In ColdFusion ORM, you need to define an object mapping
to create persistent objects. The object mapping includes details
such as:
The table name for the object's class
The column name that corresponds to each field in the object
The join conditions for related objects
ColdFusion allows you to specify the mapping in CFCs. Such CFCs
are called as persistent CFCs. Each persistent CFC usually maps
to a table in the database. Each property in the CFC usually maps
to a column in the table. Additional properties may be used to define
relationships and other mapping details.
When ColdFusion creates the Hibernate configuration for the application,
these persistent CFCs are used to automatically generate Hibernate
mapping files, which have the extension ".hbmxml". For example,
if ARTISTS.cfc is a persistent CFC, ColdFusion would automatically
generate Artists.hbmxml. Hibernate mapping files contain the mapping
information in XML format that Hibernate defines, to work with ColdFusion
ORM. These Hibernate mapping files can be created manually.
For more information about creating Hibernate mappings manually,
see Advanced mapping.
To use ColdFusion ORM, ColdFusion application must have ormenabled set
to true in the THIS scope of Application.cfc.
To define a persistent CFC, set persistent="true" in
cfcomponent tag. An array of attributes are available in cfcomponent
and cfproperty to specify mapping information.
For details, see Define ORM mapping.
When the application starts, ColdFusion first loads the Hibernate
configuration file if it is specified in the application. The Hibernate
configuration file contains various configuration parameters like
including, dialect, cache settings, and mapping files that are required
for the application. If a configuration file is not specified, ColdFusion
ORM creates the Hibernate configuration using the default settings.
For details about these configuration parameters, see www.hibernate.org/hib_docs/reference/en/html/session-configuration.html.
After loading the Hibernate configuration, all the mapping files
(*.hbmxml) in the application folder and its mapped folders are
loaded and added to the configuration.
ColdFusion then searches for persistent CFCs in the application
folder and its mapped folders. If the hibernate mapping file is
not present for any persistent CFC, ColdFusion generates it. If
mapping information, such as primary key, foreign key, and column
data type is missing in the persistent CFCs, ColdFusion automatically
inspects the database and identifies the mapping.
ColdFusion then checks if DDL needs to be generated. This can
be configured using the dbcreate option in the
ORM settings. Based on the configuration option specified in dbcreate,
tables are created or updated.The Hibernate SessionFactory is then
built and made available to the application as long as the application
is running. The SessionFactory is used to create Hibernate sessions that
manage the persistent object lifecycle.
In ColdFusion, a Hibernate session starts when the first CRUD
method is called and ends when the request ends or when the ORMCloseSession() method is
called.
To improve performance, Hibernate batches all the Create/Update/Delete
operations in the session and runs them when the session is flushed
or only when necessary. Session Flush happens when the request ends
or when the ORMFlush() method is called.
For transactions, a new session is always created at the start
of a transaction and ends at the end of a transaction. Any previous
open sessions are flushed and closed at the start of the transaction.
The Hibernate configuration is created and loaded only when the
application starts. Therefore, any modifications to the mapping
in the persistent CFCs or in the Hibernate mapping files are not
loaded automatically. To load these modifications, you can either
restart the application or call ORMReload().
To restart the application, you can stop the application using ApplicationStop() and
the next request to any page in this application automatically starts
it.
