JsonToDataset

function DataSet.JsonToDataset(aJSON : string; Arg: TProc<TDataset>): String;
var
  JObj: TJSONArray;
  vConv : TCustomJSONDataSetAdapter;
  FmemoryDataset: TFDMemTable;
begin
  Result := aJSON;
  if (aJSON = EmptyStr) then
  begin
    Exit;
  end;
  FmemoryDataset:= TFDMemTable.Create(nil);
  JObj := TJSONObject.ParseJSONValue(aJSON) as TJSONArray;
  vConv := TCustomJSONDataSetAdapter.Create(Nil);
  try
    vConv.Dataset := FmemoryDataset;
    vConv.UpdateDataSet(JObj);
    if Assigned(Arg) then
       Arg(FmemoryDataset);
  finally
    vConv.Free;
    JObj.Free;
    FreeAndNil( FmemoryDataset );
  end;
 end;

function DataSet.JsonToMemoryDataset<TJsonString>(AJsonString: String; Arg: TProc<TDataset>): TDataset;

begin
 Result := self;
 JsonToDataset(AJsonString,Arg);
end;

function DataSet.TryField<T>(const aFieldName: String; Arg: T): Variant;
 var
   FField: TField;
begin
 try
  FFIeld:= FindField(aFieldName);
 finally
 if FField = nil then
    Result :=  Any.From(Arg).AsVariant
    else
    Result:= FField.Value;
 end;
 end;