4.11.1Class DataManager

Base data manager. This is just an abstract class of definitions to be implemented by the real data managers.

Class DataManager( name, location )

Methods
addEntity	Puts an entity in the data manager.
configure	Configure this data manager.
count	Count records from an entity.
create	Create the database.
createDB	Creates the physical underlying DatabaseResource.
createEntity	Creates an entity in the database. Called back by DataManager.create.
delete	Modifies the values of an entity in the database.
entity	Loads an entity definition.
insert	Inserts a new item in the data pool.
query	Query multiple records from an entity.
queryItem	Query an entity -- for a single item.
update	Modifies the values of an entity in the database.

Methods

addEntity

Puts an entity in the data manager.

addEntity( Entity, entity )

Entity

an instance to be added.

configure

Configure this data manager.

configure( vars )

vars	an array of variables to be configured.
Raise	CodeError if the configuration is not coherent with the type of data manager.

The subclasses must override this mehtod.

count

Count records from an entity.

count( entity, view )

entity	The entity to be queried.
view	A field list or DBView eventually filtering this count

The subclasses must override this mehtod.

create

Create the database.

create( cond )

cond	True if the database should be created only if not found (conditional), false to re-create it.

This performs a self.createDB( cond ) call right after loading all the entities, and then invokes create() onthe entities in the right order.

So, the upstream DB manager should be re-implementing the createDB method to create a new empty DB.

createDB

Creates the physical underlying DatabaseResource.

createDB( cond )

cond	if true should create the database only if not alredy existing.

The subclasses must override this mehtod.

createEntity

Creates an entity in the database. Called back by DataManager.create.

createEntity( entity, cond )

entity	The DBEntity to be created in the database.
cond	True to create only if the entity doesn't exist.

delete

Modifies the values of an entity in the database.

delete( entity, data, eid )

entity	The entity to be added.
data	A dictionary of data to be stored.
Return	The new entity ID.

The subclasses must override this mehtod.

entity

Loads an entity definition.

entity( ename )

ename

The name of the entity to be loaded.

insert

Inserts a new item in the data pool.

insert( entity, data )

entity	The entity to be added.
data	A dictionary of data to be stored.
Return	The new entity ID.

The subclasses must override this mehtod.

query

Query multiple records from an entity.

query( entity, view, start, count )

entity	The entity to be queried.
view	A field list or DBView configuring this query (nil for all).
start	Start after N fetched records (nil for 0).
count	Get N records in the returned data (nil for all).
Return	An array of DBRecord entity containing the retreived data.

The view parameter can be an array of field names that should be retrieved from this entity, or a View that will select just part of the elements.

The subclasses must override this mehtod.

queryItem

Query an entity -- for a single item.

queryItem( entity, key_fields, view )

entity	The entity to be queried.
key_fields	The ID of the entity to retreive.
view	A view shaping the fields to be retreived (or nil)
Return	A DBRecord entity containing the retreived data.

The subclasses must override this mehtod.

update

Modifies the values of an entity in the database.

update( entity, data, eid )

entity	The entity to be added.
data	A dictionary of data to be stored.
Return	The new entity ID.

The subclasses must override this mehtod.