Pascal (Lazarus/Delphi)

JSON: Access Array Values

See more JSON Examples

Demonstrates how to access values in a JSON array. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.JsonArray,
  Chilkat.JsonObject;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  json: TJsonObject;
  jsonStr: string;
  tagsArray: TJsonArray;
  arraySize: Integer;
  i: Integer;
  sValue: string;
  iValue: Integer;

begin
  success := False;

  json := TJsonObject.Create;

  jsonStr := '{ "id": 1, "name": "A green door", "tags": ["home", 22, "green"], "price": 125 }';

  success := json.Load(jsonStr);
  if (success <> True) then
    begin
      WriteLn(json.LastErrorText);
      Exit;
    end;

  //  Get the "tags" array, which contains "home", 22, "green"
  tagsArray := json.ArrayOf('tags');
  if (json.LastMethodSuccess = False) then
    begin
      WriteLn('tags member not found.');
      Exit;
    end;

  //  Get the value at each array index. 
  //  Output will be:
  //  [0] = home
  //  [0] as integer = 0
  //  [1] = 22
  //  [1] as integer = 22
  //  [2] = green
  //  [2] as integer = 0

  arraySize := tagsArray.Size;

  for i := 0 to arraySize - 1 do
    begin

      sValue := tagsArray.StringAt(i);

      WriteLn('[' + i + '] = ' + sValue);

      iValue := tagsArray.IntAt(i);
      WriteLn('[' + i + '] as integer = ' + iValue);

    end;

  tagsArray.Free;

  //  Note: The StringAt method returns the value as a string regardless of the type.

  //  The IntAt method returns the value as an integer.  If the value does not convert to 
  //  an integer, then 0 is returned.


  json.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.