SQLite Connection Errors
lazarus / 16-Databases

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SteveF · 2009-04-06 20:04

I'm running into a problem in my continuing quest to figure out how
Lazarus & Free Pascal work.  I've used & modified a tutorial for
SQLite datasets posted here:

http://www.geocities.com/camara_luiz/docs/dataset/dataset-
tutorial-03.html

My modifications work just fine as long as I leave the code that
establishes the connection to the SQLite data file in the FormCreate
event, as in the original tutorial.  As soon as the code is moved out
of the FormCreate event, I start getting the following compiler
errors:

fmain.pas(80,16) Error: Identifier not found "NamesDS"
fmain.pas(80,16) Error: Expression type must be class or record type
fmain.pas(82,13) Error: Identifier not found "FileName"
fmain.pas(83,14) Error: Identifier not found "TableName"
fmain.pas(84,23) Error: Identifier not found "TableExists"
fmain.pas(86,14) Error: Identifier not found "FieldDefs"
fmain.pas(87,14) Error: Identifier not found "FieldDefs"
fmain.pas(88,14) Error: Identifier not found "FieldDefs"
fmain.pas(89,14) Error: Identifier not found "FieldDefs"
fmain.pas(90,16) Error: Identifier not found "CreateTable"
fmain.pas(92,8) Error: Identifier not found "SQL"
fmain.pas(93,8) Error: Identifier not found "Open"

the same set of errors is repeated for each dataset in the
application.  Even something as simple as moving the code to its own
procedure, and calling that procedure from the FormCreate event
generates these errors.

The ultimate goal here is to allow the hypothetical user to select the
name and location of the SQLite data file used by the application.  As
long as the link must be done in the FormCreate event, I don't see how
that can happen.

What needs to be done to get this to work?  Relevant code follows.

SteveF


procedure LinkToFile;
begin                //setup link to data file
 ForceDirectories(GetAppConfigDir(False));
  With NamesDS do
  begin
   FileName := IncludeTrailingPathDelimiter(GetAppConfigDir(False)) +
'addressbook.db';
   TableName := 'Names';
   if not TableExists then
   begin
    FieldDefs.Clear;
    FieldDefs.Add('NameID',ftAutoInc);
    FieldDefs.Add('Fname',ftString);
    FieldDefs.Add('Lname',ftString);
    CreateTable;
   end;
   SQL := 'SELECT * FROM Names ORDER BY Lname, Fname';
   Open;
  end;
  With AddrDS do
  begin
   FileName := IncludeTrailingPathDelimiter(GetAppConfigDir(False)) +
'addressbook.db';
   TableName := 'Addresses';
   if not TableExists then
   begin
    FieldDefs.Clear;
    FieldDefs.Add('AddrID',ftAutoInc);
    FieldDefs.Add('NameID',ftInteger);
    FieldDefs.Add('AddrType',ftString);
    FieldDefs.Add('Company',ftString);
    FieldDefs.Add('Address',ftString);
    FieldDefs.Add('Town',ftString);
    FieldDefs.Add('State',ftString);
    FieldDefs.Add('ZIP',ftString);
    FieldDefs.Add('Nation',ftString);
    CreateTable;
   end;
   Open;
  end;
  With PhonesDS do
  begin
   FileName := IncludeTrailingPathDelimiter(GetAppConfigDir(False)) +
'addressbook.db';
   TableName := 'Phones';
   if not TableExists then
   begin
    FieldDefs.Clear;
    FieldDefs.Add('PhoneID',ftAutoInc);
    FieldDefs.Add('NameID',ftInteger);
    FieldDefs.Add('PhoneType',ftString);
    FieldDefs.Add('Number',ftString);
    CreateTable;
   end;
   Open;
  end;
  With wwwDS do
  begin
   FileName := IncludeTrailingPathDelimiter(GetAppConfigDir(False)) +
'addressbook.db';
   TableName := 'WWW';
   if not TableExists then
   begin
    FieldDefs.Clear;
    FieldDefs.Add('wwwID',ftAutoInc);
    FieldDefs.Add('NameID',ftInteger);
    FieldDefs.Add('wwwType',ftString);
    FieldDefs.Add('wwwData',ftString);
    CreateTable;
   end;
   Open;
  end;
end;

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Vincent Snijders · 2009-04-07 07:36

Make LinkToFile a method of the form which contains the data access
components.

procedure TForm1.LinkToFile;

Don't forget to add this method in the class declaration too.

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SteveF · 2009-04-13 20:16

Thanks, Vincent.  Your changes solved the problem.  I’m still learning
about things here, and now I know to make sure that any procedures I
write that are not events bound to a form or its controls do get bound
to the form with which its being used.  After I made the change to the
one procedure, I had some others which I added in the same manner, and
they worked with no problems.

Steve