Array Binding Example

Display and edit arrays of records, objects, and simple types in TeeGrid

Overview

TeeGrid can display and edit different kinds of arrays using RTTI (Runtime Type Information). This provides automatic column generation from your data structures.

Array of Records

The most common use case is displaying an array of records:

type
  TAddress = record
    Street: String;
    Number: Integer;
  end;

  TPerson = record
    Name: String;
    Address: TAddress;      // Sub-record
    BirthDate: TDateTime;
    Children: Integer;
    IsDeveloper: Boolean;
    Height: Single;
  end;

var
  MyData: TArray<TPerson>;

procedure TFormArray.BRecordClick(Sender: TObject);
begin
  SetLength(MyData, 10);
  FillMyData(MyData);  // Fill with sample data

  // Bind array to grid - automatically creates columns from record fields
  TeeGrid1.Data := TVirtualData<TArray<TPerson>>.Create(MyData);
end;

Array of Simple Types

Array of Integer

var
  MyIntegers: TArray<Integer>;

procedure TFormArray.BIntegerClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyIntegers, 100);

  for t := 0 to High(MyIntegers) do
    MyIntegers[t] := Random(1000);

  // Simple syntax
  TeeGrid1.Data := TVirtualArrayData<Integer>.Create(MyIntegers);
  
  // Alternative (equivalent)
  // TeeGrid1.Data := TVirtualData<TArray<Integer>>.Create(MyIntegers);
end;

Array of Float

var
  MyFloats: TArray<Single>;

procedure TFormArray.BFloatClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyFloats, 200);

  for t := 0 to High(MyFloats) do
    MyFloats[t] := Random(1000) * 0.01;

  TeeGrid1.Data := TVirtualData<TArray<Single>>.Create(MyFloats);
end;

Array of String

var
  MyStrings: TArray<String>;

procedure TFormArray.BStringClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyStrings, 10);

  for t := 0 to High(MyStrings) do
    MyStrings[t] := 'Item ' + IntToStr(t);

  TeeGrid1.Data := TVirtualData<TArray<String>>.Create(MyStrings);
end;

Array of Objects

type
  TVehicle = class(TPersistent)
  public
    Brand: String;
  end;

  TCar = class(TVehicle)
  private
    FSpeed: Double;
  public
    Wheels: Word;
    Driver: TPerson;
    property Speed: Double read FSpeed write FSpeed;
  end;

var
  MyCars: TArray<TCar>;

procedure TFormArray.BTObjectClick(Sender: TObject);
begin
  SetLength(MyCars, 10);
  FillMyData(MyCars);  // Create and populate car objects

  TeeGrid1.Data := TVirtualData<TArray<TCar>>.Create(MyCars);
end;

Remember to free object instances in arrays when you’re done:

procedure Clean(const ACars: TArray<TCar>);
var
  t: Integer;
begin
  for t := Low(ACars) to High(ACars) do
    ACars[t].Free;
end;

Complete Example from Demos

From Unit_Array.pas in the VirtualData demos:

unit Unit_Array;

interface

uses
  Vcl.Forms, VCLTee.Control, VCLTee.Grid, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TFormArray = class(TForm)
    TeeGrid1: TTeeGrid;
    BInteger: TButton;
    BFloat: TButton;
    BString: TButton;
    BTObject: TButton;
    BRecord: TButton;
    procedure FormCreate(Sender: TObject);
    procedure BIntegerClick(Sender: TObject);
    procedure BFloatClick(Sender: TObject);
    procedure BStringClick(Sender: TObject);
    procedure BRecordClick(Sender: TObject);
    procedure BTObjectClick(Sender: TObject);
  end;

implementation

uses
  Unit_MyData, Tee.GridData, Tee.GridData.Rtti;

var
  MyIntegers: TArray<Integer>;
  MyFloats: TArray<Single>;
  MyStrings: TArray<String>;
  MyData: TArray<TPerson>;
  MyCars: TArray<TCar>;

procedure TFormArray.BIntegerClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyIntegers, 100);
  for t := 0 to High(MyIntegers) do
    MyIntegers[t] := Random(1000);

  TeeGrid1.Data := TVirtualArrayData<Integer>.Create(MyIntegers);
end;

procedure TFormArray.BFloatClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyFloats, 200);
  for t := 0 to High(MyFloats) do
    MyFloats[t] := Random(1000) * 0.01;

  TeeGrid1.Data := TVirtualData<TArray<Single>>.Create(MyFloats);
end;

procedure TFormArray.BStringClick(Sender: TObject);
var
  t: Integer;
begin
  SetLength(MyStrings, 10);
  for t := 0 to High(MyStrings) do
    MyStrings[t] := 'Sample ' + IntToStr(t);

  TeeGrid1.Data := TVirtualData<TArray<String>>.Create(MyStrings);
end;

procedure TFormArray.BRecordClick(Sender: TObject);
begin
  SetLength(MyData, 10);
  FillMyData(MyData);

  TeeGrid1.Data := TVirtualData<TArray<TPerson>>.Create(MyData);
end;

procedure TFormArray.BTObjectClick(Sender: TObject);
begin
  SetLength(MyCars, 10);
  FillMyData(MyCars);

  TeeGrid1.Data := TVirtualData<TArray<TCar>>.Create(MyCars);
end;

procedure TFormArray.FormCreate(Sender: TObject);
begin
  // Start with array of records
  BRecordClick(Self);
  
  // Enable multi-line text in cells
  TeeGrid1.Rows.Height.Automatic := True;
end;

end.

Key Concepts

Automatic Column Generation

TeeGrid uses RTTI to automatically:

• Detect all public fields and published properties
• Create columns with appropriate editors (string, numeric, date, boolean)
• Handle nested records (creates sub-columns)
• Format data appropriately (dates, floats, etc.)

Sub-Records

Nested records are automatically expanded:

TAddress = record
  Street: String;
  Number: Integer;
end;

TPerson = record
  Name: String;
  Address: TAddress;  // Creates "Address.Street" and "Address.Number" columns
end;

Data Formatting

// Format float columns
TeeGrid1.Columns['Height'].DataFormat.Float := '0.##';

// Format date columns
TeeGrid1.Columns['BirthDate'].DataFormat.DateTime := 'mm-dd-yyyy';

Features Demonstrated

• Array of simple types (Integer, Single, String)
• Array of records with nested structures
• Array of object instances
• Automatic column generation via RTTI
• Custom data formatting

Next Steps

• Learn about List Binding for TList<T>
• Explore Custom Editors for cell editing
• See Custom Sorting to enable sorting

Related Examples

• List Binding
• Dataset Binding
• Virtual Mode