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Subject: RE: bug in javabeans setter (ComplexBeanProbe.java)?
Date: Thu, 31 Aug 2006 14:34:07 -0400
Message-ID: <8A0052EB3E72CF45B236A55DA0E3B4371A8BE8@MG0PEXC01.aqrcapital.com>
Thread-Topic: bug in javabeans setter (ComplexBeanProbe.java)?
Thread-Index: AcbLl6ato7P/B0PvRfW0lWqNyPRPKwAEu0bgACzgvoAAKIo18AAJX8EQAACqUWA=
From: "Adam Klein" <Adam.Klein@aqr.com>
To: <user-java@ibatis.apache.org>

I don't think solves it.  Check out the setObject(...) function in
ComplexBeanProbe.java, listed below, followed by my analysis. =20

public void setObject(Object object, String name, Object value) {
(1) if (name.indexOf('.') > -1) {
      StringTokenizer parser =3D new StringTokenizer(name, ".");
(2)   String property =3D parser.nextToken();
(3)   Object child =3D object;
(4)   while (parser.hasMoreTokens()) {
(5)     Class type =3D getPropertyTypeForSetter(child, property);
(6)     Object parent =3D child;
(7)     child =3D getProperty(parent, property);
(8)     if (child =3D=3D null) {
(9)       if (value =3D=3D null) {
            return; // don't instantiate child path if value is null
          } else {
            try {
(10)          child =3D type.newInstance();
(11)          setObject(parent, property, child);
            } catch (Exception e) {
			...
            }
          }
        }
        property =3D parser.nextToken();
      }
(13)  setProperty(child, property, value);
    } else {
      setProperty(object, name, value);
    }
  }

Here is what happens.  Ibatis calls:

	setObject(myClass, "myHashMap.key1", "value1")

with myClass =3D new MyClass(), myHashMap =3D=3D null, and then:

1.  true condition, "myHashMap.key1" has "." in it
2.  property =3D "myHashMap"=09
3.  child =3D myClass
4.  true condition, parser has more tokens
5.  type =3D "java.util.HashMap"
6.  parent =3D myClass
7.  child =3D myHashMap
8.  true condition, child (myHashMap) IS null
9.  false condition, value =3D=3D "value1", not null
10. child =3D new HashMap()
11. setObject(parent, property, child), ie, myClass.myHashMap =3D
COPY(child)
12. ...
13. setProperty(child, property, value), ie, child.key1 =3D "value1"

Note that child !=3D myHashMap at step 13 due to the setter's deep
copying.  Shouldn't it call setProperty(child, property, value) BEFORE
step 11?

Best,
  Adam

-----Original Message-----
From: Poitras Christian [mailto:Christian.Poitras@ircm.qc.ca]=20
Sent: Thursday, August 31, 2006 1:58 PM
To: user-java@ibatis.apache.org
Subject: RE: bug in javabeans setter (ComplexBeanProbe.java)?

Ok. I have an answer for this type of problem.

For your resultMap, iBatis will generate objects by calling the
following.
MyClass myClass =3D new MyClass(); <- iBatis calls instantiate but the
result is the same.
myClass.setMyDouble(value0);
myClass.setMyHashMap(new HashMap()); <- I think this is done.
myClass.getMyHashMap().setKey1(value1);
myClass.getMyHashMap().setKey2(value2);

To get pass your problem, you should change the setter with this.
	public void setMyHashMap(HashMap<String, String> h) {
            if (myHashMap =3D=3D null) {
			myHashMap =3D new HashMap<String,String>(h);
		}
		// create COPY of h
		if (h =3D=3D null)
            	myHashMap =3D null;
        	else {
            	myHashMap.clear();
	            myHashMap.putAll(h);
        	}
	}=09


-----Original Message-----
From: Adam Klein [mailto:Adam.Klein@aqr.com]=20
Sent: Thursday, 31 August 2006 09:32
To: user-java@ibatis.apache.org
Subject: RE: bug in javabeans setter (ComplexBeanProbe.java)?

My class looks like this:

Public class MyClass {
	HashMap<String,String> myHashMap;
	...		    =20

	MyClass() {
		// Uncomment to fix bad iBATIS behavior:
		// myHashMap =3D new HashMap<String,String>();
	}

	public void setMyHashMap(HashMap<String, String> h) {
		// create COPY of h
		if (h =3D=3D null)
            	myHashMap =3D null;
	      else if (myHashMap =3D=3D null)
            	myHashMap =3D new HashMap<String,String>(h);
        	else {
            	myHashMap.clear();
	            myHashMap.putAll(h);
        	}
	}=09

	Public HashMap<String, String> getMyHashMap() {
		return myHashMap;
	}
}


Now, if I use the result map below to generate a List of MyClass
objects, if myHashMap is not initialized to a non-null value in the
constructor (see commented-out line above), the value Key1 is not
assigned value1, because what happens is the code creates a new HashMap
object, say X, and before calling X.put(Key1, Value1), the code calls
setMyHashMap(X), and THEN it calls X.put(Key1, value1), but by this time
X no longer refers to the same object as myHashMap.

Hope this makes sense.

Regards,
  Adam


-----Original Message-----
From: Poitras Christian [mailto:Christian.Poitras@ircm.qc.ca]
Sent: Wednesday, August 30, 2006 2:01 PM
To: user-java@ibatis.apache.org
Subject: RE: bug in javabeans setter (ComplexBeanProbe.java)?

Can you post a copy of your setters?
I'm not sure what you're trying to ask or to do.

Christian

-----Original Message-----
From: Adam Klein [mailto:Adam.Klein@aqr.com]
Sent: Tuesday, 29 August 2006 16:41
To: user-java@ibatis.apache.org
Subject: bug in javabeans setter (ComplexBeanProbe.java)?

Apologies if this is posted twice, I don't think my first one made it.

I had implemented defensive copying on my javabean setter methods - ie,
so the value of the bean would be set to a COPY of the parameter  -
while the getter would return a direct reference.  Then, when I was
trying to set keys in an (uninitiailized) HashMap object to values like
this:

<resultMap id=3D"myResultMap" class=3D"MyClass">
	 <result property =3D myDouble 		column=3D"value0" />
       <result property =3D myHashMap.Key1 	column=3D"value1" />
       <result property =3D myHashMap.Key2 	column=3D"value2" />
</resultMap>

I got a very strange result: of the values in myHashMap, only the value
of myHashMap.key2 would be set; in general, the first key of an
(uninitialized) HashMap would never be assigned a value. I traced the
reason to the ComplexBeanProbe.java file, in the setObject method: it
called the method setObject(parent, property, child) prior to calling
setProperty(child, property, value), which meant that the parent.child
object no longer referenced the child object by the time the code
attempted to set values on the child object (due specifically to my
defensive copying).  If myHashMap is initialized to an empty HashMap
value on creation of MyClass, there are no problems.

The question is, is this just a symptom of defensive copying, or is this
a bug, where setProperty(child, property, value) should be called first?

Regards,
  Adam
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