A Oracle Forms Generation Capabilities and Workarounds

Alerts

Alert messages are not generated. However, you can store an alert message as a text message in Shared Components in Oracle Application Express application. Text messages can be used to build translatable text strings with substitution variables that can be called from PL/SQL packages, procedures, and functions. See "Working with Shared Components" in Oracle Application Express Application Builder User's Guide.

Blocks

A single block can be mapped to a region in Oracle Application Express. Based upon the block type and data source type (that is, table or view) identified in the Forms XML file, some default mappings are defined. For example, a report block based upon an Oracle view, is mapped to an Interactive report in Oracle Application Express. A form block based upon a table, is mapped to an Interactive report and form in Oracle Application Express. For more information see "Block to Page Region Mappings".

Canvases

In Oracle Forms, the canvas is the object on which the graphical user interface (GUI) is drawn, or the background of the form. In Oracle Application Express, the Application Express engine constructs the appearance of each page in an application using templates. Templates define how pages, page controls, and page components display. Canvases are ignored when generating pages for an Oracle Application Express application.

Coordinates

Depending on the coordinate system used in an Oracle Forms application, coordinates can be expressed in real units such as inches, centimeters, and pixels. The coordinate values cannot be automatically applied to the generated application. One unit in an Oracle Application Express item width might not be equal to one physical pixel in an Oracle Forms application. While Oracle Forms enables specific placement of individual fields by specifying coordinates, Oracle Application Express uses standard HTML tables and all items are positioned relative to other elements and columns within the HTML table.

Editors

In Oracle Forms, editors provide standard editing features, including search and replace and cut, copy, and paste for text items. For a selected text item, an editor is mapped to a HTML editor in Oracle Application Express.

List of Values

A list of values (LOV) can be mapped to an equivalent list of values in Oracle Application Express. When LOVs are selected for inclusion in the conversion to Oracle Application Express their associated record group is included in the conversion. For more information, see the "List of Values Implementation".

Program Units

In the post-generation phase of the Forms Conversion process, program units can be incorporated into your Oracle Application Express application as a PL/SQL package, page process, computation or validation. For more information, see "Implementing Business Logic".

Property Classes

In Oracle Forms, a property class is a named object that contains a list of properties and their settings. An object based on a property class can inherit the settings of any property in that class. Similarly, in Oracle Application Express, a theme is a named collection of templates used to define the user interface of an application. Oracle Application Express has a repository of 20 themes, and you can also create your own custom themes. Property classes are not used within the generation of Oracle Application Express applications.

Record Groups

In Oracle Forms, LOV values are derived from a record group. When a record group is defined, it is associated with a SQL query. When a LOV is generated in Oracle Application Express, the associated record group is used to determine the SQL Query for that LOV. For more information, see "List of Values Implementation".

Triggers

An Oracle Forms trigger is an event-handler written in PL/SQL to augment the default processing behavior. The trigger logic can be incorporated into an Oracle Application Express application as a computation, validation, or PL/SQL process in the post-generation phase. Where feasible, POST-QUERY block trigger logic is automatically incorporated in the generated Oracle Application Express application, as part of the Enhanced Query generation. For more information refer to "Implementing Business Logic".

Visual Attributes

Visual attributes are the font, color, and pattern properties that you can set for form and menu objects that appear in an Oracle Forms application's interface. Using the default cascading style sheets (CSS) installed with Oracle Application Express, or by uploading your own CSS files, style can be applied to your Oracle Application Express application. See "Using Custom Cascading Style Sheets" in Oracle Application Express Application Builder User's Guide.

Windows

A window is the container for all visual objects that comprise an Oracle Forms application, including canvases. In Oracle Application Express, a page holds all of the visual objects for an application. Due to the block mapping resulting in multiple pages, the windows are not used in the conversion process.

Primary Key Assumptions

The generation process assumes that the primary key for an Oracle table is non-updatable, maintained using a database trigger, and has a maximum of two parts.

If the primary key is updatable then the generated application must be modified post-generation. You must modify the item attributes for the primary key. By default, these attributes are generated but displayed as hidden and protected. If there is no database trigger defined to automatically fetch the primary key when inserting a record, then the application will fail when attempting to insert a record. To avoid this error either define a database trigger or modify the generated application post-generation to populate the primary key value before processing the record. To populate the primary key value within the application you can use the item default, create a computation, or create a process. If creating a computation or process it is important to include a condition so that execution only occurs when inserting a record (for example, when the primary key item is NULL).

Oracle Application Express does not support cascading multiple part keys where the key for a child is defined as the primary key of the parent with a counter for each child within that parent key. In such cases, you must define a distinct primary key for the child table with an appropriate means of populating the primary key.

Single Record Block

In Oracle Forms a single record block can be used for both querying data and updating the records returned. Within Oracle Application Express, standard updatable regions cannot also be used as query regions. When an Oracle Forms block is defined as being insertable, updatable, and has a primary key, then the generation mapping defines an interactive report with a form. The interactive report enables you to query the records and the generated Edit link provides navigation to an individual record for update or deletion. A Create Record button enables you to insert records.

If not all the conditions are satisfied then only an interactive report is generated for a single record block. Therefore, only an interactive report is generated and not the corresponding form if one of the following conditions exist:

• the number of records displayed is greater than one

• INSERT allowed is set to false

• UPDATE allowed is set to false

• there is no primary key defined for the underlying table

• the block is based on a view

The interactive report uses the original query, enhanced query, or custom query defined within the project for the block. However, the form is based only on the underlying table. Items characteristics such as radio groups, check boxes, date pickers, editors and list of values will be generated where possible.

Tabular Form

A tabular form defined in Oracle Forms is generated as a tabular form in Oracle Application Expresss providing the number of records displayed is greater than one. Implementing item characteristics, such as select lists, needs to be performed manually post-generation. Non-database items specified in Oracle Forms are not be generated into the tabular form generated by Oracle Application Express, even if they have been included. Implementing non-database items in a tabular form needs to be performed manually post-generation. For more information, see "How to Create a Tabular Form" in Oracle Application Express Advanced Tutorials.

Currently adding validations and non-database items on a tabular form is non-declarative and is covered in the Oracle Application Express Advanced Workshop course. An alternative is to manually create a report and form to replace the tabular form post-generation where it is much easier to add validations and add items without a source of database.

Master Detail Blocks

Within Oracle Forms, master detail forms are defined using block relations. There are several additional criteria that must be examined in order to determine what will be generated for an Oracle Forms master detail relationship. The master block is generated as one of the following:

• An interactive report and a master-detail form

• An interactive report and a form only

• Only an interactive report

The detail blocks are generated independently as either a single record block or a tabular form based on the mappings provided.

An interactive report and master-detail form is only be generated if all the following criteria are satisfied:

• The master and detail blocks are both based on tables, but not the same table, and both have primary keys.

• There is only one detail block.

• There is a valid foreign key relationship between the master and detail blocks.

• The block relations are correctly defined with the Oracle Forms file.

When a master detail form is generated, the detail page is also created within Oracle Application Express. You can manually remove the detail page when reviewing the pages to be generated prior to creating the Oracle Application Express application, or you can delete it manually post-generation.

Alternatively, if both the master and the single detail block are based on the same table and that table has a primary key, then two interactive reports and forms are generated for each block. It is recommended that you manually modify one of the resulting forms post-generation to combine the functionality into a single form and delete the second interactive report and form. However, if the table does not have a primary key or is based on a view then only reports are generated.

Oracle Application Express cannot include more than one tabular form on a page. Therefore, when a file with a master and multiple detail blocks is loaded, the relations are ignored and the master block and each detail block are treated independently as either a single record block or a tabular form based on each blocks properties.

If there is no valid foreign key relationship and the table has a primary key, then the master block is generated as an interactive report and form. Otherwise, it is generated as an interactive report.

Non-Database Block

If a block is not associated with a database table or view then the block is not included for generation. These blocks typically hold menus, navigation bars, and buttons. Given that such components are handled and defined very differently within Oracle Application Express it is not appropriate to generate separate pages for these. However, such blocks can be included if required and will be generated as blank pages.

Processes

Processes are logic controls used to execute data manipulation language (DML) or PL/SQL. A process performs an action at a specified point during the rendering or submission of the page. For example, you can create a process to execute logic or to make a call to the Application Express engine. A process is a unit of logic that runs when a specific event occurs, such as loading or submitting a page. For more information, see "Understanding Page Processes" in Oracle Application Express Application Builder User's Guide.

Processes can be defined as either an application-level process or a page-level process. From a functional perspective, there is no difference between page-level and application-level processes. Application-level processes can be called form any page within the application and may be called On Demand which is especially useful when you have PL/SQL logic that you would like to run from different execution points across multiple pages. Page-level processes can only be called from the page on which they are defined.

Computations

Computations are units of logic used to assign a value to an identified item when a page is submitted or displayed.

Computations can be defined as either an application-level computation or a page-level computation. Most application-level computations are performed for every page in an application. In contrast, computations created at the page-level only execute when that page is rendered or processed. For more information, see "Understanding Page Computations" and "Understanding Application Computation in Oracle Application Express Application Builder User's Guide.

Validations

Validations enable you to create logic controls to verify whether user input is valid. For example, a validation can check whether a value has been entered into a mandatory field. When a validation fails then an error message is displayed and subsequent page processes and computations will not occur. For more information, see "Understanding Validations" in Oracle Application Express Application Builder User's Guide.

There are two distinct types of validations:

• Item-level validations which are specific to a single item.

• Page-level validations which do not apply to any single item, but apply to an entire page.

There are several validation methods:

• SQL - Compares item values to data in the database.

• PL/SQL - Enables you to enter complex logic to validate entered data.

• Item Level Null - Checks if an item's value in session state is NULL.

• Item String Comparison - Compares the value of an item to a specific string.

• Regular Expression - Provides a method to describe text patterns.