoder.

  Since:
    1.1

### getTargetEntity

    public Entity getTargetEntity()

  Returns a target ObjEntity of this relationship. Entity is looked up in the parent DataMap using "targetEntityName".

  Specified by:
    `getTargetEntity` in class `Relationship`

### getReverseRelationshipName

    public String getReverseRelationshipName()

  Returns the name of a complimentary relationship going in the opposite direction or null if it doesn't exist.

  Since:
    1.2

### getReverseRelationship

    public ObjRelationship getReverseRelationship()

  Returns a "complimentary" ObjRelationship going in the opposite direction. Returns null if no such relationship is found.

### createReverseRelationship

    public ObjRelationship createReverseRelationship()

  Creates a complimentary reverse relationship from target entity to the source entity. A new relationship is created regardless of whether one already exists. Returned relationship is not attached to the source entity and has no name. Throws a `CayenneRuntimeException` if reverse DbRelationship is not mapped.

  Since:
    3.0

### getDbRelationships

    public List<DbRelationship> getDbRelationships()

  Returns an immutable list of underlying DbRelationships.

### addDbRelationship

    public void addDbRelationship(DbRelationship dbRel)

  Appends a DbRelationship to the existing list of DbRelationships.

### removeDbRelationship

    public void removeDbRelationship(DbRelationship dbRel)

  Removes the relationship `dbRel` from the list of relationships.

### clearDbRelationships

    public void clearDbRelationships()

### isOptional

    public boolean isOptional()

  Returns a boolean indicating whether the presence of a non-null source key(s) will not guarantee a presence of a target record. PK..FK relationships are all optional, but there are other more subtle cases, such as PK..PK, etc.

  Since:
    3.0

### isSourceDefiningTargetPrecenseAndType

    public boolean isSourceDefiningTargetPrecenseAndType(EntityResolver entityResolver)

  Returns true if the relationship is non-optional and target has no subclasses.

  Since:
    3.0

### isSourceIndependentFromTargetChange

    public boolean isSourceIndependentFromTargetChange()

  Returns a boolean indicating whether modifying a target of such relationship in any way will not change the underlying table row of the source.

  Since:
    1.1

### isToDependentEntity

    public boolean isToDependentEntity()

  Returns true if underlying DbRelationships point to dependent entity.

### isToPK

    public boolean isToPK()

  Returns true if the underlying DbRelationships point to a at least one of the columns of the target entity.

  Since:
    1.1

### isFlattened

    public boolean isFlattened()

  Returns true if the relationship is a "flattened" relationship. A relationship is considered "flattened" if it maps to more than one DbRelationship. Such chain of DbRelationships is also called "relationship path". All flattened relationships are at least readable, but only those formed across a many-many join table (with no custom attributes other than foreign keys) can be automatically written.

  Returns:
    flag indicating if the relationship is flattened or not.
  See Also:
    `isReadOnly()`

### isReadOnly

    public boolean isReadOnly()

  Returns true if the relationship is flattened, but is not of the single case that can have automatic write support. Otherwise, it returns false.

  Returns:
    flag indicating if the relationship is read only or not

### isToMany

    public boolean isToMany()

  Description copied from class: `Relationship`
  Returns a boolean value that determines relationship multiplicity. This defines semantics of the connection between two nodes described by the source and target entities. E.g. to-many relationship between two Persistent object classes means that a source object would have a collection of target objects. This is a read-only property.

  Overrides:
    `isToMany` in class `Relationship`

### getDeleteRule

    public int getDeleteRule()

  Returns the deleteRule. The delete rule is a constant from the DeleteRule class, and specifies what should happen to the destination object when the source object is deleted.

  Returns:
    int a constant from DeleteRule
  See Also:
    `setDeleteRule(int)`

### setDeleteRule

    public void setDeleteRule(int value)

  Sets the delete rule of the relationship.

  Parameters:
    `value` - New delete rule. Must be one of the constants defined in DeleteRule class.
  Throws:
    `IllegalArgumentException` - if the value is not a valid delete rule.
  See Also:
    `DeleteRule`

### dbRelationshipDidChange

    @Deprecated
    public void dbRelationshipDidChange(RelationshipEvent event)

  Deprecated. since 3.0 as ObjRelationship no longer reacts to DbRelationship events.

### isUsedForLocking

    public boolean isUsedForLocking()

  Returns whether this attribute should be used for locking.

  Since:
    1.1

### setUsedForLocking

    public void setUsedForLocking(boolean usedForLocking)

  Sets whether this attribute should be used for locking.

  Since:
    1.1

### getDbRelationshipPath

    public String getDbRelationshipPath()

  Returns a dot-separated path over mapped DbRelationships.

  Since:
    1.1

### getReverseDbRelationshipPath

    public String getReverseDbRelationshipPath()
                                        throws ExpressionException

  Returns a reversed dbRelationship path.

  Throws:
    `ExpressionException`
  Since:
    1.2

### setDbRelationshipPath

    public void setDbRelationshipPath(String relationshipPath)

  Sets mapped DbRelationships as a dot-separated path.

### recalculateToManyValue

    public void recalculateToManyValue()

  Recalculates whether a relationship is toMany or toOne, based on the underlying db relationships.

### recalculateReadOnlyValue

    public void recalculateReadOnlyValue()

  Recalculates a new readonly value based on the underlying DbRelationships.

### toString

    public String toString()

  Description copied from class: `Relationship`
  Overrides Object.toString() to return informative description.

  Overrides:
    `toString` in class `Relationship`

### getClientRelationship

    public ObjRelationship getClientRelationship()

  Returns an ObjAttribute stripped of any server-side information, such as DbAttribute mapping.

  Since:
    1.2

### getCollectionType

    public String getCollectionType()

  Returns the interface of collection mapped by a to-many relationship. Returns null for to-one relationships. Default for to-many is "java.util.List". Other possible values are "java.util.Set", "java.util.Collection", "java.util.Map".

  Since:
    3.0

### setCollectionType

    public void setCollectionType(String collectionType)

  Since:
    3.0

### getMapKey

    public String getMapKey()

  Returns a property name of a target entity used to create a relationship map. Only has effect if collectionType property is set to "java.util.Map".

  Returns:
    The attribute name used for the map key or `null` if the default (PK) is used as the map key.
  Since:
    3.0

### setMapKey

    public void setMapKey(String mapKey)

  Since:
    3.0

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