UseBean tag improvement

• Key: JELLY-120
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: dion gillard
• Reporter: Hans Gilde
• Component/s: core / taglib.core
• Affects Version/s: 1.0-beta-4
• Fix Version/s: 1.0-beta-4

Description

It's sort of hard to extend UseBean because it will try to set all the tag attributes as bean properties. You can remove an attribute from the map, but that's annoying because then your subclasses don't see it.

I added a couple of methods that let a subclass tell UseBean to ignore certain property names. So, those properties stay in the attribute map but don't cause errors in setting the bean.

This is the first step to a patch to clean up the Swing ComponentTag so that it fails properly when one misspells a bean property. As long as everyone agrees to this method of ignoring attributes that aren't bean properties.

Hans

##########################

Index: UseBeanTag.java

===================================================================

RCS file: /home/cvspublic/jakarta-commons/jelly/src/java/org/apache/commons/jelly/tags/core/UseBeanTag.java,v

retrieving revision 1.14

diff -u -r1.14 UseBeanTag.java

— UseBeanTag.java 24 Feb 2004 14:10:38 -0000 1.14

+++ UseBeanTag.java 20 Aug 2004 01:22:12 -0000

@@ -16,13 +16,15 @@

package org.apache.commons.jelly.tags.core;

import java.lang.reflect.InvocationTargetException;

+import java.util.HashMap;

+import java.util.HashSet;

import java.util.Map;

+import java.util.Set;

import org.apache.commons.beanutils.BeanUtils;

-

import org.apache.commons.jelly.JellyTagException;

-import org.apache.commons.jelly.MissingAttributeException;

import org.apache.commons.jelly.MapTagSupport;

+import org.apache.commons.jelly.MissingAttributeException;

import org.apache.commons.jelly.XMLOutput;

import org.apache.commons.jelly.impl.BeanSource;

@@ -50,6 +52,11 @@

/** the default class to use if no Class is specified */

private Class defaultClass;

+

+ /**a Set of Strings of property names to ignore (remove from the

+ * Map of attributes before passing to ConvertUtils)

+ */

+ private Set ignoreProperties;

public UseBeanTag() {

}

@@ -74,7 +81,8 @@

public void doTag(XMLOutput output) throws JellyTagException {

Map attributes = getAttributes();

String var = (String) attributes.get( "var" );

• Object classObject = attributes.remove( "class" );

+ Object classObject = attributes.get( "class" );

+ addIgnoreProperty("class");

try {

// this method could return null in derived classes

@@ -163,10 +171,15 @@

/**

• Sets the properties on the bean. Derived tags could implement some custom

• type conversion etc.

+ * <p/>

+ * This method ignores all property names in the Set returned by {@link #getIgnorePropertySet()}.

*/

protected void setBeanProperties(Object bean, Map attributes) throws JellyTagException {

+ Map attrsToUse = new HashMap(attributes);

+ attrsToUse.keySet().removeAll(getIgnorePropertySet());

+

try { - BeanUtils.populate(bean, attributes); + BeanUtils.populate(bean, attrsToUse); } catch (IllegalAccessException e) { throw new JellyTagException("could not set the properties of the bean",e); } catch (InvocationTargetException e) {

@@ -196,5 +209,26 @@

*/

protected Class getDefaultClass() { return defaultClass; + }

+

+ /** Adds a name to the Set of property names that will be skipped when setting

+ * bean properties. In other words, names added here won't be set into the bean

+ * if they're present in the attribute Map.

+ * @param name

+ */

+ protected void addIgnoreProperty(String name) { + getIgnorePropertySet().add(name); + }

+

+ /** Gets the Set of property names that should be ignored when setting the

+ * properties of the bean.

+ * @return

+ */

+ protected Set getIgnorePropertySet() {

+ if (ignoreProperties == null) { + ignoreProperties = new HashSet(); + }

+

+ return ignoreProperties;

}

}

Comments

[dion gillard]

I think this should be done for beta4

[Hans Gilde]

cool, how about this one. It adds an option to ignore unknown properties. I figured that subclasses of UseBean might want it to ignore unknown properties.

The thing is that to make this work, I had to change from BeanUtils.populate(), to BeanUtils.copyProperties(). I think that this is a good change but it needs unit tests, which I'll do.

[dion gillard]

I'm just in the process of adding test cases for the addIgnoredProperty code.

[dion gillard]

Hans, could you re-do the patch for unknown properties off the latest code?

That'd be great.

It'd be even better if you added tests to the new test cases I've created.

Thanks

[Hans Gilde]

Let me know if you think of more test cases. There are none with arrays or collections...

[dion gillard]

I made minor changes to the patch:

• use Properties instead of Props
• remove use of Jelly junit taglib, and put asserts back in the code
• added license for new file

[Hans Gilde]

Thanks. I meant to add this comment to validateBeanProperties.

/** If {@link #isIgnoreUnknownProps()} returns true, make sure that

• every non-ignored ({@see #addIgnoreProperty(String)}) property
• matches a writable property on the target bean.
• @param bean
• @param attributes
• @throws JellyTagException
  */