protected override Expression VisitBinary(BinaryExpression expression) { if (expression.Type == typeof (bool) && expression.NodeType == ExpressionType.NotEqual) { var binaryExpression = expression.As<BinaryExpression>(); var locator = _mapping.JsonLocator(binaryExpression.Left); if (binaryExpression.Right.NodeType == ExpressionType.Constant && binaryExpression.Right.As<ConstantExpression>().Value == null) { var @where = new WhereFragment($"({locator}) IS NULL"); _callback(@where); } } return base.VisitBinary(expression); }