Understanding Page Processes

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A page process performs an action at a specified point during the rendering or submission of the page. For example, you can create a page process to execute logic or to make a call to the Application Express engine. A page process is a unit of logic that runs when a specific event occurs, such as loading or submitting a page.

From a functional perspective, there is no difference between page-level and application-level processes. The difference between these two process types is where the process is defined, that is at the page level or at the application level.


See Also:

"Understanding Application Processes"

Topics:

Creating a Page Process

You create a process by running the Create Process Wizard. During the wizard, you define a process name, specify a sequence, the point at which process will execute, and select a process category. You can change nearly all of these attributes on the Edit Page Process page.

To create a new process:

  1. Navigate to the appropriate Page Definition:

    1. Navigate to the Database Home Page.

    2. Click the Application Builder icon.

    3. Select an application.

    4. Select a page.

      The Page Definition appears.

  2. Under Processes, click the Create icon.

  3. Select a category. Table: Process Categories describes available page process categories.

    Process Categories

    Process Category Description

    Data Manipulation

    Data Manipulation process types are frequently used by wizards to support data manipulation language (DML) actions. Application Builder supports the following declarative data manipulation processes:

    • Select Automatic Row Fetch and Automatic Row Processing (DML) to create an automatic data manipulation language (DML) process

    • Use Multi Row Update and Multi Row Delete in conjunction with tabular forms.

    • Use Add Rows to Tabular Form in conjunction with a tabular form

    Close Popup Window

    Upon execution, this process type closes a popup window and refreshes the calling window.

    Form Pagination

    Implements pagination through the detail records associated with a master detail form. Most often used in master detail forms (such as in the Master Detail Wizard), this process checks the master table to determine which set of detail records you are in and determines what the next detail record should be.

    See Also: "Building a Master Detail Form"

    On Demand

    Creates an application-level process that can only be executed when called from a specific page. When you create this process type at the page-level, you are creating reference to an existing application-level process.

    See Also: "About On Demand Application Processes"

    PL/SQL

    Runs the PL/SQL you provide. Use this process type to execute a block of PL/SQL entered directly into the process or to simply call an existing API.

    Reset Pagination

    In Report regions, resets pagination back to the first result set. The Application Express engine keeps track of where the user is within a given result set. This process category returns the user to the beginning result set. In other words, this category resets the counters associated with the report region to return the first part of the result set the next time the result set displays.

    Session State

    Sets the values of existing session state items to null. Select this process type to clear the cache for applications, sessions, or items as well as to clear existing user preferences.

    See Also: "Managing Session State Values" and "Managing User Preferences"

    Web Services

    Implements a Web Service as a process on a page. Running the process submits a request to the service provider.

    See Also: "Invoking a Web Service as a Process"


  4. Follow the on-screen instructions.

Editing Process Attributes

Once you create a process, you can control when the process executes and what the process does by editing attributes on the Edit Page Process page.

To edit an existing page process:

  1. Navigate to the appropriate Page Definition:

    1. Navigate to the Database Home Page.

    2. Click the Application Builder icon.

    3. Select an application.

    4. Select a page.

      The Page Definition appears.

  2. Select the process name.

    The Edit Page Process page appears.

Changing Processing Points and Source

You control when a process executes by specifying a sequence number and a process point under Process Point. You can prevent a process from running during subsequent visits to a page by selecting one of the following options under Run Process:

  • Once for each page visit

  • Once for each session or when reset

Enter the appropriate code for PL/SQL process types. For PL/SQL anonymous block processes, enter the appropriate code under Process. For Clear Cache processes, enter the appropriate code under Source. In the event a process fails, you can optionally define an error message in the Process Error Message field.

Creating Conditional Processes

You can make a process conditional by selecting a condition type and entering an expression under Conditional Processing.

Additionally, you can also make a selection from the When Button Pressed attribute. When you select a button from this list, the process only executes if a user clicks the selected button.

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