Advanced Forms Builder Topics

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Advanced Forms Builder Topics

• Chapter 10

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Objectives

• Learn about form items that display boilerplate
  items, calculated data, and images
• Create forms that allow users to load and display
  image data
• Create form lists that display static data values
• Learn how to configure forms that retrieve and
  manipulate large data sets
• Understand how to control data block
  relationships

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Creating Non-Input Form Items

• Most form items (text items, radio groups, check
  boxes, and so forth) allow users to input and
  change data values
• Forms Builder also supports a number of items
  that display data but do not allow the user to
  change the displayed value

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Creating Non-Input Form Items
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Creating Non-Input Form Items

• Display items display text data that the user
  cannot modify can also display calculated values
  based on form data values
• Boilerplate objects (text and shapes) placed on
  top of other boilerplate objects, appear in the
  order in which you create them

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Creating Non-Input Form Items

• Following data block form displays data from the
  Clearwater Traders INVENTORY database table
• Display items on this form include
• One that shows value for each inventory item,
  calculated as price times quantity on hand
• Summary display item sums values of all retrieved
  items
• Boilerplate rectangle and text label describe and
  emphasize the summary display item

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Creating Non-Input Form Items
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Creating a Form to Load and Display Graphic Images

• Display graphic image on form as static imported
  image, which incorporates image data into form
  design (.fmb) file and compiles it into .fmx
  file, or as a dynamic image, which loads image
  data from workstation file system into form at
  runtime
• Use static imported images to add graphic
  enhancements that stay the same regardless of
  data that currently appears on form

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Creating a Form to Load and Display Graphic Images

• Use dynamic images to display images retrieved
  from database or file system while form is
  running, or to retrieve and display large static
  images that do not appear every time you run form
• To create a form that loads and displays dynamic
  images that the database stores, base form on
  table that contains data field with BLOB data
  type
• To load images into database, create form trigger
  that uses READ_IMAGE_FILE built-in to load the
  image into form image item

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Creating a Form to Load and Display Graphic Images
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Creating the Data Block and Layout

• Use the Data Block and Layout Wizards to create
  the data block and layout for the ITEM table
  fields
• Recall that the ITEM table has a field named
  ITEM_IMAGE that is a BLOB (binary large object)
  data type, and that this field currently contains
  a locator for the BLOB image

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Creating the Data Block and Layout
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Creating Static Lists in Forms

• A list item is a data block item that displays a
  static list from which users can select to
  provide form inputs
• Use a form list item when the user can select
  from a limited number of choices that do not
  change very often
• Use lists instead of radio buttons when there are
  more than five choices or when there is a limited
  amount of space on the form to display radio
  buttons

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Three Types of Static List Items

• Poplist drop-down list that user opens when
  needed. When user opens list, drop-down box
  displays up to 10 items at once
• T-List also called Text List, always displays
  the current selection. It has up and down scroll
  arrows on right edge, and user can use these
  arrows to scroll through list items sequentially
  and select different values
• Combo box Poplist in which user can enter value
  if desired value does not appear in list

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Creating Static Lists in Forms
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Creating Static Lists In Forms
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Creating Static Lists in Forms
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Creating Static Lists in Forms
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Using Forms with Large Data Sets

• Form developers need to estimate the maximum
  number of records that form queries might
  retrieve, and then design their form applications
  to ensure that form performance remains
  satisfactory

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Using Forms with Large Data Sets

• Approaches for improving form data retrieval
  performance include
• creating indexes on search fields
• training users to count query hits
• forcing users to enter search conditions in forms
  that might retrieve large data sets
• configuring LOVs to allow users to filter data

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Improving Form Data Retrieval
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Improving Form Data Retrieval
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Improving Form Data Retrieval
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Improving Form Data Retrieval
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Controlling Data Block Master-Detail Relationships

• In a master-detail form, master block and detail
  block are coordinated
• Master record and detail record are associated by
  a relationship
• coordination-causing event any operation that
  causes current record in master block to change,
• When user performs a coordination-causing event,
  detail block values also change

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Controlling Data Block Master-Detail Relationships
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Controlling Data Block Master-Detail Relationships

• When you use the Data Block Wizard to create a
  form that displays a master-detail relationship
  between two blocks, Forms Builder automatically
• creates a relation object in the master block
• creates several triggers and PL/SQL program units
  that enforce coordination between the form master
  and detail blocks

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Controlling Data Block Master-Detail Relationships

• The relation object specifies properties about
  the relationship
• name of the detail block
• SQL join condition that specifies the
  relationship between the master block and the
  detail block and how the form handles deletions
  of master block records

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Controlling Data Block Master-Detail Relationships
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Relation Triggers and Program Units
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Controlling Data Block Master-Detail Relationships

• Relations Delete Record Behavior property
  specifies how deleting a record in master block
  affects records in detail block
• Possible values
• Non Isolated prevents user from deleting master
  record when associated detail records exist in
  database
• Isolated allows user to delete master record
  when associated detail records exist
• Cascading performs cascading delete form
  deletes the master record, then deletes all
  associated detail records in detail blocks base
  table

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Controlling Data Block Master-Detail Relationships

• A relations Prevent Masterless Operations
  property specifies whether users can query or
  insert detail block records when there is no
  master record in the master block

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Controlling Data Block Master-Detail Relationships

• A relations Deferred and Automatic Query
  properties work together to determine whether the
  detail block records automatically change when
  the user selects a new master record, or if the
  user has to navigate explicitly to the detail
  block and refresh the detail records

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Relation Triggers and Program Units
These program units are called by the
relation-handling triggers or by one another, and
handle the details of the master-detail processing
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Relation Triggers and Program Units
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Changing Relation Properties Dynamically

• User can specify retrieval properties of a
  relation while form is running
• Use the SET_RELATION_PROPERTY built-in, which has
  the following syntax
• SET_RELATION_PROPERTY('relation_name', property,
  value)

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Changing Relation Properties Dynamically
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Changing Relation Properties Dynamically
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Summary

• Creating Non-input form items
• Display items
• Creating forms to load and display graphic images
• Creating the data block and layout
• Creating static lists
• Types of static lists
• Using forms with large data sets
• Improving form data retrieval
• Controlling data block master-detail
  relationships
• Relation triggers and program units
• Changing relation properties dynamically