How to ignore null values using springframework BeanUtils copyProperties?

Question

I would like to know how to copy the properties from an Object Source to an Object Dest ignoring null values using Spring Framework.

I actually use Apache beanutils, with this code

    beanUtils.setExcludeNulls(true);
    beanUtils.copyProperties(dest, source);

to do it. But now i need to use Spring.

Any help?

Thx a lot

Can you not include BeanUtils as part of your Spring project class path? I don't think Spring's BeanUtils work this way. — Jason Lowenthal, Nov 02 '13 at 00:37

score 86 · Accepted Answer · edited Nov 25 '19 at 12:00

86

You can create your own method to copy properties while ignoring null values.

public static String[] getNullPropertyNames (Object source) {
    final BeanWrapper src = new BeanWrapperImpl(source);
    java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();

    Set<String> emptyNames = new HashSet<String>();
    for(java.beans.PropertyDescriptor pd : pds) {
        Object srcValue = src.getPropertyValue(pd.getName());
        if (srcValue == null) emptyNames.add(pd.getName());
    }

    String[] result = new String[emptyNames.size()];
    return emptyNames.toArray(result);
}

// then use Spring BeanUtils to copy and ignore null using our function
public static void myCopyProperties(Object src, Object target) {
    BeanUtils.copyProperties(src, target, getNullPropertyNames(src));
}

edited Nov 25 '19 at 12:00

mohkamfer

435
3
12

answered Nov 02 '13 at 04:47

Alfred Xiao

1,758
15
16

This is a very good solution for it. I hoped that the Framework had already scheduled a way that will take care of that, but this will work perfectly. thanks – Fingolricks Nov 04 '13 at 03:14
I did the same. I included these methods in a new class with some other custom implementations. My new class extends BeanUtils class so that I can add additional features and functionalities. – yuva Nov 05 '15 at 09:01
There's typo in call sig of myCopyProps method... extra comma after Object – Adam Hughes Feb 11 '16 at 14:25

score 55 · Answer 2 · edited May 23 '17 at 11:46

Java 8 version of getNullPropertyNames method from alfredx's post:

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);
}

score 8 · Answer 3 · answered Oct 06 '18 at 18:11

I advise you to use ModelMapper.

This is a sample code that solves your doubt.

      ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration().setSkipNullEnabled(true).setMatchingStrategy(MatchingStrategies.STRICT);

      Company a = new Company();
      a.setId(123l);
      Company b = new Company();
      b.setId(456l);
      b.setName("ABC");

      modelMapper.map(a, b);

      System.out.println("->" + b.getName());

It should print the B value. But if you set the "A" name, the result is a print of "A" value.

The secret is changing the value of SkipNullEnabled to true.

ModelMapper

ModelMapper MVN

Its not working,, I tried. Its replacing the values if it find otherwise it creates new. — Abdul, Apr 06 '19 at 05:03

score 5 · Answer 4 · edited Jan 01 '19 at 11:48

SpringBeans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean id="source" class="com.core.HelloWorld">
        <property name="name" value="Source" />
        <property name="gender" value="Male" />
    </bean>

    <bean id="target" class="com.core.HelloWorld">
        <property name="name" value="Target" />
    </bean>

</beans>

Create a java Bean,

public class HelloWorld {
    private String name;
    private String gender;

    public void printHello() {
        System.out.println("Spring 3 : Hello ! " + name + "    -> gender      -> " + gender);
    }

    //Getters and Setters
}

Create Main Class to test

public class App {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("SpringBeans.xml");

        HelloWorld source = (HelloWorld) context.getBean("source");
        HelloWorld target = (HelloWorld) context.getBean("target");

        String[] nullPropertyNames = getNullPropertyNames(target);
        BeanUtils.copyProperties(target,source,nullPropertyNames);
        source.printHello();
    }

    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);
    }
}

score 1 · Answer 5 · answered Sep 19 '19 at 22:40

1

public static List<String> getNullProperties(Object source) {
    final BeanWrapper wrappedSource = new BeanWrapperImpl(source);
    return Stream.of(wrappedSource.getPropertyDescriptors())
        .map(FeatureDescriptor::getName)
        .filter(propertyName -> Objects.isNull(wrappedSource.getPropertyValue(propertyName)))
        .collect(Collectors.toList());

answered Sep 19 '19 at 22:40

Kamaljit Sidhu

19
1

2

It would probably be best to add some form of explanation to your answer; that will improve its quality and make it more likely to get upvotes :) – Das_Geek Sep 19 '19 at 23:01
1

...especially as it's 99% similar to a answer posted above (4 years earlier): https://stackoverflow.com/a/32066155 – maxxyme Dec 15 '21 at 09:53

score 1 · Answer 6 · answered Nov 27 '19 at 07:52

A better solution based on Pawel Kaczorowski's answer:

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

For example, if we have a DTO:

class FooDTO {
    private String a;
    public String getA() { ... };
    public String getB();
}

Other answers will throw exceptions on this special case.

How to ignore null values using springframework BeanUtils copyProperties?

6 Answers6

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