How to get Dbgrid to display a dropdown list
lazarus / 16-Databases

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talorigomat · 2014-10-05 04:01

I have a dataset named assignments which contains an assignment id,
employee id and department id and its data is being displayed in a
dbgrid.  I have another dataset holding department information
(department id, department name).

I'm trying to setup the dbgrid so that it displays the department name
which it looks up from the department dataset. On the assignments
dataset I've opened the 'edit fields' window added a new field as type
lookup and completed the required information, ie:
Key field - Orgid
dataset - department
Lookupkeys - Orgid
Result Fields - DeptName

At design time the dbgrid displays the value.  However when I run the
program I get an error stating that "operation cannot be performed on
an inactive dataset.

All my datasets and transactions are made active in the forms onShow
method.  If I remove the lookup field from the dbgrid the program runs
without this error message.

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sin_dragan · 2014-10-05 06:38

Hi, can you show code or screenshot, I'm not sure that I understand
the problem?

You want to show department name in dbgrid, you can join tables in
your query that would return dataset with department name. If you want
to edit a record then you should use dblookupcombobox component in
edit form and set ListSource to Department list and KeyField and
DataField to department id.

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talorigomat · 2014-10-07 14:20

I've attached a screenshot of what I'm attempting to do.  This was
orignially done using microsoft access and I'm rewriting it using
Lazarus (version 1.2.4) and Firebird (version 2.5.2).  The Specialty
column has a dropdown list box  from which the user can select an
item.

I attempted to follow the advice found on the following website:

http://www.linkedin.com/groups/ASK-display-combox-as-
value-4558772.S.197174056 (see Reshi M. reply which is 8th in the
list).

All my datasets and transactions are set to active in the form first
opens by the FormShow event. 
Code: [Select]procedure TfrmGuidance.FormShow(Sender: TObject);
begin
  qryguidance.Active := True;
  qryStatus.Active := True;
  qryType.Active :=True;
  qryOrg.Active:= True;
  qryguidance.Refresh;  // Values in combobox won't display on first
open without
  qryAssign.Active:= True;
  trnAssign.Active:=True;
  trnlookups.Active:= True;
qryOrg is the dataset for the organisation table and it's transaction
property is linked to trnlookups.

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TraumTaenzerDieter · 2014-10-07 15:00

KeyField and LookupKeys have same name: is that correct??

Key field - Orgid : must be the Id in the Detail-Dataset!
dataset - department : is that the Lookup-Dataset?
Lookupkeys - Orgid : Same name?? are you sure??
Result Fields - DeptName : what will be displayed in the grid instead
of the Key-Field,
so it must come from the lookup-dataset.

The error suggests that you open your Detail-Dataset before you open
your Lookup-Dataset: could be verified by breakpoints.

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talorigomat · 2014-10-10 07:27

After restarting my computer the dropdown list in the dbgrid seems to
be working fine. 

To answer TraumTaenzerDieter question, the KeyField and LookupKeys
have similar names.

OrgId is the name of the key field in the department table.  The
assignment table also has a field named OrgId also, which of course
will hold the id of the depart that was selected.

Many thanks for helping.