REST.Json.TJson.ObjectToJsonString formatiert ausgeben?

[TiGü]

Also ich habe einen möglichen Ansatz, aber an einer Stelle brauche ich die Länge für ein Byte-Array und mache hier wieder ein ToString.
Da muss ich noch nach Alternativen suchen.

Delphi-Quellcode:

unit Format.JSON;

interface

uses
  System.SysUtils,
  System.Classes,
  System.JSON,
  System.JSON.Writers,
  System.JSON.Readers,
  System.JSON.Types;

type
  TJsonStringWriter = class(TJsonTextWriter)
  private
    FStringBuilder: TStringBuilder;
    FStringWriter: TStringWriter;
  public
    constructor Create;
    destructor Destroy; override;
    function ToString: string; override;
  end;

  TJsonStreamReader = class(TJsonTextReader)
  private
    FStreamReader: TStreamReader;
  public
    constructor Create(const AJsonObject: TJSONObject);
    destructor Destroy; override;
  end;

function JsonObjectToFormattedString(const AJsonObject: TJSONObject): string;

implementation

function JsonObjectToFormattedString(const AJsonObject: TJSONObject): string;
var
  JsonWriter: TJsonStringWriter;
  JsonReader : TJsonStreamReader;
begin
  JsonReader := TJsonStreamReader.Create(AJsonObject);
  try
    JsonWriter := TJsonStringWriter.Create;
    try
      JsonWriter.Formatting := TJsonFormatting.Indented;
      JsonWriter.WriteToken(JsonReader);
      Result := JsonWriter.ToString;
    finally
      JsonWriter.Free;
    end;
  finally
    JsonReader.Free;
  end;
end;

{ TJsonStringWriter }

constructor TJsonStringWriter.Create;
begin
  FStringBuilder := TStringBuilder.Create;
  FStringWriter := TStringWriter.Create(FStringBuilder);
  inherited Create(FStringWriter);
end;

destructor TJsonStringWriter.Destroy;
begin
  inherited Destroy;
  FStringWriter.Free;
  FStringBuilder.Free;
end;

function TJsonStringWriter.ToString: string;
begin
  Result := FStringBuilder.ToString;
end;

{ TJsonStreamReader }

constructor TJsonStreamReader.Create(const AJsonObject: TJSONObject);
var
  LBytes : TBytes;
  LStream : TStream;
  Len : Integer;
begin
  Len := AJsonObject.ToString.Length * 6; // <--- das ist dann natürlich Quatsch, vielleicht kann man die benötigte Länge auch anderes bestimmen.
  SetLength(LBytes, Len);
  Len := AJsonObject.ToBytes(LBytes, 0);
  SetLength(LBytes, Len);
  LStream := TMemoryStream.Create;
  LStream.WriteBuffer(LBytes, Length(LBytes));
  Assert(LStream.Size <> 0);

  LStream.Position := 0;
  FStreamReader := TStreamReader.Create(LStream);
  inherited Create(FStreamReader);
end;

destructor TJsonStreamReader.Destroy;
begin
  inherited;
  FStreamReader.Free;
end;

end.