EntityDAC

DemoMainFormUnit.pas

unit DemoMainFormUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  Vcl.StdCtrls, Vcl.Grids, Vcl.ComCtrls,
  EntityDAC.Entity,
  EntityDAC.EntityConnection,
  EntityDAC.EntityContext,
  EntityDAC.DataProvider.UniDAC,
  SQLiteUniProvider,
  DemoClasses;

type
  TDemoMainForm = class(TForm)
    lbDepts: TListBox;
    lvEmps: TListView;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormShow(Sender: TObject);
    procedure lbDeptsClick(Sender: TObject);
  private
    FConnection: TEntityConnection;
    FContext: TEntityContext;

    FDepts: IEntityEnumerable<TDept>;
  public
    procedure Connect;
    procedure PopulateDepts;
    procedure PopulateEmps;
  end;

var
  DemoMainForm: TDemoMainForm;

implementation

{$R *.dfm}

{ TDemoMainForm }

procedure TDemoMainForm.FormCreate(Sender: TObject);
begin
  FConnection := TEntityConnection.Create;

  FContext := TEntityContext.Create;
  FContext.Connection := FConnection;
  FContext.ModelName := 'Demo';
end;

procedure TDemoMainForm.FormDestroy(Sender: TObject);
begin
  FConnection.Free;
  FContext.Free;
end;

procedure TDemoMainForm.FormShow(Sender: TObject);
begin
  Connect;
  PopulateDepts;
end;

procedure TDemoMainForm.lbDeptsClick(Sender: TObject);
begin
  PopulateEmps;
end;

procedure TDemoMainForm.Connect;
begin
  FConnection.ProviderName := 'UniDAC';
  FConnection.DialectName := 'SQLite';

  FConnection.ConnectionString := 'ProviderName=SQLite;Direct=True;DataBase=' + ExtractFilePath(Application.ExeName) + 'demo.db3';
  FConnection.Connect;
end;

procedure TDemoMainForm.PopulateDepts;
var
  Dept: TDept;
begin
  FDepts := FContext.GetEntities<TDept>;

  for Dept in FDepts do
    lbDepts.Items.Add(Dept.Dname);
end;

procedure TDemoMainForm.PopulateEmps;
var
  Emps: IEntityEnumerable<TEmp>;
  Emp: TEmp;
  Item: TListItem;
begin
  lvEmps.Items.Clear;
  if lbDepts.ItemIndex < 0 then
    Exit;

  Emps := FDepts[lbDepts.ItemIndex].Emps;

  for Emp in Emps do begin
    Item := lvEmps.Items.Add;
    Item.Caption := Emp.Ename;
    Item.SubItems.Add(Emp.Job);
  end;
end;

end.
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