How to parse a JSON string in Delphi?

Question

How can I parse the JSON string

{"data":{"results":[{"Branch":"ACCT590003"}]}}

using the TJSONObject object? I want to get the ACCT590003 value from this string.

Answer 1

uses
  SysUtils,
  DBXJSON;

type
  TProcessJSONString = TProc<TJSONString>;

procedure DoJSONObject(o: TJSONObject; Process: TProcessJSONString); forward;

procedure DoJSONArray(o: TJSONArray; Process: TProcessJSONString);
var i: integer;
    v: TJSONValue;
begin
  for i := 0 to o.Size - 1 do begin
    v := o.Get(i);
    if v is TJSONObject then
      DoJSONObject(v as TJSONObject, Process);
  end;
end;

procedure DoJSONObject(o: TJSONObject; Process: TProcessJSONString);
var i: integer;
    p: TJSONPair;
begin
  for i := 0 to o.Size - 1 do begin
    p := o.Get(i);
    Process(p.JsonString);
    if p.JsonValue is TJSONObject then
      DoJSONObject(p.JsonValue as TJSONObject, Process)
    else if p.JsonValue is TJSONArray then
      DoJSONArray(p.JsonValue as TJSONArray, Process)
    else if p.JsonValue is TJSONString then
      Process(p.JsonValue as TJSONString);
  end;
end;

var o: TJSONObject;
begin
  o := TJSONObject.ParseJSONValue('{"data":{"results":[{"Branch":"ACCT590003"}]}}') as TJSONObject;
  try
    DoJSONObject(o,
      procedure (o: TJSONString)
      begin
        WriteLn(o.ToString);
      end
    );
  finally
    o.Free;
  end;
  ReadLn;
end.