com.db4o.config

Interface ObjectField

All Known Implementing Classes:

Config4Field

public interface ObjectField

configuration interface for fields of classes.

Use ObjectClass.objectField(String) to access this setting.

Method Summary

Methods

Modifier and Type	Method and Description
void	cascadeOnActivate(boolean flag) sets cascaded activation behaviour.
void	cascadeOnDelete(boolean flag) sets cascaded delete behaviour.
void	cascadeOnUpdate(boolean flag) sets cascaded update behaviour.
void	indexed(boolean flag) turns indexing on or off.
void	rename(java.lang.String newName) renames a field of a stored class.

Method Detail

cascadeOnActivate

void cascadeOnActivate(boolean flag)

sets cascaded activation behaviour.

Setting cascadeOnActivate to true will result in the activation of the object attribute stored in this field if the parent object is activated.

The default setting is false.

In client-server environment this setting should be used on both client and server.

This setting can be applied to an open object container.

Parameters:

flag - whether activation is to be cascaded to the member object.

See Also:

Why activation?, ObjectClass.cascadeOnActivate(boolean), ObjectContainer.activate(java.lang.Object, int), Using callbacks

cascadeOnDelete

void cascadeOnDelete(boolean flag)

sets cascaded delete behaviour.

Setting cascadeOnDelete to true will result in the deletion of the object attribute stored in this field on the parent object if the parent object is passed to ObjectContainer.delete(java.lang.Object).

Caution !
This setting will also trigger deletion of the old member object, on calls to ObjectContainer.store(Object). An example of the behaviour can be found in ObjectClass.cascadeOnDelete(boolean)

The default setting is false.

In client-server environment this setting should be used on both client and server.

This setting can be applied to an open object container.

Parameters:

flag - whether deletes are to be cascaded to the member object.

See Also:

ObjectClass.cascadeOnDelete(boolean), ObjectContainer.delete(java.lang.Object), Using callbacks

cascadeOnUpdate

void cascadeOnUpdate(boolean flag)

sets cascaded update behaviour.

Setting cascadeOnUpdate to true will result in the update of the object attribute stored in this field if the parent object is passed to ObjectContainer.store(Object).

The default setting is false.

In client-server environment this setting should be used on both client and server.

This setting can be applied to an open object container.

Parameters:

flag - whether updates are to be cascaded to the member object.

See Also:

com.db4o.ObjectContainer#set, ObjectClass.cascadeOnUpdate(boolean), ObjectClass.updateDepth(int), Using callbacks

indexed

void indexed(boolean flag)

turns indexing on or off.

Field indices dramatically improve query performance but they may considerably reduce storage and update performance.
The best benchmark whether or not an index on a field achieves the desired result is the completed application - with a data load that is typical for it's use.

This configuration setting is only checked when the ObjectContainer is opened. If the setting is set to true and an index does not exist, the index will be created. If the setting is set to false and an index does exist the index will be dropped.

In client-server environment this setting should be used on both client and server.

If this setting is applied to an open ObjectContainer it will take an effect on the next time ObjectContainer is opened.

Parameters:

flag - specify true or false to turn indexing on for this field

rename

void rename(java.lang.String newName)

renames a field of a stored class.

Use this method to refactor classes.

In client-server environment this setting should be used on both client and server.

This setting can NOT be applied to an open object container.

Parameters:

newName - the new field name.