The OraRef interface represents an Oracle REF (reference) as well as a referenceable object (standalone instance).
An Oracle REF is an identifier to a referenceable object. Referenceable objects are stored in rows of an object table. By pinning a REF object, referenceable objects are fetched to the client side. An OraRef object implicitly pins the underlying REF when the attributes of a referenceable object are accessed for the first time. The OraRef also encapsulates the functionality for an object navigational operation utilizing the Complex Object Retrieval Capability (COR).
Attributes of a referenceable object represented by the OraRef object are accessed in the same manner as attributes of an value instance represented by the OraObject interface. When pinned, OraRef contains an OraObject interface through the containment mechanism in COM. At run time, the OraRef interface can be typecast to the OraObject interface.
OraRef provides methods for update and delete operations on a referenceable object, independent of the context from which they originated, such as dynasets, parameters, and so on.
An object-level lock should be obtained before modifying the attributes of a referenceable object. This is done though the Edit method of the OraRefobject.
The CreateOraObject method on the OraDatabase object creates a new referenceable object in the database and returns information associated with the OraRef Object. The CreateOraObject and Update methods pair inserts a new referenceable object in the database.
For information about initializing an OraRef object representing a referenceable object in OO4O or executing a member method of a referenceable object, see "Instantiating Oracle LOBs, Objects, and Collections".
Before running the sample code, make sure that you have the necessary data types and tables in the database. See "Schema Objects Used in the OraObject and OraRef Examples" for schema descriptions used in examples of OraObject/OraRef.
The following example pins the attributes of the PERSON referenceable object in the database.
Dim OraSession as OraSession
Dim OraDatabase as OraDatabase
Dim OraDynaset as OraDynaset
Dim Person as OraRef
'Create the OraSession Object.
Set OraSession = CreateObject("OracleInProcServer.XOraSession")
'Create the OraDatabase Object by opening a connection to Oracle.
Set OraDatabase = OraSession.OpenDatabase("ExampleDb", "scott/tiger", 0&)
'create a dynaset object from customers
set OraDynaset = OraDatabase.CreateDynaset("select * from customers", 0&)
'retrieve a aperson column from customers. Here Value property of
' OraField object returns Person OraRef
set Person = OraDynaset.Fields("aperson").Value
'access the attribute of person. This operation pins the Person ref
'value and fetches the Person referenceable object to the client.
msgbox Person.Name
Example: Accessing Attribute Values
The following example accesses the attributes of the PERSON referenceable object in the database.
Dim OraSession as OraSession
Dim OraDatabase as OraDatabase
Dim OraDynaset as OraDynaset
Dim Person as OraRef
Dim Address as OraObject
'Create the OraSession Object.
Set OraSession = CreateObject("OracleInProcServer.XOraSession")
'Create the OraDatabase Object by opening a connection to Oracle.
Set OraDatabase = OraSession.OpenDatabase("ExampleDb", "scott/tiger", 0&)
'create a dynaset object from customers
set OraDynaset = OraDatabase.CreateDynaset("select * from customers", 0&)
'retrieve a aperson column from customers. Here Value property of OraField
'object returns Person OraRef
set Person = OraDynaset.Fields("aperson").Value
'access the attribute by dot notation.
msgbox Person.Name
'access the attribute using '!' notation ( early binding application)
msgbox Person!Name
'access the attribute by index
msgbox Person(1)
'access the attribute by name
msgbox Person("Name")
'access Addr attribute . This returns Address OraObject.
set Address = Person.Addr
Example: Updating Attribute Values
The following example updates the attributes of the PERSON referenceable object in the database.
Dynaset Example
See "Updating Attribute Values: Dynaset Example".
Parameter Example
See "Updating Attribute Values: Parameter Example".
Example: Inserting Referenceable Objects
The following example inserts the new PERSON referenceable object in the database.
Dim OraSession as OraSession
Dim OraDatabase as OraDatabase
Dim Person as OraRef
'Create the OraSession Object.
Set OraSession = CreateObject("OracleInProcServer.XOraSession")
'Create the OraDatabase Object by opening a connection to Oracle.
Set OraDatabase = OraSession.OpenDatabase("ExampleDb", "scott/tiger", 0&)
'CreateOraObject creates a new referenceable object in the PERSON_TAB object
'table and returns associated OraRef
set Person = OraDatabase.CreateOraObject("PERSON","PERSON_TAB")
'modify the attributes of Person
Person.Name = "Eric"
Person.Age = 35
'Update method inserts modified referenceable object in the PERSON_TAB.
Person.Update