FRM055A - List Component Basics Part A
- List components such as combo box and list view are defined visually by creating the list and adding the fields (columns) to the list using drag and drop. Lists have many properties which are used to control the sorting and display of the list.
- The SELECT command is used to create a loop structure to read and process multiple records from a file based on a specified selection criteria. The SELECT command can be used with physical and logical files.
- You will usually need to clear the list (CLR_LIST) before populating it. ADD_ENTRY adds an entry to a list component. It creates a new row, with the current values for all fields which make up the list's columns.
- There are many events and properties for list components. This exercise provides a simple introduction to using list components
- List columns can be can be configured to support sorting at runtime
- You can change the appearance of your application using Visual Styles and Themes.
- A method routine defines a routine with input and output parameters which may be invoked from within this component. If it is defined as Access(*public) it can be invoked by another component.
Tips & Techniques
- Reusable part components are introduced in the Windows Applications with VLF workshop.
- The ability to put invisible (or hidden) columns into any list is an important concept. In this exercise you want the user to see department description in the combo box, but in the program you need to use the department code (xDepartmentCode) as the key field. The need to show the user a description but programmatically interpret their selection from the list as a key is a very common technique.
What You Should Know
- How to define a list component and its columns
- How to use events such as ItemGotSelection
- How data is mapped into and out of list column source fields.
- How to use the RDML commands