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Oracle® HTML DB
Release 2.0 |
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You can include a variety of different types of forms in your applications. You can include forms that enable users to update just a single row in a table or multiple rows at once. Oracle HTML DB includes a number of wizards you can use to create forms automatically, or you can create forms manually.
Topics:
The easiest way to create a form is to use a wizard. For example, the Form on Table or View Wizard creates one item for each column in a table. It also includes the necessary buttons and processes required to insert, update, and delete rows from the table using a primary key. Each region has a defined name and display position; all other attributes are items, buttons, processes, and branches.
To create a form using a wizard:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Click Create Page.
Select Form.
Under Forms, select a type of form page as described in Table 6-4.
Table 6-4 Forms Page Types
| Form Page Type | Description |
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Builds a form based on stored procedure arguments. Use this approach when you have implemented logic or data manipulation language (DML) in a stored procedure or package. |
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Creates a form based on the columns returned by a SQL query such as an EQUIJOIN. |
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Creates a form that enables users to update a single row in a database table. |
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Creates two pages. One page displays a report. Each row provides a link to the second page to enable users to update each record. Note: This wizard does not support tables having more than 127 columns. Selecting more than 127 columns generates an error. |
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Creates a page with items based on a Web service definition. This wizard creates a user input form, a process to call the Web service, and a submit button. See Also: "Creating a Form on a Web Service" |
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Creates a page with items based on a Web service definition. This wizard creates a user input form, a process to call the Web service, a submit button, and displays the results returned in a report. See Also: "Creating an Input Form and Report on a Web Service" |
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Creates a form that displays a master row and multiple detail rows within a single HTML form. With this form, users can query, insert, update, and delete values from two tables or views. See Also: "Building a Master Detail Form" |
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Creates a read-only version of a form. Typically used to provide a confirmation page at the end of a wizard. |
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Creates a form in which users can update multiple rows in a database. See Also: "Creating a Tabular Form" |
Follow the on-screen instructions.
A tabular form enables users to update multiple rows in a table. The Tabular Form Wizard creates a form to perform update, insert, and delete operations on multiple rows in a database table.
To create a tabular form:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Click Create Page.
Select Form.
Select Tabular Form.
The Tabular Form Wizard appears.
On Identify Table/View Owner:
Specify the table or view owner on which you want to base your tabular form.
Select the operations to be performed on the table (for example, Update, Insert and Delete).
On Identify Table/View Name, select a table.
On Identify Columns to Display:
Specify whether or not to use user interface defaults. Select Yes or No.
User interface defaults enable you to assign default user interface properties to a table, column, or view within a specified schema.
Select the columns (updatable and nonupdatable) to include in the form.
You can modify the column order or your SQL query after you create the page.
On Identify Primary Key, select the Primary Key column and a secondary Primary Key column (if applicable).
On Defaults for Primary and Foreign Keys, select a source type for the primary key column. Valid options include:
Existing trigger - Select this option if a trigger is already defined for the table. You can also select this option if you plan on specifying the primary key column source later after completing the form.
Custom PL/SQL function - Select this option if you wish to provide a PL/SQL function to generate returning key value.
Existing sequence - Select this option is you wish to pick the sequence from a list of sequences available in the selected schema.
On Updatable Columns, select which columns should be updatable.
On Identify Page and Region Attributes.
Specify page and region information.
Select a region template.
Select a report template.
On Identify Tab, specify a tab implementation for this page.
On Button Labels, enter the display text to appear for each button.
On Identify Branching, specify the pages to branch to after the user clicks the Submit and Cancel buttons.
Click Finish.
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Note: Do not modify the select list of a SQL statement of a tabular form after it has been generated. Doing so can result in a checksum error when you alter data in the form. |
A master detail form reflects a one-to-many relationship between two tables in a database. Typically, a master detail form displays a master row and multiple detail rows within a single HTML form. With this form, users can insert, update, and delete values from two tables or views.
To create a master detail form:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Click Create Page.
Select Form.
Select Master Detail Form.
The Master Detail Wizard appears.
On Define Master Table:
Select a table or view owner.
Select a table or view name.
Select the columns to display.
On Define Detail Table:
Specify to show only related tables.
Select the table or view owner.
Select the table or view name.
Select the columns to display.
On Define Primary Key, select the primary key column for the master table, and then select the primary key column for the detail table.
On Define Master and Detail, define the relationships between master and detail tables.
Specify the source for the master table and detail table primary key columns.
On Define Master Options, specify whether or not to include master row navigation.
If you include master row navigation, define navigation order columns. If a navigation order column is not defined, the master update form navigates by the primary key column.
On Choose Layout, specify the layout of the master detail pages.
You can include the master detail as a tabular form on the same page, or add the master detail on a separate page.
On Page Attributes, review and edit the master page and detail page information.
On Identify Tabs, specify whether or not to include an optional tab set.
Click Create.
You can also create a form manually by performing the following steps:
Create an HTML region (to serve as a container for your page items)
Create items to display in the region
Create processes and branches
To create a form manually by creating and HTML region:
Navigate to the appropriate Page Definition:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Select a page.
The Page Definition appears.
Create an HTML region:
Under Regions, click the Create icon.
Select the region type HTML.
Follow the on-screen instructions.
Start adding items to the page:
Under Items, click the Create icon.
Follow the on-screen instructions.
Once you create a form, the next step is to process the data a user types by inserting into or updating the underlying database tables or views. There are three ways to process a form:
One common way to implement a form is to manually create an Automatic Row Processing (DML) process. This approach offers three advantages. First, you are not required to provide any SQL coding. Second, Oracle HTML DB performs DML processing for you. Third, this process automatically performs lost update detection. Lost update detection ensures data integrity in applications where data can be accessed concurrently.
To implement this approach you need to:
Add items, define the Item Source Type as Database Column, and specify a case-sensitive column name.
Select the option Always overrides the cache value.
To create an Automatic Row Processing (DML) process:
Navigate to the appropriate Page Definition:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Select a page.
The Page Definition appears.
Under Processes, click the Create icon.
Select the process enter Data Manipulation.
Select the process category Automatic Row Processing (DML).
Specify the following process attributes:
In the Name field, enter a name to identify the process.
In the Sequence field, specify a sequence number.
From the Point list, select the appropriate processing point. In most instances, select Onload - After Header.
From the Type list, select Automated Row Processing (DML).
Follow the on-screen instructions.
In this approach to form handling, you create one or more processes to handle insert, update, and delete actions. Instead of having the HTML DB engine handling everything transparently, you are in complete control.
For example, suppose you have a form with three items:
P1_ID - A hidden item to store the primary key of the currently displayed row in a table.
P1_FIRST_NAME - A text field for user input.
P1_LAST_NAME - A text field for user input.
Assume also there are three buttons labeled Insert, Update, and Delete. Also assume you have a table T that contains the columns id, first_name, and last_name. The table has a trigger that automatically populates the ID column when there is no value supplied.
To process the insertion of a new row, you create a conditional process of type PL/SQL that executes when the user clicks the Insert button. For example:
BEGIN
INSERT INTO T ( first_name, last_name )
VALUES (:P1_FIRST_NAME, :P1_LAST_NAME);
END;
To process the updating of a row, you create another conditional process of type PL/SQL. For example:
BEGIN
UPDATE T
SET first_name = :P1_FIRST_NAME,
last_name = :P1_LAST_NAME
WHERE ID = :P1_ID;
END;
To process the deletion of a row, you create a conditional process that executes when the user clicks the Delete button. For example:
BEGIN
DELETE FROM T
WHERE ID = :P1_ID;
END;
For certain types of applications, it is appropriate to centralize all access to tables in a single or a few PL/SQL packages. If you created a package to handle DML operations, you can call procedures and functions within this package from an After Submit PL/SQL process to process insert, updates, and delete requests.
Oracle HTML DB populates a form on load, or when the HTML DB engine renders the page. You can populate a form in the following ways:
Create a process and define the type as Automated Row Fetch.
Populate the form manually by referencing a hidden session state item.
To create an Automated Row Fetch process:
Navigate to the appropriate Page Definition:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Select a page.
The Page Definition appears.
Under Processes, click Create.
Select the process type Data Manipulation.
Select the process category Automatic Row Fetch.
Specify the following process attributes:
In the Name field, enter a name to identify the process.
In the Sequence field, specify a sequence number.
From the Point list, select the appropriate processing point.
From the Type list, select Automated Row Fetch.
Follow the on-screen instructions.
You can also populate a form manually by referencing a hidden session state item. For example, the following code in an Oracle HTML DB process of type PL/SQL would set the values of ename and sal. The example also demonstrates how to manually populate a form by referencing a hidden session state item named P2_ID.
FOR C1 in (SELECT ename, sal
FROM emp WHERE ID=:P2_ID)
LOOP
:P2_ENAME := C1.ename;
:P2_SAL := C1.sal;
END LOOP;
In this example:
C1 is an implicit cursor.
The value of P2_ID has already been set.
The process point for this process would be set to execute (or fire) on or before Onload - Before Regions.
You can use validations to check data a user enters before processing. Once you create a validation and the associated error message, you can associate it with a specific item. You can choose to have validation error messages display inline (that is, on the page where the validation is performed) or on a separate error page.
Creating an inline error message involves these steps:
Create a new validation and specify error message text.
Associate the validation with a specific item.
To create a new validation:
Navigate to the appropriate Page Definition:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Select a page.
The Page Definition appears.
Under Validations, click the Create icon.
When the Create Validations Wizard appears, follow the on-screen instructions.
Validations Types are divided into two categories:
Item. These validations start with the term Item and provide common checks you may want to perform on the item with which the validation is associated.
Code. These validations require you provide either a piece of PL/SQL code or SQL query that defines the validation logic. Use this type of validation to perform custom validations that require verifying values of more than one item or accessing additional database tables.
Follow the on-screen instructions.
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Note: Validations cannot contain more than 3,950 characters. |
To associate an item with a validation and specify error message text:
Navigate to the appropriate Page Definition:
Navigate to the Workspace home page.
Click the Application Builder icon.
Select an application.
Select a page.
The Page Definition appears.
Under Validations, select the validation item you want to associate.
The attributes page for the validation appears.
Scroll down to Error Message:
In Error message display location, verify the display location.
In Associated Item, select the item you want to associate with this validation.
Click Apply Changes.
Error message display location identifies where a validation error message displays. Validation error messages can display on an error page or inline within the existing page. Inline error messages can display in a notification area (defined as part of the page template) or within the field label.
To create a hard error that stops processes, including any remaining validations, you must display the error on an error page.