Ashok Mannolu Arunachalam, Sun Aug 08 2021 • java util fix spring

Fix: org.springframework.beans.BeanUtils: ignore null values on copying properties

I have recently encountered a situation where I had to copy properties between two domain objects like DTO vs VO.

Even though BeanUtils was helpful in most cases via copyProperties, in a particular case, I needed it to ignore the properties with null values getting copied and overwriting the values in the target.

I came across this implementation of the said method and understood it fully in order to make the change I needed.

java


import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import org.springframework.beans.FatalBeanException;
import org.springframework.util.Assert;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

@NoArgsConstructor(access = AccessLevel.PRIVATE)
public final class BeanUtils
	extends org.springframework.beans.BeanUtils {

    public static void copyNonNullProperties(
        Object source, Object target
    ) {
        Assert.notNull(source, "Source must not be null");
        Assert.notNull(target, "Target must not be null");
        Class<?> actualEditable = target.getClass();
        PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);
        for (PropertyDescriptor targetPd : targetPds) {
            if (targetPd.getWriteMethod() != null) {
                PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                if (
                    sourcePd != null
                    && sourcePd.getReadMethod() != null
                ) {
                    try {
                        Method readMethod = sourcePd.getReadMethod();
                        if (
                            !Modifier.isPublic(
                                readMethod.getDeclaringClass()
                                          .getModifiers())
                        ) {
                            readMethod.setAccessible(true);
                        }
                        Object value = readMethod.invoke(source);
                        // Ignore properties with null values.
                        if (value != null) {
                            Method writeMethod = targetPd.getWriteMethod();
                            if (
                                !Modifier.isPublic(
                                    writeMethod.getDeclaringClass()
                                                .getModifiers())
                            ) {
                                writeMethod.setAccessible(true);
                            }
                            writeMethod.invoke(target, value);
                        }
                    } catch (Throwable ex) {
                        throw new FatalBeanException(
                            "Could not copy properties from source to target", ex
                        );
                    }
                }
            }
        }
    }

}

To make it part of the BeanUtils, I have extended the said util class and added the above copyNonNullProperties method in our project. ^_^

Enjoy \O/

AshKeys

Fix: org.springframework.beans.BeanUtils: ignore null values on copying properties