ARRAY TO LIST

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4D v16.3

ARRAY TO LIST


ARRAY TO LIST ( array ; list {; itemRefs} )

Parameter	Type	Description
array	Array	Array from which to copy array elements
list	String, ListRef	Name or reference of list into which to copy array elements
itemRefs	Array	Numeric array of item reference numbers

Description

The ARRAY TO LIST command creates or replaces the hierarchical list or the choice list (created in the List editor) that is specified in list using the elements of the array array.

In the list parameter, you can either pass a choice list (string) or a hierarchical list reference (ListRef). In the latter case, this list must have already been created previously (for example using the New list command) in order for this command to work.

The optional itemRefs parameter, if specified, must be a numeric array synchronized with the array array. Each element, then, indicates the list item reference number for the corresponding element in array. If you omit this parameter, 4D automatically sets the list item reference numbers to 1, 2... N.

Compatibility Note: The ARRAY TO LIST command must be used with caution because of the following limitations:

This command only lets you set first-level items of the list.
When you use this command with a choice list, it modifies the structure of the application (lists are saved in the structure file), so any modifications made locally are lost when the structure file is updated in production.
This command cannot be used in a component with a choice list because they are loaded with their structure as read only.

You can use ARRAY TO LIST to build a list based on the elements of an array. However, to free yourself from these restrictions and make full use of the lists of values, we recommend using the commands of the Hierarchical Lists theme.

Example

The following example copies the array atRegions to the list called “Regions:”

ARRAY TO LIST(atRegions;"Regions")

Example

You want to put the distinct values of a field into a list, for example to create a hierarchical pop-up menu. You can write:

 ALL RECORDS([Company])

 DISTINCT VALUES([Company]country;$arrCountries)

 CountryList:=New list

 ARRAY TO LIST($arrCountries;CountryList)

Error management

An error -9957 is generated when ARRAY TO LIST is applied to a list that is currently being edited in the Design environment List Editor. You can catch this error using an ON ERR CALL project method.