TDispatchConnection.LoginPrompt Property

Specifies whether a login dialog appears immediately before opening a new connection.

Pascal

property LoginPrompt: Boolean;

C++

__property Boolean LoginPrompt;

Description

Set LoginPrompt to true to provide login support when establishing a connection. LoginPrompt controls two things: the occurrence of the OnLogin event, and the appearance of a default login dialog that prompts users for a name and password when you include DBLogDlg.hpp in your unit (C++) or add DBLogDlg to your uses clause (Delphi). When the OnLogin event occurs and when the default login dialog appears depend on the type of connection component:

For TDatabase, TIBDatabase, and TSQLConnection, the dialog appears after the BeforeConnect event and before the AfterConnect event, unless you supply an OnLogin event handler. If there is an OnLogin event handler, that event occurs in place of the login dialog, and there is no need to include DBLogDlg.hpp in your unit (C++) or add DBLogDlg to your uses clause (Delphi). If correct values for the user name and password are not supplied in the dialog or by the OnLogin event handler, the connection fails. The OnLogin event does not fire unless LoginPrompt is set to true.

For TADOConnection components, the dialog appears after the OnWillConnect event and before the BeforeConnect event. If there is an OnLogin event handler, that event occurs after the login dialog. If you do not include DBLogDlg.hpp in your unit (C++) or add DBLogDlg to your uses clause (Delphi), the OnLogin event occurs but there is no default login dialog. If correct values for the user name and password are not supplied in the dialog or by the OnLogin event handler, the connection fails. The OnLogin event does not fire unless LoginPrompt is set to true.

For DataSnap SOAP connection components, the dialog appears after the OnGetUsername event and before the BeforeConnect, AfterConnect, and OnLogin events. If the user cancels from the login dialog, no attempt is made to open a connection.

When LoginPrompt is false, the application must supply user name and password values programmatically:

For TDatabase, the user name and password can be supplied as USER_NAME and PASSWORD parameters in the Params property.

For TADOConnection, the user name and password can be supplied as the ConnectionString property.

For TSQLConnection, the user name, password, and database can be supplied as UserName, Password, and Database parameters in the Params property, or provided as connection parameters associated with the connection name.

For DataSnap SOAP connection components, there is no built-in use for the user name and password supplied by the login dialog. (The UserName and Password properties of TWebConnection are unrelated).

Warning: Storing hard-coded user name and password entries as property values or in code for an OnLogin event handler can compromise server security.

C++ Examples:

Copy Code

//
//This example demostrates the use of ADO for database conectivity.
//Example assumes that a TDBGrid is placed on the form.
//
void __fastcall TForm2::FormCreate(TObject *Sender)
{
    /* Login details */
    String UserName = "db_user_name";
    String PassWord = "db_pass_word";
    String Server = "my.db.server";

    /* Connection String */
    String ConnString =
        "Provider=SQLOLEDB.1;Persist Security Info=False;";
    ConnString +=
        "User ID=%s;Password=%s;Data Source=%s;Use Procedure for Prepare=1;";
    ConnString +=
        "Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;";
    ConnString +=
        "Tag with column collation when possible=False";

    /* SQL Query */
    String SQLStr = "SELECT * FROM customer WHERE customer_id = :AnId;";

    /* All ADO variables */
    TADOConnection* ADOConn;
    TADOQuery* ADOQuery;
    TDataSource* DataSrc;
    TParameter* Param;

    /* Create an ADO connection */
    ADOConn = new TADOConnection(this);

    /* Setup the connection string */
    ADOConn->ConnectionString = Format(ConnString,
        ARRAYOFCONST((UserName, PassWord, Server)));

    /* Disable login prompt */
    ADOConn->LoginPrompt = False;

    try
    {
        ADOConn->Connected = true;
    }
    catch (EADOError *e)
    {
        MessageDlg("Error while connecting", mtError,
                      TMsgDlgButtons() << mbOK, 0);
        return;
    }

    /* Create the query */
    ADOQuery = new TADOQuery(this);
    ADOQuery->Connection = ADOConn;
    ADOQuery->SQL->Add(SQLStr);

    /* Update the parameter that was parsed from the SQL query: AnId */
    Param = ADOQuery->Parameters->ParamByName("AnId");
    Param->DataType = ftInteger;
    Param->Value = 1;

    /* Set the query to Prepared - will improve performance */
    ADOQuery->Prepared = true;

    try
    {
        ADOQuery->Active = true;
    }
    catch (EADOError *e)
    {
        MessageDlg("Error while connecting", mtError,
                      TMsgDlgButtons() << mbOK, 0);
        return;
    }

    /* Create the data source */
    DataSrc = new TDataSource(this);
    DataSrc->DataSet = ADOQuery;
    DataSrc->Enabled = true;

    /* Finally initilalize the grid */
    DBGrid1->DataSource = DataSrc;
}

Delphi Examples:

Copy Code

{
This example demostrates the use of ADO for database conectivity.
Example assumes that a TDBGrid is placed on the form.
}
procedure TForm2.FormCreate(Sender: TObject);
const
  { Connection string }
  ConnString =
  'Provider=SQLOLEDB.1;Persist Security Info=False;' +
  'User ID=%s;Password=%s;Data Source=%s;Use Procedure for Prepare=1;' +
  'Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;'+
  'Tag with column collation when possible=False';

  { SQL Query }
  SQLStr = 'SELECT * FROM customer WHERE customer_id = :AnId;';

  { User access }
  UserName = 'db_user_name';
  PassWord = 'db_pass_word';
  Server = 'my.db.server';

var
  ADOConn  : TADOConnection;
  ADOQuery : TADOQuery;
  DataSrc  : TDataSource;
  Param    : TParameter;

begin
  { Create an ADO connection }
  ADOConn := TADOConnection.Create(Self);
  { Setup the provider engine }

  { Setup the connection string }
  ADOConn.ConnectionString := Format(ConnString,
    [UserName, PassWord, Server]);

  { Disable login prompt }
  ADOConn.LoginPrompt := False;

  try
    ADOConn.Connected := True;
  except
    on e: EADOError do
    begin
      MessageDlg('Error while connecting', mtError,
                  [mbOK], 0);

      Exit;
    end;
  end;

  { Create the query }
  ADOQuery := TADOQuery.Create(Self);
  ADOQuery.Connection := ADOConn;
  ADOQuery.SQL.Add(SQLStr);

  { Update the parameter that was parsed from the SQL query: AnId }
  Param := ADOQuery.Parameters.ParamByName('AnId');
  Param.DataType := ftInteger;
  Param.Value := 1;

  { Set the query to Prepared - will improve performance }
  ADOQuery.Prepared := true;

  try
    ADOQuery.Active := True;
  except
    on e: EADOError do
    begin
      MessageDlg('Error while doing query', mtError,
                  [mbOK], 0);

      Exit;
    end;
  end;

  { Create the data source }
  DataSrc := TDataSource.Create(Self);
  DataSrc.DataSet := ADOQuery;
  DataSrc.Enabled := true;

  { Finally initilalize the grid }
  DBGrid1.DataSource := DataSrc;
end;