Thank you Will, this is very cool. Much better than littering my form beans
with desribe methods.
mark n.
>From: Will Jaynes <[EMAIL PROTECTED]>
>Reply-To: "Struts Users Mailing List" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: Re: Custom describe() for use with BeanUtil.populate()
>Date: Tue, 21 May 2002 07:12:46 -0400
>
>You don't need your own describe method anymore. BeanUtils has added the
>capability to register conversion methods, to go from String to any
>arbitrary object. So for example, I have a MSCalendar object whose
>toString puts out mm/dd/yyyy format, and can take that same format in a
>constructor.
>
>The MSConverter (attached) is mostly copied from one of Craig's
>converters in the Commons BeanUtils package.
>
>public void testStuff()
> {
> Map map = null;
> int i;
>
> // Register converters that enable conversion of String properties
> // to a designated class. String->MSCalendar
> ConvertUtils.register(new MSCalendarConverter(),
> MSCalendar.class);
>
> EmployeeBean emp = new EmployeeBean();
> emp.setFirstName("Joe");
> emp.setLastName("Klein");
> emp.setBirthDate(new MSCalendar("1/1/1999"));
>
> EmployeeFormBean form = new EmployeeFormBean();
> try {
>
> // Copy all properties of an EmployeeBean to the corresponding
> // properties of an EmployeeFormBean.
> // This process uses the toString() method of each
> // property in EmployeeBean as the value to put into
> // the corresponding String property in the form.
> map = BeanUtils.describe(emp);
> BeanUtils.populate(form, map);
>
> // Conversely, copy all the properties from the form into
> // the corresponding properties of EmployeeBean, converting
> // from String to the taget object type.
> emp = new EmployeeBean();
> map = BeanUtils.describe(form);
> BeanUtils.populate(emp, map);
>
> } catch(Exception ex) {
> fail("failure:"+ex.getStackTrace());
> }
> }
>}
>
>DHS Struts wrote:
>>I was wondering if anyone had a custom describe method they would be
>>willing to share as an example of what Ted Husted describes in his
>>"Struts Catalog" in the 'Use a "populate" utility to exchange data with
>>value objects' section?
>>
>>I understand the basic concept of needing to write my own describe() for
>>those beans that have Date attributes (because the BeanUtil.populate()
>>can't handle them), but I am not having much luck getting it to work.
>>
>>If you have some code and are willing to share I would appreciate it.
>>Also, if you would like to see what I have attempted I can post that
>>here as well.
>>
>>Thank you in advance,
>>
>>mark n.
>>
>>_________________________________________________________________
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>>
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>
>
>package edu.umich.umms.beanutils;
>import java.sql.Date;
>import org.apache.commons.beanutils.ConversionException;
>import org.apache.commons.beanutils.Converter;
>
>
>/**
> * <p>Standard {@link Converter} implementation that converts an incoming
> * String into a <code>edu.umich.umms.util.MSCalendar</code> object,
>optionally using a
> * default value or throwing a {@link ConversionException} if a conversion
> * error occurs.</p>
> *
> */
>
>public final class MSCalendarConverter implements Converter {
>
>
> // -----------------------------------------------------------
>Constructors
>
>
> /**
> * Create a {@link Converter} that will throw a {@link
>ConversionException}
> * if a conversion error occurs.
> */
> public MSCalendarConverter() {
>
> this(null);
>
> }
>
>
> /**
> * Create a {@link Converter} that will return the specified default
>value
> * if a conversion error occurs.
> *
> * @param defaultValue The default value to be returned
> */
> public MSCalendarConverter(Object defaultValue) {
>
> this.defaultValue = defaultValue;
>
> }
>
>
> // ----------------------------------------------------- Instance
>Variables
>
>
> /**
> * The default value specified to our Constructor, if any.
> */
> private Object defaultValue = null;
>
>
> // --------------------------------------------------------- Public
>Methods
>
>
> /**
> * Convert the specified input object into an output object of the
> * specified type.
> *
> * @param type Data type to which this value should be converted
> * @param value The input value to be converted
> *
> * @exception ConversionException if conversion cannot be performed
> * successfully
> */
> public Object convert(Class type, Object value) {
>
> if (value == null) {
> if (defaultValue != null) {
> return (defaultValue);
> } else {
> throw new ConversionException("No value specified");
> }
> }
>
> try {
> return new edu.umich.umms.util.MSCalendar((String) value);
>// return (Date.valueOf((String) value));
> } catch (Exception e) {
> if (defaultValue != null) {
> return (defaultValue);
> } else {
> throw new ConversionException(e);
> }
> }
>
> }
>
>
>}
>
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