Fluent JSON writer

TJSONWriter (unit JsonFlow.Writer) implements IJSONWriter. It converts an IJSONElement tree to a JSON string or stream.

Basic usage via the TJsonFlow facade

uses
  JsonFlow,
  JsonFlow.Interfaces,
  JsonFlow.Objects,
  JsonFlow.Arrays,
  JsonFlow.Value;

var
  LObj: IJSONObject;
  LJson: string;
begin
  LObj := TJSONObject.Create;
  LObj.Add('name', TJSONValueString.Create('Alice'));
  LObj.Add('age', TJSONValueInteger.Create(28));

  // Compact output
  LJson := TJsonFlow.Write.Write(LObj);
  // {"name":"Alice","age":28}

  // Indented (pretty-print)
  LJson := TJsonFlow.Write.Write(LObj, {AIdent=}True);
end;

Direct TJSONWriter usage

uses
  JsonFlow.Writer,
  JsonFlow.Interfaces;

var
  LWriter: TJSONWriter;
begin
  LWriter := TJSONWriter.Create;
  try
    LJson := LWriter.Write(LElement, {AIdent=}False);
  finally
    LWriter.Free;
  end;
end;

Constructor overloads

Constructor	Description
Create	Default format: en-US, ISO dates, . decimal separator
Create(AFormatSettings)	Custom format settings

Writing to a stream

LWriter.WriteToStream(LElement, LStream, {AIdent=}False);

Encodes the output as UTF-8.

Logging

LWriter.OnLog(
  procedure(const AMsg: string) begin WriteLn(AMsg); end
);

IJSONWriter interface

IJSONWriter = interface
  function Write(const AElement: IJSONElement; const AIdent: Boolean = False): String;
  procedure WriteToStream(const AElement: IJSONElement; AStream: TStream; const AIdent: Boolean = False);
  procedure OnLog(const ALogProc: TProc<String>);
end;

Building the element tree

Use the composition classes (JsonFlow.Objects, JsonFlow.Arrays, JsonFlow.Value) to build the tree before writing:

Class	Interface	Use for
TJSONObject	IJSONObject	JSON object {}
TJSONArray	IJSONArray	JSON array []
TJSONValueString	IJSONValue	string value
TJSONValueInteger	IJSONValue	integer value
TJSONValueFloat	IJSONValue	float value
TJSONValueBoolean	IJSONValue	boolean value
TJSONValueNull	IJSONValue	null value
TJSONValueDateTime	IJSONValue	ISO 8601 datetime

Alternative: use TJSONComposer

For building JSON programmatically without manually constructing the element tree, prefer TJSONComposer — it provides a fully fluent Add(...).BeginObject(...).EndObject API.