Deserialize JSON to object

JsonFlow uses RTTI to set public/published properties from a JSON object.

Using the TJsonFlow facade

uses
  JsonFlow;

// JSON string → new typed object (caller frees)
LUser := TJsonFlow.JsonToObject<TUser>(LJson);

// JSON string → existing object (in-place update; returns True on success)
TJsonFlow.JsonToObject(LJson, LExistingUser);

// JSON string → object list (generic)
LUserList := TJsonFlow.JsonToObjectList<TUser>(LJson);

// JSON string → object list (non-generic, type provided at runtime)
LList := TJsonFlow.JsonToObjectList(LJson, TUser);

Using TJSONSerializer directly

uses
  JsonFlow.Serializer,
  JsonFlow.Interfaces;

var
  LSerializer: TJSONSerializer;
begin
  LSerializer := TJSONSerializer.Create;
  try
    LSerializer.ToObject(LElement, LTargetObject);
  finally
    LSerializer.Free;
  end;
end;

ToObject populates LTargetObject from the IJSONElement and returns True on success.

Property mapping rules

1. JSON keys are matched to Delphi property names case-insensitively by default.
2. Use [JSONName('json_key')] to override the mapping (see Serializer attributes).
3. Use [JSONIgnore] to skip a property entirely.
4. Nested objects are recursively deserialized.
5. Dynamic arrays are deserialized from JSON arrays.

Handling unknown keys

Unknown JSON keys (keys without a matching Delphi property) are silently skipped.

Circular references

Enable detection via TJSONSerializerOptions.DetectCircularReferences. The CircularReferenceStrategy field controls behaviour:

The TCircularReferenceStrategy enum (unit JsonFlow.Serializer.CircularRef) has four values:

Value	Behaviour
crsException	Raises ECircularReferenceException (default)
crsNull	Serializes the back-reference as JSON null
crsReference	Emits a $ref string pointing to the first occurrence
crsIgnore	Silently skips the back-reference property

warning

The caller owns the object returned by JsonToObject<T>. Always wrap the result in a try/finally to avoid memory leaks.