Componentes.Terceros.RemObjects/internal/6.0.43.801/1/RemObjects Samples/Data Abstract for Delphi/Dynamic Where/fClientForm.pas

unit fClientForm;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls,
  uROClient, uROClientIntf, uRORemoteService, uROBinMessage,
  uROPoweredByRemObjectsButton, uDAPoweredByDataAbstractButton, ExtCtrls, Grids,
  DBGrids, uDAInterfaces;

type
  TClientForm = class(TForm)
    Panel1: TPanel;
    DAPoweredByDataAbstractButton1: TDAPoweredByDataAbstractButton;
    Label1: TLabel;
    cbConditions: TComboBox;
    Panel2: TPanel;
    Label2: TLabel;
    edXML: TMemo;
    Panel4: TPanel;
    btLoad: TButton;
    btValidate: TButton;
    dgData: TDBGrid;
    procedure FormCreate(Sender: TObject);
    procedure cbConditionsChange(Sender: TObject);
    procedure btValidateClick(Sender: TObject);
    procedure btLoadClick(Sender: TObject);
  private
    { Private declarations }
    function GetTemplateWhereExpression: TDAWhereExpression;
    procedure ShowXML(aExpr: TDAWhereExpression);
  public
    { Public declarations }
  end;

var
  ClientForm: TClientForm;

implementation

uses
  fClientDataModule;  
  
{$R *.dfm}

procedure TClientForm.btLoadClick(Sender: TObject);
var
  wb: TDAWhereBuilder;
  expr: TDAWhereExpression;
  expArr: array of TDAWhereExpression;
begin
   wb := TDAWhereBuilder.Create;
   try
    with ClientDataModule do begin
      tbl_Workers.ClearRows(true);
      if Trim(edXML.Text) <> ''
      then expr := wb.XMLToExpression(edXML.Text)
      else expr := nil;
      SetLength(expArr, 1);
      expArr[0] := expr;
      RemoteDataAdapter.Fill([tbl_Workers], expArr);
    end;
   except
     on E: Exception do ShowMessage('Error loading data: ' + E.Message);
   end;
   wb.Free;
end;

procedure TClientForm.btValidateClick(Sender: TObject);
var
  expr: TDAWhereExpression;
  wb: TDAWhereBuilder;
begin
  wb := TDAWhereBuilder.Create;
  try
    try
      expr := wb.XMLToExpression(edXML.Text);
      expr.Validate;
      ShowMessage('XML Where expression is valid');
    except
      on E: Exception do ShowMessage('XML Where expression is INVALID: ' + E.Message);
    end;
  finally
    wb.Free;
  end;
end;

procedure TClientForm.cbConditionsChange(Sender: TObject);
var
  expr: TDAWhereExpression;
begin
  expr := GetTemplateWhereExpression;
  ShowXML(expr);
end;

procedure TClientForm.FormCreate(Sender: TObject);
begin
  // TODO: until DynamicRequest bug fixed
  //ClientDataModule.Login;
  Application.Title := ClientForm.Caption;
  cbConditionsChange(nil);
end;

function TClientForm.GetTemplateWhereExpression: TDAWhereExpression;
var
  wb: TDAWhereBuilder;
begin
  Result := nil;
  wb := TDAWhereBuilder.Create;
  with wb, ClientDataModule.tbl_Workers do
    case cbConditions.ItemIndex of
    //Position is Sales Manager
    0: Result := NewBinaryExpression(
        NewField(LogicalName, 'WorkerPosition'),
        NewConstant('Sales Manager', datString),
        dboEqual);
    //Job is Sales Manager And City is Chicago
    1: Result := NewBinaryExpression(
        NewBinaryExpression(
          NewField(LogicalName, 'WorkerPosition'),
          NewConstant('Sales Manager', datString),
          dboEqual),
        NewBinaryExpression(
          NewField(LogicalName, 'WorkerCity'),
          NewConstant('Chicago IL', datString),
          dboEqual),
        dboAnd);
    //City is Chicago or Atlanta
    2: Result := NewBinaryExpression(
        NewField(LogicalName, 'WorkerCity'),
        NewList([NewConstant('Chicago IL', datString), NewConstant('Atlanta CA', datString)]),
        dboIn);
    //FirstName doesn't begin with A
    3: Result := NewUnaryExpression(
        NewBinaryExpression(
          NewField(LogicalName, 'WorkerFirstName'),
          NewConstant('A%', datString),
          dboLike),
        duoNot);
    //(Position is Sales Representative Or Zip is NULL) And (City is Kirkland or Seattle)
    4: Result := NewBinaryExpression(
        NewBinaryExpression(
          NewBinaryExpression(
            NewField(LogicalName, 'WorkerPosition'),
            NewConstant('Sales Representative', datString),
            dboEqual),
          NewBinaryExpression(
            NewField(LogicalName, 'WorkerZip'),
            NewNull,
            dboEqual),
          dboOr),
        NewBinaryExpression(
          NewField(LogicalName, 'WorkerCity'),
          NewList(
            [NewConstant('Kirkland', datString),
             NewConstant('Seattle', datString)]
          ),
          dboIn),
        dboAnd);
    // Wrong condition - incorrect field name
    6: Result := NewBinaryExpression(
        NewField(LogicalName, 'Country_Name'),
        NewConstant('UK', datString),
        dboEqual);
    end;
  wb.Free;
end;

procedure TClientForm.ShowXML(aExpr: TDAWhereExpression);
var
  wb: TDAWhereBuilder;
begin
  edXML.Clear;
  if Assigned(aExpr) then begin
    wb := TDAWhereBuilder.Create;
    wb.Expression := aExpr;
    edXML.Text := wb.Xml;
    wb.Free;
  end;
end;

end.