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org.apache.commons.beanutils
Class BeanToPropertyValueTransformer  

java.lang.Object
  org.apache.commons.beanutils.BeanToPropertyValueTransformer

All Implemented Interfaces:

org.apache.commons.collections.Transformer

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public class BeanToPropertyValueTransformer

extends java.lang.Object

implements org.apache.commons.collections.Transformer

Transformer that outputs a property value.

An implementation of org.apache.commons.collections.Transformer that transforms the object provided by returning the value of a specified property of the object. The constructor for BeanToPropertyValueTransformer requires the name of the property that will be used in the transformation. The property can be a simple, nested, indexed, or mapped property as defined by org.apache.commons.beanutils.PropertyUtils. If any object in the property path specified by propertyName is null then the outcome is based on the value of the ignoreNull attribute.

A typical usage might look like:

 // create the transformer
 BeanToPropertyValueTransformer transformer = new BeanToPropertyValueTransformer( "person.address.city" );

 // transform the Collection
 Collection peoplesCities = CollectionUtils.collect( peopleCollection, transformer );
 

This would take a Collection of person objects and return a Collection of objects which represents the cities in which each person lived. Assuming...

• The top level object in the peeopleCollection is an object which represents a person.
• The person object has a getAddress() method which returns an object which represents a person's address.
• The address object has a getCity() method which returns an object which represents the city in which a person lives.

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Field Summary
private  boolean	ignoreNull           Should null objects on the property path throw an IllegalArgumentException?
private  org.apache.commons.logging.Log	log           For logging.
private  java.lang.String	propertyName           The name of the property that will be used in the transformation of the object.

 

Constructor Summary

BeanToPropertyValueTransformer(java.lang.String propertyName)           Constructs a Transformer which does not ignore nulls.

BeanToPropertyValueTransformer(java.lang.String propertyName, boolean ignoreNull)           Constructs a Transformer and sets ignoreNull.

 

Method Summary
java.lang.String	getPropertyName()           Returns the name of the property that will be used in the transformation of the bean.
boolean	isIgnoreNull()           Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
java.lang.Object	transform(java.lang.Object object)           Returns the value of the property named in the transformer's constructor for the object provided.

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

log

private final org.apache.commons.logging.Log log

For logging.

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propertyName

private java.lang.String propertyName

The name of the property that will be used in the transformation of the object.

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ignoreNull

private boolean ignoreNull

Should null objects on the property path throw an IllegalArgumentException?

Determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.

Constructor Detail

BeanToPropertyValueTransformer

public BeanToPropertyValueTransformer(java.lang.String propertyName)

Constructs a Transformer which does not ignore nulls. Constructor which takes the name of the property that will be used in the transformation and assumes ignoreNull to be false.

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BeanToPropertyValueTransformer

public BeanToPropertyValueTransformer(java.lang.String propertyName,
                                      boolean ignoreNull)

Constructs a Transformer and sets ignoreNull. Constructor which takes the name of the property that will be used in the transformation and a boolean which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Method Detail

transform

public java.lang.Object transform(java.lang.Object object)

Returns the value of the property named in the transformer's constructor for the object provided. If any object in the property path leading up to the target property is null then the outcome will be based on the value of the ignoreNull attribute. By default, ignoreNull is false and would result in an IllegalArgumentException if an object in the property path leading up to the target property is null.

Specified by:

transform in interface org.apache.commons.collections.Transformer

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getPropertyName

public java.lang.String getPropertyName()

Returns the name of the property that will be used in the transformation of the bean.

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isIgnoreNull

public boolean isIgnoreNull()

Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.

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