我是querydsl的新手，正在寻找一种基于过滤器附加/构建 predicate 的方法。您可以在示例中看到，如果筛选器中的某个字段没有值，则不应将其放入 predicate 中。
如果这样的事情是不可能的，那么最好的方法是什么呢？
例如，filter（getpaintingrequest）包含以下字段（filter中有更多字段，但并不重要）：

public class GetPaintingsRequest {
    private String author;
    private Integer style;
    private String paintingName;

    //.....getters and setters
}

所以在一个服务类中，我想像这样过滤绘画

public List<Painting> getFilteredPaintings(GetPaintingsRequest request) {

        QPainting painting = QPainting.painting;

        //predicate for all paintings that are not deleted and not sold
        Predicate query = painting.deleted.isFalse().and(painting.isSold.isFalse());

        if (!request.getAuthor().equals("")) {
            //append to existing predicate name of the author
            query.and.painting.autor.eq(request.getAuthor()); //obviously not working - just as an example what I want

        }

        if (!request.getPaintingName().equals("")) {
            //append to existing predicate painting name
            query.and.painting.paintingName.eq(request.getPaintingName()); //obviously not working - just as an example what I want
        }

        var paintingList = paintingRepository.findAll(query);

}