Delphi DLL

Get the Root of a JSON Document

See more JSON Examples

Demonstrates how to get back to the JSON root object from anywhere in the JSON document. This example uses the following JSON document:

{
  "flower": "tulip",
  "abc":
    {
    "x": [
       { "a" : 1 },
       { "b1" : 100, "b2" : 200 },
       { "c" : 3 }
    ],
    "y": 200,
    "z": 200
    }
}

Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
json: HCkJsonObject;
jsonStr: PWideChar;
abcObj: HCkJsonObject;
xArray: HCkJsonArray;
bObj: HCkJsonObject;
docRoot: HCkJsonObject;

begin
success := False;

json := CkJsonObject_Create();

jsonStr := '{"flower": "tulip","abc":{"x": [{ "a" : 1 },{ "b1" : 100, "b2" : 200 },{ "c" : 3 }],"y": 200,"z": 200}}';

success := CkJsonObject_Load(json,jsonStr);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJsonObject__lastErrorText(json));
    Exit;
  end;

// Get the "abc" object.
abcObj := CkJsonObject_Create();
success := CkJsonObject_ObjectOf2(json,'abc',abcObj);
if (success = False) then
  begin
    Memo1.Lines.Add(CkJsonObject__lastErrorText(json));
    Exit;
  end;

// Side note: The JSON of a sub-part of the document can be emitted from any JSON object:
CkJsonObject_putEmitCompact(abcObj,False);
Memo1.Lines.Add(CkJsonObject__emit(abcObj));

// Navigate to the "x" array
xArray := CkJsonArray_Create();
CkJsonObject_ArrayOf2(abcObj,'x',xArray);

// Navigate to the 2nd object contained within the array.  This contains members b1 and b2
bObj := CkJsonObject_Create();
CkJsonArray_ObjectAt2(xArray,1,bObj);

// Show that we're at "b1/b2".
// The value of "b1" should be "200"
Memo1.Lines.Add('b2 = ' + IntToStr(CkJsonObject_IntOf(bObj,'b2')));

// Now go back to the JSON doc root:
docRoot := CkJsonObject_Create();
CkJsonObject_GetDocRoot2(bObj,docRoot);

// We'll skip the null check and assume it's non-null...

// Pretty-print the JSON doc from the root to show that this is indeed the root.
CkJsonObject_putEmitCompact(docRoot,False);
Memo1.Lines.Add(CkJsonObject__emit(docRoot));

CkJsonObject_Dispose(json);
CkJsonObject_Dispose(abcObj);
CkJsonArray_Dispose(xArray);
CkJsonObject_Dispose(bObj);
CkJsonObject_Dispose(docRoot);

end;