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Problem creating a lookup field at run-time

I am having troubles creating a lookup field at runtime. The problem that I am having seems to be that since I am creating a field for the table, I am losing all of the previous fields when I set the active property to true. This seems very puzzling to me. Below is a code snippet of what I am trying to do.

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procedure TForm1.Button1Click(Sender: TObject);
var
Table1, Table2 : TTable;
LookupFld:TStringField;

begin
Table1 := TTable.Create(Form1);
Table1.Databasename := 'REPDATA';
Table1.Tablename := 'P';

Table2 := TTable.Create(Form1);
Table2.Databasename := 'REPDATA';
Table2.Tablename := 'C';
Table2.Active := TRUE;

// I'm adding these lines just to show a comparison
Table1.Active := TRUE; // Fieldcount = 91
Table1.Active := FALSE;

LookupFld:=TStringField.Create(Table1);
LookupFld.FieldName:='FNAME';
LookupFld.keyfields := 'CKEY';
LookupFld.lookupdataset := Table2;
LookupFld.lookupKeyFields := 'PRKEY';
LookupFld.lookupResultField := 'NAME';
LookupFld.fieldkind := fkLookup;
LookupFld.Dataset:=Table1;

Table1.Active:=true; // Fieldcount = 1

Table1.Free;
Table2.Free;
end;

When I try to open the table, I get an error stating that field "CKEY" is not found. This field does exist in the table. I don't understand why it is that when I create a field for a table, the fieldcount is 1, yet when I just open a table, the fieldcount is as it should be. I've also tried creating the "CKEY" field and then this works, however the fieldcount is then 2 and the other fields are not available.

Any help is appreciated. Thanks in advance.

Sean

dwwang

This is some how complex to explain:

If you want to add a field to the table, you must firstly add all fields (exist in your table)to it, i.e., to right click the table and then select Fields Editor - "Add Fields..." to add all needed fields to the TTable. This will resolve your losing fields problem.

BlackMan

Is has something to do with the way Delphi adds the fields. I had the same problem once and found a workaround, I'll dig the code up..

MaxdOut

ASKER

dwwang, your proposed answer would be a viable solution, however the key to this is that I need to create everything at runtime (both the tables and the fields) and thus I can't add the fields in this manner. Do I need to manually add every field to the table in order for this to work?

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BlackMan

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MaxdOut

ASKER

Thank you very much BlackMan.

You helped me solve a problem which has been slowing me down for a few days. Very much appreciated!

MaxdOut

dwwang

Oh, I was so unlucky that was unnable to post my answer here before the question finished.

I have a real tricky solution for this problem, it's result-equivalent to BlackMan's, but better.

Hmmm... I decide to keep it until another person met such kind of problem and provide another 200 points! :-))