TDBLookupComboBox without ListSource
lazarus / 16-Databases

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thierrybo · 2010-03-24 19:11

Hi,

just to be sure what *should* be the correct behavior. I need a
TDBLookupComboBox
only to retrieve list data. I do not need to update another table. If
I provide ListSource and ListField, I get nothing. I have to enter
manually a dummy field name in KeyField to get the list. This works
with lazarus compiled from latest sources. With  0.9.28-2 the list is
empty and if I provide the dummy keyfield i get an Exception.

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DougNettleton · 2010-03-24 20:43

So, you're asking how a component should work that you want to use for
something other than it's intended purpose?

Maybe you need another component.

From your subject TDBLookupComboBox without ListSource

but you say you only need it to retrieve list data.  Where would that
be coming from without a ListSource. 

You say I do not need to update another table  A DBLookupComboBox is
not used to update "another table".  It's used to update and present
in a user friendly way a coded value.

A simple example - say you have a Province / State table - call it
PROVINCE - and one of the data elements on this table is the three
character international country code - call it COUNTRY.  And you have
a country table with two fields:

cntrycode char(3) and cntryname char(25)

you could use a dblookupcombobox with ...

datasource: PROVINCESrc
datafield: COUNTRY
listsource: COUNTRYSrc
keyfield: cntrycode
listfield: cntryname

Assuming you had two "DataSource Components: PROVINCESrc and
COUNTRYSrc appropriately linked to their respective datasets and now
your user would see a nice user friendly "Canada" instead of "CAN" and
could change that code to another one through the pull down list - of
course you wouldn't normally be changing a province or state to be in
a different country.

HTH,

Doug

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thierrybo · 2010-03-25 12:00

Thanks for your explanation. I have to admit I was wrong with my
title   I was meaning "without a DataSource".. I just want to populate
the list from a database, without relationship with another
master/detail" table.