Package org.apache.cayenne.reflect

## Interface ClassDescriptor

- All Known Implementing Classes:
    `LazyClassDescriptorDecorator`, `PersistentDescriptor`

      public interface ClassDescriptor

  A runtime descriptor of an persistent class.
  Since:
    1.2

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `Object` | `createObject()` | Creates a new instance of a class described by this object.
    `Map<String,​DbEntity>` | `getAdditionalDbEntities()` | Returns information about additional db entities that is used for this ObjEntity (i.e.
    `PropertyDescriptor` | `getDeclaredProperty​(String propertyName)` | Returns a Java Bean property descriptor matching property name or null if no such property is found.
    `Collection<ObjAttribute>` | `getDiscriminatorColumns()` | Returns a collection of ObjAttribute for the described class, its superclasses and subclasses, that participate in inheritance qualifier.
    `ObjEntity` | `getEntity()` | Returns an ObjEntity associated with this descriptor.
    `EntityInheritanceTree` | `getEntityInheritanceTree()` |
    `Expression` | `getEntityQualifier()` | Returns entity qualifier as a Cayenne expression that includes qualifiers for this entity and all subentities.
    `Collection<AttributeProperty>` | `getIdProperties()` | Returns a collection of the properties mapped to id columns.
    `Collection<ArcProperty>` | `getMapArcProperties()` | Returns a collection over the arc properties whose reverse arcs are to-many maps.
    `Class<?>` | `getObjectClass()` | Returns a class mapped by this descriptor.
    `PropertyDescriptor` | `getProperty​(String propertyName)` | Returns a property descriptor matching property name, or null if no such property is found.
    `Collection<DbEntity>` | `getRootDbEntities()` | Returns a collection of DbEntities that are the root tables for this descriptor's ObjEntity.
    `ClassDescriptor` | `getSubclassDescriptor​(Class<?> objectClass)` | Returns the most "specialized" descriptor for a given class.
    `ClassDescriptor` | `getSuperclassDescriptor()` | Returns a descriptor of the mapped superclass or null if the descriptor's entity sits at the top of inheritance hierarchy or no inheritance is mapped.
    `boolean` | `hasSubclasses()` | Returns whether this class has persistent subclasses.
    `void` | `injectValueHolders​(Object object)` | Prepares object properties for access.
    `boolean` | `isFault​(Object object)` | Returns true if an object is not fully resolved.
    `void` | `shallowMerge​(Object from, Object to)` | Merges object properties from one object to another, avoiding traversal of the ArcProperties.
    `boolean` | `visitAllProperties​(PropertyVisitor visitor)` | Passes the visitor to the properties "visit" method for a combination of all properties, including properties declared in this descriptor, its super descriptors, and all subdescriptors.
    `boolean` | `visitDeclaredProperties​(PropertyVisitor visitor)` | Passes the visitor to the properties "visit" method for all properties declared in this descriptor.
    `boolean` | `visitProperties​(PropertyVisitor visitor)` | Passes the visitor to the properties "visit" method for all properties declared in this descriptor and all its super-decsriptors.

- - ### Method Detail

    - #### getEntity

          ObjEntity getEntity()

      Returns an ObjEntity associated with this descriptor.
      Since:
        3.0

    - #### getRootDbEntities

          Collection<DbEntity> getRootDbEntities()

      Returns a collection of DbEntities that are the root tables for this descriptor's ObjEntity. Usually such collection would contain only one entity, however in cases involving subclass horizontal inheritance, it will be more than one, and in cases of abstract entities with no subclasses, the collection will be empty.
      Since:
        3.0

    - #### getAdditionalDbEntities

          Map<String,​DbEntity> getAdditionalDbEntities()

      Returns information about additional db entities that is used for this ObjEntity (i.e. for flattened attributes).

      Keys are full paths for corresponding flattened attributes.

      Returns:
        information about additional db entities
      Since:
        4.1

    - #### getEntityInheritanceTree

          EntityInheritanceTree getEntityInheritanceTree()

      Since:
        3.0

    - #### hasSubclasses

          boolean hasSubclasses()

      Returns whether this class has persistent subclasses.
      Since:
        3.1

    - #### getObjectClass

          Class<?> getObjectClass()

      Returns a class mapped by this descriptor.

    - #### getSuperclassDescriptor

          ClassDescriptor getSuperclassDescriptor()

      Returns a descriptor of the mapped superclass or null if the descriptor's entity sits at the top of inheritance hierarchy or no inheritance is mapped.

    - #### getSubclassDescriptor

          ClassDescriptor getSubclassDescriptor​(Class<?> objectClass)

      Returns the most "specialized" descriptor for a given class. This method assumes that the following is true:

           this.getObjectClass().isAssignableFrom(objectClass)

    - #### createObject

          Object createObject()

      Creates a new instance of a class described by this object.

    - #### injectValueHolders

          void injectValueHolders​(Object object)
                           throws PropertyException

      Prepares object properties for access. This may include injection of value holders into the object and such.
      Throws:
        `PropertyException`

    - #### shallowMerge

          void shallowMerge​(Object from,
                            Object to)
                     throws PropertyException

      Merges object properties from one object to another, avoiding traversal of the ArcProperties.
      Throws:
        `PropertyException`

    - #### getProperty

          PropertyDescriptor getProperty​(String propertyName)

      Returns a property descriptor matching property name, or null if no such property is found. Lookup includes properties from this descriptor and all its superclass descriptors. Returned property can be any one of `AttributeProperty`, `ToManyProperty`, `ToOneProperty`.

    - #### getDeclaredProperty

          PropertyDescriptor getDeclaredProperty​(String propertyName)

      Returns a Java Bean property descriptor matching property name or null if no such property is found. Lookup DOES NOT including properties from the superclass descriptors. Returned property can be any one of `AttributeProperty`, `ToManyProperty`, `ToOneProperty`.

    - #### getIdProperties

          Collection<AttributeProperty> getIdProperties()

      Returns a collection of the properties mapped to id columns.
      Since:
        3.1

    - #### getDiscriminatorColumns

          Collection<ObjAttribute> getDiscriminatorColumns()

      Returns a collection of ObjAttribute for the described class, its superclasses and subclasses, that participate in inheritance qualifier. If a discriminator expression specifies a DbAttribute instead of an ObjAttribute, a synthetic ObjAttribute is created and returned.
      Since:
        3.1

    - #### getEntityQualifier

          Expression getEntityQualifier()

      Returns entity qualifier as a Cayenne expression that includes qualifiers for this entity and all subentities.
      Since:
        3.0

    - #### getMapArcProperties

          Collection<ArcProperty> getMapArcProperties()

      Returns a collection over the arc properties whose reverse arcs are to-many maps. I.e. for each ArcProperty in returned collection, the following is true:

           arc.getComplimentaryReverseArc() instanceof ToManyMapProperty

      Since:
        3.1

    - #### visitProperties

          boolean visitProperties​(PropertyVisitor visitor)

      Passes the visitor to the properties "visit" method for all properties declared in this descriptor and all its super-decsriptors. Properties that are overridden in subdescriptors will include overridden information. Walkthrough is terminated in case one of the properties returns false. Returns true if all visited properties returned true, false - if one property returned false.

    - #### visitDeclaredProperties

          boolean visitDeclaredProperties​(PropertyVisitor visitor)

      Passes the visitor to the properties "visit" method for all properties declared in this descriptor. This property set excludes inherited properties, even those that got overridden in this subclass. Walkthrough is terminated in case one of the properties returns false. Returns true if all visited properties returned true, false - if one property returned false.
      Since:
        3.0

    - #### visitAllProperties

          boolean visitAllProperties​(PropertyVisitor visitor)

      Passes the visitor to the properties "visit" method for a combination of all properties, including properties declared in this descriptor, its super descriptors, and all subdescriptors. Walkthrough is terminated in case one of the properties returns false. Returns true if all visited properties returned true, false - if one property returned false.
      Since:
        3.0

    - #### isFault

          boolean isFault​(Object object)

      Returns true if an object is not fully resolved.