BeanUtils.copyProperties convert Integer null to 0
Solution 1
Ok I've found this post
There is however a big difference between these two classes which I came across while using these classes: BeanUtils does an automatic type conversion and PropertyUtils does not.
For example: with BeanUtils you can set a double valued property by providing a String. BeanUtils will check the type of the property and convert the String into a double. With PropertyUtils you always have to provide a value object of the same type as the property, so in this example a double.
Automatic conversion is not necessary in this case, so better choice is PropertyUtils
class
Solution 2
Checking http://commons.apache.org/beanutils/api/org/apache/commons/beanutils/ConvertUtilsBean.html it indicates the default for Integer conversion is 0. This is because the destination type here is the primitive int or reference int and primitive int cannot be set to null.
You can override the converter for Integer and replace it with one whose default value is null.
UPDATE: Usage is
import org.apache.commons.beanutils.converters.IntegerConverter;
IntegerConverter converter = new IntegerConverter(null);
BeanUtilsBean beanUtilsBean = new BeanUtilsBean();
beanUtilsBean.getConvertUtils().register(converter, Integer.class);
Take a look at the source code for IntegerConverter - you set the default value in the constructor.
Related videos on Youtube
lukastymo
I'm a founder of Pragmatic Scala from scratch where you can learn functional programming in real-life projects, 6 weeks, 100% online. You can find more info about me here: linkedin twitter github web
Updated on June 04, 2022Comments
-
lukastymo almost 2 years
I noticed that BeanUtils.copyProperties(dest, src) has a strange side effect. All null
Integers
(probablyLong
,Date
etc. too) convert to 0 in both objects: source (sic!) and destination. Version: commons-beanutils-1.7.0javadoc:
Copy property values from the origin bean to the destination bean for all cases where the property names are the same.
For example:
class User { Integer age = null; // getters & setters } ... User userDest = new User(); User userSrc = new User(); BeanUtils.copyProperties(userDest, userSrc); System.out.println(userDest.getAge()); // 0 System.out.println(userSrc.getAge()); // 0
It can be very buggy that source object is actually modified. What is the best solution to make "real" copy of object with null value.
-
lukastymo over 12 yearsSounds like explanation. So what I need to do is replace/modify this Converter to return null - default value