How to browse a Tobjectlist property via Rtti?

Question

my class has a Tobjectlist property:

TBaseModelo = class(TInterfacedPersistent)
public
    property ListaCamposValidacao: TObjectList<TCampoValidacao> read FListaCamposValidacao write FListaCamposValidacao;
end;

I need, through RTTI, select this property "Listfieldsvalidacao" and go through it to make an action, but I do not have much idea how to do.

Ctx := TRttiContext.Create;
try
  Typ := Ctx.GetType(Objeto.ClassType);      
  ????? 
  //Typ.GetProperty('ListaCamposValidacao').GetValue(Objeto);
finally
  Ctx.Free;
end;

Can someone help me, guide me on how to implement the code?

Answer 1

Here is a simple example of how to go through a property of type TObjectList<T>, no doubt there are other numerous ways to accomplish this task, as the goal here is to show the way and simplicity this is the best option. This example is not validating properties or without access methods getters&setters is writing and reading everything directly from the instance variables campos/atributos da classe

unit FrmPrincipal;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
  System.Generics.Collections, System.Rtti;

type

   TCampoValidacao = class
    private
      FId: string;
      FNome: string;
      FEndereco: string;
      FBairro: string;
    public
      property Id: string read FId write FId;
      property Nome: string read FNome write FNome;
      property Endereco: string read FEndereco write FEndereco;
      property Bairro: string read FBairro write FBairro;
   end;

   TBaseModelo = class(TInterfacedObject)
  private
    FListaCamposValidacao: TObjectList<TCampoValidacao>;
  public
      property ListaCamposValidacao: TObjectList<TCampoValidacao> read FListaCamposValidacao write FListaCamposValidacao;
      constructor Create;
      destructor Destroy; override;
  end;

  TModeloX = Class(TBaseModelo )
    private
    FId:string;
    FNome: string;
    FEndereco: string;
    FBairro: string;
    public
      property Id: string read FId write FId;
      property Nome: string read FNome write FNome;
      property Endereco: string read FEndereco write FEndereco;
      property Bairro: string read FBairro write FBairro;
  End;

  TForm1 = class(TForm)
    btGerar: TButton;
    Memo1: TMemo;
    procedure btGerarClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btGerarClick(Sender: TObject);
var
    id: TGuid;
    meuModelo:  TModeloX;
    campoValidacao: TCampoValidacao;
    ctxRtti  : TRttiContext;
    typeRtti : TRttiType;
    propRtti : TRttiProperty;
    I: Integer;
begin
   meuModelo := TModeloX.Create;
   for I := 0 to 50 do
   begin
     CreateGUID(id);
     campoValidacao := TCampoValidacao.Create;
     campoValidacao.Id := System.SysUtils.GUIDToString( id );
     campoValidacao.Nome := 'MAURO' + IntToStr( i );
     campoValidacao.Endereco := 'RUA PEDRO PEREIRA - Nº ' + IntToStr( i );
     campoValidacao.Bairro := 'Vila Martins ';
     meuModelo.ListaCamposValidacao.Add(campoValidacao);
   end;
   campoValidacao := nil;

   ctxRtti  := TRttiContext.Create;

   for campoValidacao in meuModelo.ListaCamposValidacao do
   begin
     typeRtti := ctxRtti.GetType( campoValidacao.ClassType );
     for propRtti in typeRtti.GetProperties do
       Memo1.Lines.Add( propRtti.Name+': ' +  propRtti.GetValue( campoValidacao).ToString );
   end;
  ctxRtti.Free;
end;

{ TBaseModelo }

constructor TBaseModelo.Create;
begin
  FListaCamposValidacao := TObjectList<TCampoValidacao>.Create;
end;

destructor TBaseModelo.Destroy;
begin
  if Assigned( FListaCamposValidacao ) then
    FListaCamposValidacao.Free;
  inherited;
end;

end.

Research source: http://edn.embarcadero.com/article/41728