Delphi ActiveX

Check if Integer Exists at JSON Path

Demonstrates how to get an integer value at a JSON path, and how to check to see if it exists. Delphi ActiveX

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
json: TChilkatJsonObject;
path: WideString;
val: Integer;
wasFound: Integer;

begin
success := 0;

json := TChilkatJsonObject.Create(Self);

// First build simple JSON..
json.UpdateInt('test.abc',100);

json.EmitCompact := 0;
Memo1.Lines.Add(json.Emit());

// This is our JSON:
// {
//   "test": {
//     "abc": 100,
//   }
// }

path := 'test.notHere';

// The call to IntOf will return 0, because it's not present.
// But how do we know if it really was present, and the value was truly 0?
val := json.IntOf(path);
Memo1.Lines.Add('val = ' + IntToStr(val));

// We cannot use LastMethodSuccess because LastMethodSuccess only applies
// to methods that:
// - return a string
// - return a new Chilkat object, binary bytes, or a date/time.
// - returns a boolean status where 1 = success and 0 = failed.
// - returns an integer where failure is defined by a return value less than zero.
// The IntOf method fits none of these requirements, and therefore the LastMethodSuccess 
// is not a valid indicator..
wasFound := json.LastMethodSuccess;
Memo1.Lines.Add('wasFound = ' + IntToStr(Ord(wasFound)) + ' (not a valid indicator)');

// Instead, if the returned value is 0, we can double-check to see if the member was truly there..
if (val = 0) then
  begin
    wasFound := json.HasMember(path);
    Memo1.Lines.Add('wasFound = ' + IntToStr(Ord(wasFound)));
    if (wasFound = 1) then
      begin
        Memo1.Lines.Add('The value was present and is 0.');
      end
    else
      begin
        Memo1.Lines.Add('no member is present at test.notHere');
      end;
  end
else
  begin
    Memo1.Lines.Add('val = ' + IntToStr(val));
  end;

// Alternatively, you could check to see if the member exists beforehand..
if (json.HasMember(path) = 1) then
  begin
    Memo1.Lines.Add('val = ' + IntToStr(json.IntOf(path)));
  end
else
  begin
    Memo1.Lines.Add('no member at ' + path);
  end;
end;