Drop Down Lists

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Drop-Down Lists

A control that is a variation of a list box. A drop-down list only displays one item until the user takes an action to display the other objects or choices.

Must be an alphanumeric field with a maximum length of 60.

Any identification is valid.

On NPT's the field will display the same as a normal field, except that the field will be output-only and followed by the drop-down indicator "V", or the character specified in DC@OSVEROP *DROPDOWN=x option. This character is locked-in at compile-time for the best performance when executing.

Drop-Down lists are defined through the DDxx input/output attribute, where xx is AA to 99. The xx defines the drop-down list and links the field to the list data.

Cannot wrap onto another line.

A drop-down list may be removed (or effectively cleared) by the DROP_DD_VALUES Built-In Function described in the Technical Reference Guide.

The list is created and data is added to the drop-down list through the ADD_DD_VALUES Built-In Function described in the Technical Reference Guide.

It is suggested that a site and/or application standard be created for drop-down attributes. The advantages of this is that conflicts are prevented and drop-downs could be loaded in an initialization function then the drop-down attribute could be specified in any function after that. For example the drop-down attribute 'DDST' could be loaded with valid state codes. Then any field that requires a state code to be entered, just requires the 'DDST' attribute to be specified against it for the drop-down list to be active.

A drop-down list exists for the entire life of your LANSA session.

There is a limit of 20 active drop-down lists per LANSA session. More than 20 lists may be added and dropped, but the total number at any one time cannot exceed 20.

There is also a limit on the size of each drop-down list. The maximum size of each drop-down list, including value separators is 6200 characters.

The DROP_DD_VALUES Built-In Function should always be used BEFORE a drop-down list is loaded with its initial data to ensure there is no other data in the list.

The separator character specified should not exist in the data being added or unexpected results will occur.

There are a number of ways of using the ADD_DD_VALUES Built-In Function to load the data into a drop-down list. The following examples illustrate some of the different methods.

One value at a time. Hard-coded values.

DEFINE FIELD(#DROPDATA) TYPE(*CHAR) LENGTH(10)

INPUT_ATR(DDST)

USE BUILTIN(DROP_DD_VALUES) WITH_ARGS(DDCO)