Oracle® Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework 11g Release 1 (11.1.1.7.2) Part Number B31974-15 |
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This appendix lists the most commonly used methods in the interfaces and classes of the ADF Business Components layer of Oracle Application Development Framework (Oracle ADF).
This appendix contains the following sections:
Section E.1, "Most Commonly Used Methods in the Client Tier"
Section E.2, "Most Commonly Used Methods in the Business Service Tier"
All of the interfaces described in this section are designed for use by client-layer code and are part of the oracle.jbo.*
package.
This section provides a summary of the most frequently called, written, and overridden methods for the key ADF Business Components interfaces.
Note:
The corresponding implementation classes for these oracle.jbo.*
interfaces are intentionally designed to not be directly accessed by client code. Section E.2, "Most Commonly Used Methods in the Business Service Tier" shows that the implementation classes reside in the oracle.jbo.server.*
package and generally have the suffix Impl
in their name to help remind you not to use them in your client-layer code.
An application module is a business service component that acts as a transactional container for other ADF components and coordinates with them to implement a number of Java EE design patterns important to business application developers. These design pattern implementations enable your client code to work easily with updatable collections of value objects, based on fast-lane reader SQL queries that retrieve only the data needed by the client, in the way the client wants to view it. Changes made to these value objects are automatically coordinated with your persistent business domain objects in the business service tier to enforce business rules consistently and save changes back to the database. Table E-1 describes the operations that you can perform on an application module using the ApplicationModule
interface.
Note:
For the complete list of design patterns that ADF Business Components implements, see Appendix F, "ADF Business Components Java EE Design Pattern Catalog."
Table E-1 ApplicationModule Interface
If you want to... | Call this ApplicationModule interface method |
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Access an existing view object instance using the assigned instance name (for example, |
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Create a new view object instance from an existing definition |
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Create a new view object instance from a SQL Statement |
Notes: This incurs runtime overhead to describe the "shape" of the dynamic query's |
Access a nested application module instance by name |
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Create a new nested application module instance from an existing definition |
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Find a view object instance in a nested application module using a dot-notated name (for example, |
Notes: You can use this method to find an instance of a view object belonging to a nested application module in a single method call. This way you do not need to first call |
Access the current transaction object |
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In addition to generic application module access, Oracle JDeveloper can generate a custom YourApplicationModuleName
interface containing service-level custom methods that you've chosen to expose to the client. You use the Client Interface page of the Edit Application Module dialog to select the methods that you want to appear in your client interface.
The Transaction
interface exposes methods allowing the client to manage pending changes in the current transaction. Table E-2 describes the operations that you can perform on the transaction using the Transaction
interface.
Table E-2 Transaction Interface
If you want to... | Call this Transaction interface method |
---|---|
Commit pending changes |
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Roll back pending changes |
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Execute a one-time database command or block of PL/SQL |
Notes: Do not use this command with methods that require retrieving |
Validate all pending invalid changes in the transaction |
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Change the default locking mode |
Notes: You can set the locking mode in your configuration by setting the property |
Decide whether to use bundled exception reporting mode or not |
Notes: ADF Controller layer support sets this parameter to |
Decide whether entity caches will be cleared upon a successful commit of the transaction |
Notes: Default is |
Decide whether entity caches will be cleared upon a rollback of the transaction |
Notes: Default is |
Clear the entity cache for a specific entity object |
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A view object is a component that encapsulates a database query and simplifies working with the row set of results it produces. You use view objects to project, filter, join, or sort business data using SQL from one or more tables to cast the data into exactly the format that the user should see on the page or panel. You can create "master-detail" hierarchies of any depth or complexity by connecting view objects together using view links. View objects can produce read-only query results, or when associated with one or more entity objects at design time, can be fully updatable. Updatable view objects can support insertion, modification, and deletion of rows in the result collection, with automatic delegation to the correct business domain objects.
Every view object contains a "default row set" for simplifying the 90 percent of use cases where you work with a single row set of results for the view object's query. A view object implements all the methods on the RowSet
interface by delegating them to this default RowSet
. That means you can invoke any RowSet
methods on any view object as well.
Every view object implements the StructureDef
interface to provide information about the number and types of attributes in a row of its row sets. So you can call StructureDef
methods directly on any view object.
Table E-3 describes the operations that you can perform on a view object using the ViewObject
interface
Table E-3 ViewObject Interface
If you want to... | Call this ViewObject interface method |
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Set an additional runtime |
Notes: This |
Set a dynamic |
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Create a Query-by-Example criteria collection |
Notes: You then create one or more |
Apply a Query-by-Example criteria collection |
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Set a query optimizer hint |
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Access the attribute definitions for the key attributes in the view object |
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Add a dynamic attribute to rows in this view object's row sets |
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Clear all row sets produced by a view object |
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Remove a view object instance and its resources |
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Set an upper limit on the number of rows that the view object will attempt to fetch from the database |
Notes: Default is -1, which means to impose no limit on how many rows would be retrieved from the database if you iterated through them all. By default, as you iterate through them, they are fetched lazily. |
In addition to generic ViewObject
access, JDeveloper can generate you a custom YourViewObjectName
interface containing view object-level custom methods that you've chosen to expose to the client. You use the Client Interface page of the Edit View Object dialog to select the methods that you want to appear in your client interface.
A row set is an object that contains a set of rows, typically produced by executing a view object's query.
Every RowSet
aggregates a "default row set iterator" for simplifying the 90 percent of use cases where you need only a single iterator over the row set. A RowSet
object implements all the methods on the RowSetIterator
interface by delegating them to this default RowSetIterator
. This means you can invoke any RowSetIterator
method on any RowSet
object (or view object, since it implements RowSet
, as well for its default RowSet
).
Table E-4 describes the operations that you can perform on a row set using the RowSet
interface.
Table E-4 RowSet Interface
If you want to... | Call this RowSet interface method |
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Set a |
Notes: Bind variable ordinal positions are zero-based. |
Avoid view object row caching if data is being read only once |
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Force a row set's query to be (re)executed (in the case of exclusive view object instances) or potentially executed (in the case of shared view object instances) |
Notes: The behavior of this method differs depending on whether the view object belongs to a shared application module or not. When reexecuting the query for an exclusive view object (not an instance of a shared module), a new query collection is created. Before executing the query for a shared view object instance, a check is performed to determine whether the results already exist. Already cached results will be reused for the shared view object instance instead of reexecuting the query. If you want to ensure that the results for a shared view object instance are refreshed, you can invoke the |
Estimate the number of rows in a view object's query result |
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Produce an XML document for rows in a view object row set |
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Process all rows from an incoming XML document |
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Set whether a row set will automatically see new rows based on the same entity object created through other row sets |
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Create a secondary iterator to use for programmatic iteration |
Notes: If you plan to find and use the secondary iterator by name later, then pass in a string name as the argument; otherwise, pass |
A row set iterator is an iterator over the rows in a row set. By default it allows you to iterate both forward and backward through the rows. Table E-5 describes the operations that you can perform on a row set using the RowSetIterator
interface.
Table E-5 RowSetIterator Interface
If you want to... | Call this RowSetIterator interface method |
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Get the first row of the iterator's row set |
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Test whether there are more rows to iterate |
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Get the next row of an iterator's row set |
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Find a row in this iterator's row set with a given key value |
Notes: It's important that the |
Create a new row to populate for insertion |
Notes: The new row will already have default values set for attributes which either have a static default value supplied at the entity object or view object level, or if the values have been populated in an overridden |
Create a view row with an initial set of foreign key and/or discriminator attribute values |
Notes: You use this method when working with view objects that can return one of a "family" of entity object subtypes. By passing in the correct discriminator attribute value in the call to create the row, the framework can create you the correct matching entity object subtype underneath. |
Insert a new row into the iterator's row set |
Notes: It's a good habit to always immediately insert a newly created row into the rowset. That way you will avoid a common gotcha of creating the row but forgetting to insert it into the rowset. |
Get the last row of the iterator's row set |
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Get the previous row of the iterator's row set |
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Reset the current row pointer to the slot before the first row |
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Close an iterator when done iterating |
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Set a given row to be the current row |
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Remove the current row |
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Remove the current row to later insert it at a different location in the same iterator |
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Remove the current row from the current collection but do not remove it from the transaction. |
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Set/change the number of rows in the range (a "page" of rows the user can see) |
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Scroll to view the nth page of rows (1-based) |
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Scroll to view the range of rows starting with row number n |
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Set row number n in the range to be the current row |
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Get all rows in the range as a row array |
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A row is generic value object. It contains attributes appropriate in name and Java type for the view object that it is related to. Table E-6 describes the operations that you can perform on a view object row using the Row
interface.
Table E-6 Row Interface
If you want to... | Call this Row interface method |
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Get the value of an attribute by name |
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Set the value of an attribute by name |
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Produce an XML document for a single row |
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Eagerly validate a row |
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Read row attribute values from XML |
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Remove the row |
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Flag a newly created row as temporary (until updated again) |
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Retrieve the attribute structure definition information for a row |
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Get the |
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In addition to generic Row
access, JDeveloper can generate a custom YourViewObjectName
Row
interface containing your type-safe attribute getter and setter methods, as well as any desired row-level custom methods that you've chosen to expose to the client. You use the Client Row Interface page of the Edit View Object dialog to select the methods that you want to appear in your client interface.
The StructureDef
interface provides access to runtime metadata about the structure of a Row
object.
In addition, for convenience every view object implements the StructureDef
interface as well, providing access to metadata about the attributes in the resulting view rows that its query will produce.
Table E-7 describes the operations that you can perform on a view object row using the StructureDef
interface.
Table E-7 StructureDef Interface
If you want to... | Call this StructureDef interface method |
---|---|
Access attribute definitions for all attributes in the view object row |
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Find an attribute definition by name |
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Get attribute definition by index |
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Get number of attributes in a row |
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The AttributeDef
interface provides attribute definition information for any attribute of a view object row or entity object instance like attribute name, Java type, and SQL type. It also provides access to custom attribute-specific metadata properties that can be inspected by generic code you write, as well as UI hints that can assist in rendering an appropriate user interface display for the attribute and its value. Table E-8 describes the operations that you can perform on an attribute using the AttributeDef
interface.
Table E-8 AttributeDef Interface
If you want to... | Call this AttributeDef interface method |
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Get the Java type of the attribute |
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Get the SQL type of the attribute |
Notes: The |
Determine the kind of attribute |
Notes: A simple attribute is one that returns one of the constants |
Get the Java type of elements contained in an |
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Get the SQL type of elements contained in an |
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Get the name of the attribute |
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Get the index position of the attribute |
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Get the precision of a numeric attribute or the maximum length of a string attribute |
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Get the scale of a numeric attribute |
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Get the underlying column name corresponding to the attribute |
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Get attribute-specific custom property values |
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Get the UI |
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Test whether the attribute is mandatory |
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Test whether the attribute is queriable |
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Test whether the attribute is part of the primary key for the row |
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The AttributeHints
interface exposes UI hint information that you can use to render an appropriate user interface display for the attribute and its value. Table E-9 describes the operations that you can perform on an attribute using the AttributeHints
interface.
Table E-9 AttributeHints Interface
If you want to... | Call this AttributeHints interface method |
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Get the UI label for the attribute |
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Get the tooltip for the attribute |
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Get the formatted value of the attribute, using any format mask supplied |
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Get the display hint for the attribute |
Notes: The display hint will have a string value of either |
Get the preferred control type for the attribute |
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Parse a formatted string value using any format mask supplied for the attribute |
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The implementation classes corresponding to the oracle.jbo.*
interfaces, as described in Section E.1, "Most Commonly Used Methods in the Client Tier," are intentionally designed to not be directly accessed by client code. They reside in a different package named oracle.jbo.server.*
and have the Impl
suffix in their name to help remind you not to use them in your client-layer code.
In your business service tier implementation code, you can use any of the same methods that are available to clients, but in addition you can also:
Safely cast any oracle.jbo.*
interface to its oracle.jbo.server.*
package implementation class and use any methods on that Impl
class as well.
Override any of the public
or protected
methods for the base framework implementation classes and write custom code in your component subclass before or after calling super.
methodName
()
to augment or change the default functionality.
This section provides a summary of the most frequently called, written, and overridden methods for the key ADF Business Components classes.
Before examining the specifics of individual classes, it's important to understand how you can control which custom Java files each of your components will use. When you don't need a customized subclass for a given component, you can just let the base framework class handle the implementation at runtime.
Each business component you create comprises a single XML component descriptor, and zero or more related custom Java implementation files. Each component that supports Java customization has a Java page in its component overview editor in the JDeveloper IDE. By selecting or deselecting the different Java classes, you control which ones will be created for your component. If none of the classes is specified, then your component will be an XML-only component, which simply uses the base framework class as its Java implementation. Otherwise, tick the checkbox of the related Java classes for the current component that you need to customize. JDeveloper will create a custom subclass of the framework base class in which you can add your code.
Note:
You can set up global IDE preferences for the Java classes to be generated by default for each ADF business component type by choosing Tools > Preferences > Business Components and ticking the checkboxes to indicate what you want your defaults to be.
A best practice is to always generate entity object and view row classes, even if you don't require any custom code in them other than the automatically generated getter and setter methods. These getter and setter methods offer you compile-time type checking that prevents errors surfacing at runtime in response to an attribute having been set to an incorrect kind of value.
The ApplicationModuleImpl
class is the base class for application module components. Since the application module is the ADF component used to implement a business service, think of the application module class as the place where you can write your service-level application logic. The application module coordinates with view object instances to support updatable collections of value objects that are automatically "wired" to business domain objects. The business domain objects are implemented as ADF entity objects.
Table E-10 describes the operations that you can perform on an application module using the ApplicationModuleImpl
class.
Table E-10 Methods You Typically Call on ApplicationModuleImpl
If you want to... | Call this method of the ApplicationModuleImpl class |
---|---|
Perform any of the common application module operations from inside your class, which can also be done from the client |
For a list of these methods, see Section E.1.1, "ApplicationModule Interface." |
Access a view object instance that you added to the application module's data model at design time |
Notes: JDeveloper generates this type-safe view object instance getter method for you to reflect each view object instance in the application module's design time data model. |
Access the current |
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Access a nested application module instance that you added to the application module at design time |
Notes: JDeveloper generates this type-safe application module instance getter method for you to reflect each nested application module instance added to the current application module at design time. |
Table E-11 describes the operations that you can perform on an application module using your custom ApplicationModuleImpl
class.
Table E-11 Methods You Typically Write in Your Custom ApplicationModuleImpl Subclass
If you want to... | Write a method like this in your custom ApplicationModuleImpl class |
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Invoke a database stored procedure |
Notes: Use the appropriate method on the For sample code that demonstrates encapsulating a call to a PL/SQL stored procedure inside your application module, see Section 37.4, "Invoking Stored Procedures and Functions." |
Expose custom business service methods on your application module |
Notes: Select the method name on the Client Interface page of the Edit Application Module dialog to expose it for client access if required. |
JDeveloper can generate a custom YourApplicationModuleName
interface containing service-level custom methods that you've chosen to expose to the client. You can use the Client Interface page of the Edit Application Module dialog to select the methods that you want to appear in your client interface.
Table E-12 describes the operations that you can override on an application module using your custom ApplicationModuleImpl
class.
Table E-12 Methods You Typically Override in Your Custom ApplicationModuleImpl Subclass
If you want to... | Override this method in your custom ApplicationModuleImpl class |
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Perform custom setup code the first time an application module is created and each subsequent time it gets used by a different client session. |
Notes: This is the method you'd use to set up per-client context info for the current user in order to use Oracle's Virtual Private Database (VPD) features. It can also be used to set other kinds of PL/SQL package global variables, whose values might be client-specific, on which other stored procedures might rely. This method is also useful to perform setup code that is specific to a given view object instance in the application module. If instead of the view object setup code being instance-specific, you want it to be initialized for every instance ever created of that view object component, then put the setup logic in an overridden |
Perform custom setup code after the application module's transaction is associated with a database connection from the connection pool |
Notes: Can be a useful place to write a line of code that uses For details about the TKPROF utility, see the "Understanding SQL Trace and TKPROF" section in the Oracle Database Performance Tuning Guide. |
Perform custom setup code before the application module's transaction releases its database connection back to the database connection pool |
Notes: If you have set |
Write custom application module state to the state management XML snapshot |
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Read and restore custom application module state from the state management XML snapshot |
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The DBTransactionImpl2
class — which extends the base DBTransactionImpl
class, and is constructed by the DatabaseTransactionFactory
class — is the base class that implements the DBTransaction
interface, representing the unit of pending work in the current transaction.
Table E-13 describes the operations that you can perform on a transaction using the DBTransaction
class.
Table E-13 Methods You Typically Call on DBTransaction
If you want to... | Call this method on the DBTransaction class |
---|---|
Commit the transaction |
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Roll back the transaction |
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Eagerly validate any pending invalid changes in the transaction |
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Create a JDBC |
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Create a JDBC |
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Create a JDBC |
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Add a warning to the transaction's warning list |
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Table E-14 describes the operations that you can perform on a transaction using your custom DBTransactionImpl2
subclass.
Table E-14 Methods You Typically Override in Your Custom DBTransactionImpl2 Subclass
If you want to... | Override this method in your custom DBTransactionImpl2 class |
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Perform custom code before or after the transaction commit operation |
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Perform custom code before or after the transaction rollback operation |
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In order for your custom DBTransactionImpl2
subclass to be used at runtime, there are you must follow these steps:
Create a custom subclass of DatabaseTransactionFactory
that overrides the create method to return an instance of your custom DBTransactionImpl2
subclass like this:
package com.yourcompany.adfextensions; import oracle.jbo.server.DBTransactionImpl2; import oracle.jbo.server.DatabaseTransactionFactory; import com.yourcompany.adfextensions.CustomDBTransactionImpl; public class CustomDatabaseTransactionFactory extends DatabaseTransactionFactory { /** * Return an instance of our custom CustomDBTransactionImpl class * instead of the default implementation. * * @return An instance of our custom DBTransactionImpl2 implementation. */ public DBTransactionImpl2 create() { return new CustomDBTransactionImpl(); } }
Tell the framework to use your custom transaction factory class by setting the value of the TransactionFactory
configuration property to the fully qualified class name of your custom transaction factory. As with other configuration properties, if not supplied in the configuration XML file, it can be provided alternatively as a Java system parameter of the same name.
The EntityImpl
class is the base class for entity objects, which encapsulate the data, validation rules, and business behavior for your business domain objects.
Table E-15 describes the operations that you can perform on an entity object using the EntityImpl
class.
Table E-15 Methods You Typically Call on EntityImpl
If you want to... | Call this method in the EntityImpl class |
---|---|
Get the value of an attribute |
Notes: This code-generated getter method calls |
Set the value of an attribute |
Notes: This code-generated setter method calls |
Get the value of an attribute by name |
|
Set the value of an attribute by name |
|
Eagerly perform entity object validation |
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Refresh the entity from the database |
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Populate the value of an attribute without marking it as being changed, but sending notification of its being changed so that the UI refreshes the value on the screen/page |
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Access the |
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Get the |
|
Determine the state of the entity instance, irrespective of whether it has already been posted (but not yet committed) in the current transaction |
Notes: This method will return one of the constants |
Determine the state of the entity instance |
Notes: This method is typically relevant only if you are programmatically using the |
Get the value originally read from the database for a given attribute |
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Eagerly lock the database row for an entity instance |
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Table E-16 describes the operations that you can perform on an entity object using your custom EntityImpl
subclass.
Table E-16 Methods You Typically Write in Your Custom EntityImpl Subclass
If you want to... | Write a method like this in your custom EntityImpl subclass |
---|---|
Perform attribute-specific validation |
Notes: Register the attribute validator method by adding a MethodValidator rule on the correct attribute in the Validation page of the Edit Entity Object dialog. |
Perform entity-level validation |
Notes: Register the entity-level validator method by adding a MethodValidator rule on the entity in the Validation panel of the Edit Entity Object dialog. |
Calculate the value of a transient attribute |
Add your calculation code to the generated |
Table E-17 describes the operations that you can override on an entity object using your custom EntityImpl
subclass.
Table E-17 Methods You Typically Override in Your Custom EntityImpl Subclass
If you want to... | Override this method in your EntityImpl subclass |
---|---|
Set calculated default attribute values, including programmatically populating the primary key attribute value of a new entity instance |
Notes: After calling |
Modify attribute values before changes are posted to the database |
|
Augment or change the standard |
Notes: This method checks the value of the operation flag to the constants |
Perform complex, SQL-based validation after all entity instances have been posted to the database but before those changes are committed |
|
Insure that a related, newly-created, parent entity gets posted to the database before the current child entity on which it depends |
Notes: If the parent entity is related to this child entity via a composition association, then the framework already handles posting the changes automatically. If they are only associated (but not composed), then you need to override |
Note:
It is possible to write attribute-level validation code directly inside the appropriate set
AttributeName
method of your EntityImpl
class; however, adopting the MethodValidator
approach suggested in Table E-16 conveniently places all the validations in effect on the Validation Rules page of the overview editor for the attributes of the entity object.
WARNING:
It is also possible to override the validateEntity()
method to write entity-level validation code; however, if you want to maintain the benefits of the ADF bundled exception mode — where the framework collects and reports a maximal set of validation errors back to the client user interface — use the MethodValidator
approach suggested in Table E-16. This allows the framework to automatically collect all of your exceptions that your validation methods throw without your having to understand the bundled exception implementation mechanism. Overriding the validateEntity()
method directly shifts the responsibility onto your own code to correctly catch and bundle the exceptions that Oracle ADF would have caught by default, which is non-trivial and a chore to remember and hand-code each time.
The EntityDefImpl
class is a singleton, shared metadata object for all entity objects of a given type in a single Java VM. It defines the structure of the entity instances and provides methods to create new entity instances and find existing instances by their primary key.
Table E-18 describes the operations that you can perform on an entity object using the EntityDefImpl
class.
Table E-18 Methods You Typically Call on EntityDefImpl
If you want to... | Call this method in the EntityDefImpl class |
---|---|
Find an entity object of a given type by its primary key |
Notes: For a tip about getting |
Access the current |
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Find any |
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Retrieve the value of an entity object's custom property |
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Set the value of an entity object's custom property |
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Create a new instance of an entity object |
Notes: Alternatively, you can expose custom |
Iterate over the entity instances in the cache of this entity type |
|
Access an array list of entity definition objects for entities that extend the current one. |
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Table E-19 describes the operations that you can perform on an entity object using your custom EntityDefImpl
class.
Table E-19 Methods You Typically Write on EntityDefImpl
If you want to... | Write a method like this in your custom EntityDefImpl class |
---|---|
Allow other classes to create an entity instance with an initial type-safe set of attribute values or setup information |
Notes: Internally, using this method would create and populate an instance of a |
Table E-20 describes the operations that you can perform on an entity object using the EntityDefImpl
class.
Table E-20 Methods You Typically Override on EntityDefImpl
If you want to... | Override this method in your custom EntityDefImpl class |
---|---|
Perform custom metadata initialization when this singleton metaobject is loaded |
|
Avoid using the |
Notes: Set this method to return |
Control whether the |
Notes: Defaults to |
Find any |
Notes: Static method. |
Set the value of an entity object's custom property |
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Allow other classes to create a new instance of an entity object without doing so implicitly via a view object |
Notes: If you don't write a custom create method as noted in Section E.2.5.2, "Methods You Typically Write in Your Custom EntityDefImpl Class", you'll need to override this method and widen the visibility from |
The ViewObjectImpl
class is the base class for view objects.
Table E-21 describes the operations that you can perform on a view object using the ViewObjectImpl
class.
Table E-21 Methods You Typically Call on ViewObjectImpl
If you want to... | Call this method in the ViewObjectImpl class |
---|---|
Perform any of the common view object, row set, or row set iterator operations from inside your class, which can also be done from the client |
For more information about operations at the view object, row set, or row set iterator-level, see Section E.1.3, "ViewObject Interface," Section E.1.4, "RowSet Interface," and Section E.1.5, "RowSetIterator Interface." |
Set an additional runtime |
|
Define a named bind parameter |
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Remove a named bind parameter |
|
Set bind variable values on the default row set by name |
Notes: Only works when you have formally defined named bind variables on your view object. |
Set bind variable values on the default row set |
Notes: Use this method for view objects with binding style of "Oracle Positional" or "JDBC Positional" when you have not formally defined named bind variables. |
Retrieve a subset of rows in a view object's row set based on evaluating an in-memory filter expression |
|
Retrieve a subset of rows in the current range of a view object's row set based on evaluating an in-memory filter expression |
|
Set the number of rows that will be fetched from the database per roundtrip for this view object |
Notes: The default fetch size is a single row at a time. This is definitely not optimal if your view object intends to retrieve many rows, so you should either set the fetch size higher at design time on the Tuning page of the Edit View Object dialog, or set it at runtime using this method. |
Force a row set's query to be (re)executed specifically on a lookup view object instance in a shared application module |
Notes: Reexecuting the query forces a new query collection and will prevent the application module cache from being used. You should only use this method when you are sure that you are accessing the shared application module during setup and not during runtime. This method when used during normal runtime may have unintended side-effects that disrupt the navigation of users accessing the collection concurrently. If you want to refresh the collection from the cache without creating a new query collection, call |
Table E-22 describes the operations that you can perform on a view object using your custom ViewObjectImpl
subclass.
Table E-22 Methods You Typically Write in Your Custom ViewObjectImpl Subclass
If you want to... | Write a method like this in your custom ViewObjectImpl subclass |
---|---|
Provide clients with type-safe methods to set bind variable values without exposing positional details of the bind variables themselves |
Notes: Internally, this method would call the |
JDeveloper can generate a custom YourViewObjectName
interface containing view object custom methods that you've chosen to expose to the client. You can use the Client Interface page of the Edit View Object to select the methods that you want to appear in your client interface.
Table E-23 describes the operations that you can perform on a view object using your custom ViewObjectImpl
subclass.
Table E-23 Methods You Typically Override in Your Custom ViewObjectImpl Subclass
If you want to... | Override this method in your custom ViewObjectImpl subclass |
---|---|
Initialize custom view object class members (not row attributes) when the view object instance is created for the first time |
Notes: This method is useful to perform set up logic that is applicable to every instance of a view object that will ever get created, in the context of any application module. If instead of generic view object setup logic, you need to perform logic specific to a given view object instance in an application module, then override the |
Write custom view object instance state to the state management XML snapshot |
|
Read and restore custom view object instance state from the state management XML snapshot |
|
Customize the execution of the view object query to utilize an alternative data source |
Notes: By default view objects read their data from the database and automate the task of working with the JDBC layer to process the database result sets. However, by overriding appropriate methods in its custom Java class, you can create a view object that programmatically retrieves data from alterative data sources, as described in Section 39.8, "Using Programmatic View Objects for Alternative Data Sources." |
Customize the programmatic view object to utilize an alternative data source and determine whether the query collection has more rows to fetch from the query execution |
|
Customize the programmatic view object to utilize an alternative data source and populate each row of the retrieved data |
|
Customize the programmatic view object to utilize an alternative data source and return a count of the number of rows that will be retrieved |
|
Customize the programmatic view object to utilize an alternative data source and release any resources that may be associated with a row set that is being closed |
|
Change or augment the way that the |
|
The ViewRowImpl
class is the base class for view row objects.
Table E-24 describes the operations that you can perform on a view object row using your custom ViewRowImpl
class.
Table E-24 Methods You Typically Call on ViewRowImpl
If you want to... | Call this method in your custom ViewRowImpl class |
---|---|
Perform any of the common view row operations from inside your class, which can also be done from the client |
For more information about the row-level operations, see Section E.1.6, "Row Interface." |
Get the value of an attribute |
|
Set the value of an attribute |
|
Access the underlying entity instance to which this view row is delegating attribute storage |
Notes: You can change the name of the entity usage alias name on the Entity Objects page of the Edit View Object dialog. |
Table E-25 describes the operations that you can perform on a view object row using your custom ViewRowImpl
class.
Table E-25 Methods You Typically Write on ViewRowImpl
If you want to... | Write a method like this in your custom ViewRowImpl class |
---|---|
Calculate the value of a view object-level transient attribute |
Notes: JDeveloper generates the skeleton of the method for you, but you need to write the custom calculation logic inside the method body. |
Perform custom processing of the setting of a view row attribute |
Notes: JDeveloper generates the skeleton of the method for you, but you need to write the custom logic inside the method body if required. |
Determine the updateability of an attribute in a conditional way |
|
Expose logical operations on the current row, optionally callable by clients |
Notes: Often these view-row-level custom methods simply turn around and delegate to a method call on the underlying entity object related to the current row. |
JDeveloper can generate a custom YourViewObjectName
Row
interface containing view row custom methods that you've chosen to expose to the client. You can use the Client Row Interface page of the Edit View Object dialog to select the methods that you want to appear in your client interface.
Table E-26 describes the operations that you can perform on a view object row using your custom ViewRowImpl
subclass.
Before you begin to develop application-specific business components, you can create a layer of classes that extend all of the ADF Business Components framework base implementation classes described in this appendix. An example of a customized framework base class for application module components might look like this:
package com.yourcompany.adfextensions; import oracle.jbo.server.ApplicationModuleImpl; public class CustomApplicationModuleImpl extends ApplicationModuleImpl { /* * We might not yet have any custom code to put here yet, but * the first time we need to add a generic feature that all of * our company's application modules need, we will be very happy * that we thought ahead to leave ourselves a convenient place * in our class hierarchy to add it so that all of the application * modules we have created will instantly benefit by that new feature, * behavior change, or even perhaps, bug workaround. */ }
A common set of customized framework base classes in a package name of your own choosing like com.yourcompany.adfextensions
, each importing the oracle.jbo.server.*
package, would consist of the following classes:
public class CustomEntityImpl extends EntityImpl
public class CustomEntityDefImpl extends EntityDefImpl
public class CustomViewObjectImpl extends ViewObjectImpl
public class CustomViewRowImpl extends ViewRowImpl
public class CustomApplicationModuleImpl extends ApplicationModuleImpl
public class CustomDBTransactionImpl extends DBTransactionImpl2
public class CustomDatabaseTransactionFactory extends DatabaseTransactionFactory
For completeness, you may also want to create customized framework classes for the following classes as well:
public class CustomViewDefImpl extends ViewDefImpl
public class CustomEntityCache extends EntityCache
public class CustomApplicationModuleDefImpl extends ApplicationModuleDefImpl
Overriding anything in these classes would be a fairly rare requirement.