Mega Code Archive
Delphi 4 Using UDL files to simplify ADO
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Title: Delphi 4 - Using UDL files to simplify ADO
Question: How do I get the ADO connection dialog up in D4
Answer:
Ado On Delphi 4- UDL Files to simplify deployment.
Recently I had to do some work with SQL Server 7 using D4. To minimise the need for ODBC configuration, I chose to use ADO. As D4 lacks the Adoconed (see article 1413) unit for displaying the ADO configuration dialogs, I found another way. Some of this code is derived from Marcus Neves article 1492 but there is some new stuff. If the UDL file is absent or corrupted, it displays the dialog then creates a new file. If however an existing configuration file is there then it loads it in and uses it.
For the ADO proper (which I havent shown- this just sets up the Ado connection string) I used the Ado components from http://www.alohaoi.com which are freeware with source and the best Ive found.
Just install the Ado components then put a button on the form to test this below.
For anyone that is interested, the Msdasc objects (which manage the connection dialogs) are contained in oledb32.dll- import the type library to get access to this.
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls,aoADODB_tlb,aomsdasc_tlb, aoADODB,ComObj;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
procedure loadudl;
procedure NewLink;
{ Private declarations }
public
ObjDataLink : Datalinks;
dbConnection : connection;
DataInitialize : IDataInitialize;
WUdlFile : Widestring;
AdoStr : string;
{ Public declarations }
end;
var
Form1: TForm1;
implementation
Const
UdlFile ='Adolink.udl';
procedure Tform1.loadudl;
var pwstr: pwidechar;
wUDLFile: array[0..MAX_PATH - 1] of WideChar;
begin
DataInitialize := CreateComObject(CLASS_DataLinks) as IDataInitialize;
StringToWideChar (UDLFile, @wUDLFile, MAX_PATH);
if Failed(DataInitialize.LoadStringFromStorage(wUDLFile, pwstr)) then
begin
ShowMessage('Link file corrupted or missing- please renew');
Newlink;
end
else
begin
adostr := pwstr;
end;
end;
procedure Tform1.NewLink;
var str: widestring;
wUDLFile: array[0..MAX_PATH - 1] of WideChar;
begin
str := '';
ObjDataLink := Codatalinks.Create;
if adostr '' then
begin
dbconnection := coconnection.create;
dbconnection.ConnectionString := adostr;
if ObjDataLink.PromptEdit(idispatch(dbconnection)) then
str := dbconnection.ConnectionString;
end
else
begin
dbconnection := ObjDataLink.PromptNew as _connection;
if assigned(dbconnection) then
str := dbconnection.ConnectionString;
end;
DataInitialize := CreateComObject(CLASS_DataLinks) as IDataInitialize;
StringToWideChar (UDLFile, @wUDLFile, MAX_PATH);
sysutils.DeleteFile(udlfile);
if Failed(DataInitialize.WriteStringToStorage(wUDLFile, pwidechar(Str), CREATE_NEW)) then
raise Exception.Create('Can''t write UDL to '+udlfile);
adostr := str;
end;
{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
begin
LoadUdl;
end;
end.
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