Working with Lists
See also:
Any form field in an Ebase form can be associated with
either a dynamic or a static list using the Lists tab of the form field
properties dialog box. Some aspects of behaviour are shared by both types of list,
but there are also significant differences. Both dynamic lists and static lists
are stand alone elements within the Ebase system and, once created, can be
shared by any number of forms.
A dynamic list represents a list of values that are
extracted dynamically from a database at runtime. Examples could include a list
of customer names, or a list of cities, etc. These lists can be linked, e.g. a
list of countries, followed by a list of regions, followed by a list of cities.
As each value is selected, the next list is populated. The database providing
the list values can be any database to which the Ebase system has access. The
list is prepared when the page is prepared for display.
A static list is a list of values stored within the
Ebase repository database. As the name implies, static lists are intended to be
used when the list values do not change very often. Examples might be TITLE
consisting of values Mr, Miss, Mrs, Dr, etc, or CONTACT_CATEGORY consisting of
values Customer, Vendor, Partner, etc. An important aspect of static lists is
that the values can be displayed in any language. The list is prepared when the
first reference to the list is made, and it is cached in memory thereafter.
A list behaves differently depending on
the type of form field with which it is associated. When associated with a
field which can display multiple values, i.e. a selection dropdown list or a
radio button, a list operates in list mode and a list of values is
presented to the user for selection. This is normally what is required.
However, when a list is associated with other types of field, usually a text
entry field, the list operates in validation mode, and will then
validate the data entered by the user against the list. This mode is intended
to be used for large lists where it is not practical to download all the list
values.
When operating in validation mode, the list can be
customised to control its behaviour when a not found condition occurs.
The available options include:
When operating in list mode, the text 'Please Select' or its
equivalent in other languages will appear at the top of each list. This text is
maintained in system text record 21 and can be changed if required. If a list
contains only one value, the default is to show 'Please Select. If you
check the Set Field with Single List Value checkbox on the form field
properties, list tab, then this text will be removed.