如何只修改spring数据jpa中的实体的一部分？

Question

How do I modify only part of an entity in Spring Data JPA?

Here is my code.

public void modifyDrawing(Long no, String name, Double lat, Double lon, String physicalName, String desc) {
   Drawing drawing = drawingRepository.findById(no)
       .orElseThrow(NoSuchElementException::new);

   drawing.setName(name);
   drawing.setLat(lat);
   drawing.setLon(lon);
   drawing.setPhysicalName(physicalName);
   drawing.setDesc(desc);
   drawingRepository.save(drawing);
}

At this time, if lat and lon are null, I want to keep the values without changing them. I am wondering how to update the entity value using only non-null parameter values.

Answer 1

You should add an if check to make sure the latitude/longitude are not null before calling their setters.

public void modifyDrawing(Long no, String name, Double lat, Double lon, String physicalName, String desc) {
    Drawing drawing = drawingRepository.findById(no)
        .orElseThrow(NoSuchElementException::new);

    drawing.setName(name);
    if (lat != null) {
        drawing.setLat(lat);
    }
    if (lon != null) {
        drawing.setLon(lon);
    }
    drawing.setPhysicalName(physicalName);
    drawing.setDesc(desc);
    drawingRepository.save(drawing);
}