除了在 spring 引導中執行空檢查之外，還有更有效的方法來處理補丁請求更新嗎？

Question

除了最初執行空檢查之外，還有更好的更新方法嗎？

@PatchMapping("/base/uri/{id}")
public void updateModel(@Valid @RequestBody Model newModel, @Pathvariable Long id) {
    modelRepository.findById(id).map(model -> {
        if (newModel.getParam1() != null) model.setParam1(newModel.getParam1());
        if (newModel.getParam2() != null) model.setParam1(newModel.getParam2());
        if (newModel.getParam3() != null) model.setParam1(newModel.getParam3());
        if (newModel.getParam4() != null) model.setParam1(newModel.getParam4());
        ...
        modelRespository.save(model);
    }).orElseThrow(() -> MyNotFoundException());
}

Answer 1

您可以使用 spring 框架的BeanUtils添加要忽略的屬性（在這種情況下是 null ），如下所示：

import java.beans.FeatureDescriptor;
import java.util.stream.Stream;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;

@PatchMapping("/base/uri/{id}")
public void updateModel(@Valid @RequestBody Model newModel, @Pathvariable Long id) {
modelRepository.findById(id).map(model -> {
       String[] nulls = getNullPropertyNames(newModel);
       // copy the newModel into model 
       // avoiding the properties listed in "nulls"
       BeanUtils.copyProperties(newModel, model, nulls);
       modelRespository.save(model);
   }).orElseThrow(() -> MyNotFoundException());
}

public static String[] getNullPropertyNames(Object source) {
    final BeanWrapper wrappedSource = new BeanWrapperImpl(source);
    return Stream.of(wrappedSource.getPropertyDescriptors())
        .map(FeatureDescriptor::getName)
        .filter(propertyName -> wrappedSource.getPropertyValue(propertyName) == null)
        .toArray(String[]::new);
}