Read data from another MDIChild form

Spread the love

Read data from another MDIChild form

type
  TMDIChildForm = class(TForm)
    Edit1: TEdit;
  private
    { Private declarations }
    procedure ReadDataFromOtherMDIChildForm;
  end;

var
  MDIChildForm: TMDIChildForm;

implementation

{$R *.DFM}

uses
  MainForm;
  // Property FormStyle of this form is fsMDIForm

procedure TMDIChildForm.ReadDataFromOtherMDIChildForm;
var
  i: Integer;
  DataFromOtherForm: string;
begin
  // Suppose you have created three different MDIChild forms of the same type,
  // each with the following caption: "aaa", "bbb", "ccc".
  // You are currently on form with caption "aaa" and want to read data
  // contained on form with caption "ccc".
  // You can find here the code, you have to use the "as" clause and
  // properties MDIChildCount and MDIChildren:

  // First you have to find where the form "ccc" is in memory;
  for i := 0 to MDIForm.MDIChildCount - 1 do
  begin
    if (Pos('ccc', MDIForm.MDIChildren[i].Caption)  0) then
      Break;
  end;
  // Check to see if the form is the last on MDIChildren array and
  // correct I variable
  if (i = MDIChildCount) then Dec(i);
  // I variable contains the index of the form with caption 'ccc'

  if (Pos('ccc', MDIForm.MDIChildren[i].Caption)  0) then
  begin
    // If the form with caption 'ccc' exists then you access data and show it
    // The following line of code is very interesting, look at the "as" clause,
    // if you have different types of MDIChild forms, you simply change
    // the type of form after the "as" clause
    // The data you want is contained on Edit1.Text
    with (MDIForm.MDIChildren[I] as TMDIChildForm).Edit1 do
      DataFromOtherForm := Text;
    ShowMessage(DataFromOtherForm);
  end;
end;