Package org.apache.commons.beanutils

Class BeanToPropertyValueTransformer

  • All Implemented Interfaces:
    org.apache.commons.collections.Transformer
    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.
    See Also:
    PropertyUtils, Transformer

    • Field Summary

      Fields 
      Modifier and Type Field Description
      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

      Constructors 
      Constructor Description
      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

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      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.

      • propertyName

        private final java.lang.String propertyName
        The name of the property that will be used in the transformation of the object.

      • ignoreNull

        private final 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.
        Parameters:
        propertyName - The name of the property that will be used in the transformation.
        Throws:
        java.lang.IllegalArgumentException - If the propertyName is null or empty.

      • 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.
        Parameters:
        propertyName - The name of the property that will be used in the transformation.
        ignoreNull - Determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
        Throws:
        java.lang.IllegalArgumentException - If the propertyName is null or empty.

    • Method Detail

      • getPropertyName

        public java.lang.String getPropertyName()
        Returns the name of the property that will be used in the transformation of the bean.
        Returns:
        The name of the property that will be used in the transformation of the bean.

      • 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.
        Returns:
        The flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

      • 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
        Parameters:
        object - The object to be transformed.
        Returns:
        The value of the property named in the transformer's constructor for the object provided.
        Throws:
        java.lang.IllegalArgumentException - If an IllegalAccessException, InvocationTargetException, or NoSuchMethodException is thrown when trying to access the property specified on the object provided. Or if an object in the property path provided is null and ignoreNull is set to false.