Copy specific fields by using BeanUtils.copyProperties?

Question

springframework.beans.BeanUtils is very useful to copy objects, and I use the "ignoreProperties" option frequently. However, sometimes I want to copy only specific objects (basically, the opposite of "ignore Properties"). Does anyone know how can I do that? Any help will be appreciated.

import org.springframework.beans.BeanUtils;

public class Sample {    
    public static void main(String[] args) {    
        DemoADto demoADto = new DemoADto();
        demoADto.setName("Name of Demo A");
        demoADto.setAddress("Address of Demo A");

        DemoBDto demoBDto = new DemoBDto();

        // This is "ignoreProperties" option
        // But I want to know how I can copy only name field by using BeanUtils or something.
        BeanUtils.copyProperties(demoADto, demoBDto, new String[] {"address"});

        System.out.println(demoBDto.getName());
        System.out.println(demoBDto.getAddress());    
    }    
}

public class DemoADto {    
    private String name;    
    private String address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }    
}

public class DemoBDto {    
    private String name;    
    private String address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }    
}

score 65 · Accepted Answer · edited Mar 28 '18 at 16:03

65

You can use the BeanWrapper technology. Here's a sample implementation:

public static void copyProperties(Object src, Object trg, Iterable<String> props) {

    BeanWrapper srcWrap = PropertyAccessorFactory.forBeanPropertyAccess(src);
    BeanWrapper trgWrap = PropertyAccessorFactory.forBeanPropertyAccess(trg);

    props.forEach(p -> trgWrap.setPropertyValue(p, srcWrap.getPropertyValue(p)));

}

Or, if you really, really want to use BeanUtils, here's a solution. Invert the logic, gather excludes by comparing the full property list with the includes:

public static void copyProperties2(Object src, Object trg, Set<String> props) {
    String[] excludedProperties = 
            Arrays.stream(BeanUtils.getPropertyDescriptors(src.getClass()))
                  .map(PropertyDescriptor::getName)
                  .filter(name -> !props.contains(name))
                  .toArray(String[]::new);

    BeanUtils.copyProperties(src, trg, excludedProperties);
}

edited Mar 28 '18 at 16:03

Fabio Bonfante

5,128
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answered Feb 22 '11 at 15:06

Sean Patrick Floyd

292,901
67
465
588

7

BeanWrapper technology is 25% faster. :) – arnabkaycee Sep 08 '15 at 05:02
Spring recommends using `PropertyAccessorFactory.forBeanPropertyAccess(Object)` instead. [source](http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/BeanWrapperImpl.html) – bheussler Feb 05 '16 at 21:11
how do you get Iterable properties ? – kiedysktos Dec 13 '16 at 16:14
@kiedysktos Iterable is an interface that is extended by Collection, so this method will accept any `Collection` – Sean Patrick Floyd Dec 13 '16 at 16:15
Tip on BeanWrapper: use trgWrap.setAutoGrowNestedPaths(true) to avoid NullValueInNestedPathException – gibaholms Mar 14 '17 at 01:14

score 3 · Answer 2 · edited Feb 22 '11 at 15:20

3

If you don't want to use Commons BeanUtils you can still use Spring by using the BeanWrapper.

You will have to manually loop through all the properties so you will want to make a static helper method.

You can always just copy what copyProperties is doing and adjust to your liking: http://tinyurl.com/BeanUtils-copyProperties

edited Feb 22 '11 at 15:20

Sean Patrick Floyd

292,901
67
465
588

answered Feb 22 '11 at 15:05

Adam Gent

47,843
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score 2 · Answer 3 · answered Feb 22 '11 at 15:01

2

Check this out: BeanPropertyCopyUtil.

Example:

copyProperties(user, systemUser, "first firstName", "last lastName");

You'll also need Apache Commons BeanUtils.

answered Feb 22 '11 at 15:01

eolith

1,366
10
14

This is not appropriate way to achieve this. What if your attribute name modified ? passing it as string is not better approach, rather fetch all the fields using Field[] fields = destination.getClass().getDeclaredFields(); And iterate over the fields for (Field field : fields){ //ur copy stuff here } – Sadanand Oct 23 '14 at 02:46
This is not working with child properties, let's say i wanted to ignore all properties with name "id". – Yogesh Prajapati Apr 16 '19 at 12:26

score 2 · Answer 4 · answered Sep 27 '21 at 12:22

2

beanUtils has an overloaded method wherein we can pass an array of fields that we want to ignore.

Eg.

String[] ignoreProperties= new String[]{"field1","field2"};

BeanUtils.copyProperties(a, b,ignoreProperties);

answered Sep 27 '21 at 12:22

AConsumer

2,461
2
25
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score 1 · Answer 5 · answered Jun 15 '15 at 07:16

1

You may use org.springframework.beans.BeanUtils.copyProperties(Object source, Object target, Class editable) throws BeansException

Ensure the target implements the interface editable which defines the properties which would be copied.

answered Jun 15 '15 at 07:16

Gautam Pal

51
2

score 0 · Answer 6 · answered May 19 '14 at 22:49

Here is an Example with Spring BeanUtils class:

public static void copyList(List sourceList,
        List targetList, Class targetType) {

    try {

        for (Object source : sourceList) {
            Object target = null;
            target = targetType.newInstance();
            BeanUtils.copyProperties(source, target);
            targetList.add(target);
        }

    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
}

Copy specific fields by using BeanUtils.copyProperties?

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