List Binding Example

Use TeeGrid with generic TList<T> and TObjectList<T> collections

Overview

TeeGrid supports direct binding to generic TList<T> and TObjectList<T> collections, providing automatic UI updates as your list changes.

Basic TList Binding

TList<TPerson>

uses
  System.Generics.Collections, Tee.GridData, Tee.GridData.Rtti;

var
  MyPersons: TList<TPerson>;

procedure TFormGridTList.FormCreate(Sender: TObject);
begin
  // Create and fill the list
  MyPersons := TList<TPerson>.Create;
  FillMyData(MyPersons, 20);  // Add 20 persons

  // Bind list to grid
  TeeGrid1.Data := TVirtualListData<TPerson>.Create(MyPersons);
  
  // Enable automatic row height
  TeeGrid1.Rows.Height.Automatic := True;
end;

procedure TFormGridTList.FormDestroy(Sender: TObject);
begin
  MyPersons.Free;
end;

TObjectList Binding

TObjectList<TCar>

var
  MyCars: TObjectList<TCar>;

procedure CarsExample;
begin
  // Create and fill object list
  MyCars := TObjectList<TCar>.Create;  // Will auto-free objects
  FillMyData(MyCars, 20);

  // Bind to grid
  TeeGrid1.Data := TVirtualObjectListData<TCar>.Create(MyCars);
end;

TObjectList<T> automatically manages the lifetime of its objects when freed.

Controlling Visibility

Member Visibility

Control which fields and properties are displayed:

uses
  System.TypInfo;

const
  PublicAndPublished = [TMemberVisibility.mvPublic, TMemberVisibility.mvPublished];

procedure PersonsExample;
begin
  TeeGrid1.Data := TVirtualListData<TPerson>.Create(
    MyPersons,
    PublicAndPublished,      // Which members to show
    TRttiMembers.Both,       // Show fields AND properties
    False                    // Don't include ancestor members
  );
end;

Including Ancestor Members

// Show ancestor class members (e.g., TVehicle.Brand for TCar)
TeeGrid1.Data := TVirtualObjectListData<TCar>.Create(
  MyCars,
  PublicAndPublished,
  TRttiMembers.Both,
  True  // Include ancestor members
);

Complete Example from Demos

From Unit_TList.pas in the VirtualData demos:

unit Unit_TList;

interface

uses
  System.SysUtils, System.Classes, FMX.Forms, FMX.Controls,
  FMXTee.Control, FMXTee.Grid, FMX.ListBox, FMX.StdCtrls;

type
  TFormGridTList = class(TForm)
    TeeGrid1: TTeeGrid;
    CBTheme: TComboBox;
    CBExample: TComboBox;
    CBAncestor: TCheckBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure CBThemeChange(Sender: TObject);
    procedure CBExampleChange(Sender: TObject);
    procedure CBAncestorChange(Sender: TObject);
  private
    procedure CarsExample;
    procedure CreateExample;
    procedure PersonsExample;
  end;

implementation

uses
  System.TypInfo, System.Generics.Collections,
  Tee.GridData, Tee.GridData.Rtti, Tee.Grid.Themes,
  Unit_MyData;

var
  MyPersons: TList<TPerson>;
  MyCars: TObjectList<TCar>;

const
  PublicAndPublished = [TMemberVisibility.mvPublic, TMemberVisibility.mvPublished];

procedure TFormGridTList.PersonsExample;
begin
  // Bind TList<TPerson> to grid
  TeeGrid1.Data := TVirtualListData<TPerson>.Create(
    MyPersons,
    PublicAndPublished,
    TRttiMembers.Both,
    CBAncestor.IsChecked
  );
  
  // Alternative way:
  // TeeGrid1.Data := TVirtualData<TList<TPerson>>.Create(MyPersons);
end;

procedure TFormGridTList.CarsExample;
begin
  // Bind TObjectList<TCar> to grid
  TeeGrid1.Data := TVirtualObjectListData<TCar>.Create(
    MyCars,
    PublicAndPublished,
    TRttiMembers.Both,
    CBAncestor.IsChecked
  );
end;

procedure TFormGridTList.CreateExample;
begin
  if CBExample.ItemIndex = 0 then
    PersonsExample
  else
    CarsExample;
end;

procedure TFormGridTList.CBThemeChange(Sender: TObject);
begin
  case CBTheme.ItemIndex of
    1: TGridThemes.Default.ApplyTo(TeeGrid1.Grid);
    2: TGridThemes.Black.ApplyTo(TeeGrid1.Grid);
    3: TGridThemes.iOS.ApplyTo(TeeGrid1.Grid);
    4: TGridThemes.Android.ApplyTo(TeeGrid1.Grid);
  end;
end;

procedure TFormGridTList.CBAncestorChange(Sender: TObject);
begin
  CreateExample;  // Recreate with/without ancestor members
end;

procedure TFormGridTList.CBExampleChange(Sender: TObject);
begin
  CreateExample;
  CBAncestor.Enabled := CBExample.ItemIndex = 1;  // Only for Cars
end;

procedure TFormGridTList.FormCreate(Sender: TObject);
begin
  // Create sample data
  MyPersons := TList<TPerson>.Create;
  FillMyData(MyPersons, 20);

  MyCars := TObjectList<TCar>.Create;
  FillMyData(MyCars, 20);

  // Display initial example
  CreateExample;

  // Enable automatic row heights
  TeeGrid1.Rows.Height.Automatic := True;
end;

procedure TFormGridTList.FormDestroy(Sender: TObject);
begin
  MyPersons.Free;
  MyCars.Free;  // Also frees all car objects
end;

end.

Key Concepts

TVirtualListData vs TVirtualObjectListData

• TVirtualListData: For TList<T> of records or simple types
• TVirtualObjectListData: For TList<T> or TObjectList<T> of objects

Member Filtering

Control what gets displayed:

type
  TMemberVisibility = (mvPrivate, mvProtected, mvPublic, mvPublished);
  TRttiMembers = (Fields, Properties, Both);

// Examples:
[TMemberVisibility.mvPublic]              // Only public members
[TMemberVisibility.mvPublished]           // Only published members
[TMemberVisibility.mvPublic, mvPublished] // Both public and published

TRttiMembers.Fields      // Only fields
TRttiMembers.Properties  // Only properties  
TRttiMembers.Both        // Both fields and properties

Live Updates

Changes to the list automatically reflect in the grid:

// Add a new item
var
  NewPerson: TPerson;
begin
  NewPerson.Name := 'John';
  NewPerson.Age := 30;
  MyPersons.Add(NewPerson);
  TeeGrid1.Invalidate;  // Refresh display
end;

// Remove an item
MyPersons.Delete(5);
TeeGrid1.Invalidate;

Advanced Usage

Custom Visibility

// Show only public fields (no properties)
TeeGrid1.Data := TVirtualListData<TPerson>.Create(
  MyPersons,
  [TMemberVisibility.mvPublic],
  TRttiMembers.Fields,
  False
);

Combining with Themes

uses
  Tee.Grid.Themes;

// Apply a theme after binding data
TGridThemes.iOS.ApplyTo(TeeGrid1.Grid);

Performance Considerations

• TeeGrid uses virtual rendering - only visible rows are drawn
• Lists of 10,000+ items perform smoothly
• RTTI reflection is done once during binding, not during rendering

Common Patterns

Record Lists

var
  Items: TList<TMyRecord>;
begin
  Items := TList<TMyRecord>.Create;
  try
    // Fill list
    TeeGrid1.Data := TVirtualListData<TMyRecord>.Create(Items);
  finally
    // Don't free Items while grid is using it!
  end;
end;

Object Lists with Ownership

var
  Objects: TObjectList<TMyObject>;
begin
  Objects := TObjectList<TMyObject>.Create(True);  // Owns objects
  // TObjectList will free all objects when destroyed
end;

Features Demonstrated

• Binding TList<T> of records
• Binding TObjectList<T> of objects
• Controlling member visibility
• Including/excluding ancestor members
• Automatic column generation from RTTI
• Live data updates

Next Steps

• Explore Array Binding for array data
• Learn about Custom Editors for editing
• See Virtual Mode for maximum control

Related Examples

• Array Binding
• Dataset Binding
• Virtual Mode