Re: PersistentFieldMaxPerformanceImpl - can it work?

[Thomas Mahler]

Hi Oliver,

[EMAIL PROTECTED] wrote:

Hello,

I am using OJB 0.9.9 (from 31.01.03) I am trying to use the PersistentFieldMaxPerformanceImpl.
I have modified OJB.properties and my repository.xml accordingly.
It does not work (see below). I wonder how it could work.
Obviously someone has it working at his site.

I have a class Link with an embedded field Matrix

class Link {
Matrix transformation; // embedded
}

class Matrix {
long a1; }

When I stop the debugger at line 51 in file
PersistentNestedFieldMaxPerformanceImpl,
method getFieldRecursive()

46 String name = fieldname.substring(0, index);
47 Field field = c.getDeclaredField(name);
48 Class nestedClass = field.getType();
//
50 String nestedName = fieldname.substring(index + 1);
51 getFieldRecursive(nestedClass, nestedName); // throws a
NoSuchFieldException


fieldname: java.lang.String = "transformation->a1"
f: java.lang.reflect.Field = null
index: int = 14
name: java.lang.String = "transformation"
field: java.lang.reflect.Field = {java.lang.reflect.Field@664}
nestedClass: java.lang.Class = Matrix
nestedName: java.lang.String = ">a1"


Question 1:
nestedName= ">a1" is suspicious, isn't it? Shouldn't it
be index + PATH_TOKEN.length() in line 50? (That length is 2.)
How can it work for others?

I guess you are right!

Question 2:
Can't we include a JUnit test for that feature?  I can write it.
The only problem is ...

Sure, we should do this. Thanks for your offer to help.

Question 3: ... the PersistentFieldMaxPerformanceImpl can only
be configured globally, so if we switch to it, we will not be able
to test the other PersistentField-classes.  Should we change this?

IMO we should add the nested field functionality to all PersistentField Implementations.

Ideally we would have an AbstractPersistentField that contains all basic functionality (e.g. recursive lookup of fields, nested field access ...).
The concrete Implementations would only provide different field access strategies.

Unfortunately it's not that easy to separate these concerns...
But if someone is willing to spend some time on this topic I would really appreciate it.
As it is very important core functionality.

BTW 1: The error message you get is missleading, because the exception
due to the missing inner field is caught in the outermost
recursive call of getFieldRecursive, so the error messages are assembled
with either the complete or the outermost field name, in my case "transformation->a1" and "transformation", respectively. Since
this error can be provoked by the user even after this (potential)
bug is fixes, the message should be improved.

I agree!

BTW 2: if someone fixes this, could you please correct the package
names in the javadocs, too?  The "fieldaccess" is missing.

I hope we will have shorter update cycles of the website at our new home at db.apache.org...

The following fixes the problem for me.  Sorry for the linebreaks.
If someone just applies these changes to CVS, I will be happy.

I just checked it into CVS!

cheers,
Thomas

PersistentNestedFieldMaxPerformanceImpl.java

35c35
<      * @see
org.apache.ojb.broker.metadata.fieldaccess.PersistentFieldMaxPerformanceImpl
#getFieldRecursive(Class, String)
---

    * @see

org.apache.ojb.broker.metadata.PersistentFieldMaxPerformanceImpl#getFieldRec
ursive
(Class, String)
50c50
<                 String nestedName = fieldname.substring(index +
PATH_TOKEN.length());
---

               String nestedName = fieldname.substring(index + 1);

75c75
<      * @see
org.apache.ojb.broker.metadata.fieldaccess.PersistentField#get(Object)
---

    * @see org.apache.ojb.broker.metadata.PersistentField#get(Object)

83c83
<      * @see
org.apache.ojb.broker.metadata.fieldaccess.PersistentField#set(Object,
Object)
---

    * @see org.apache.ojb.broker.metadata.PersistentField#set(Object,

Object)
132c132
<             String nestedName = fieldName.substring(index +
PATH_TOKEN.length());
---

           String nestedName = fieldName.substring(index + 1);

167c167
<                 String nestedName = fieldName.substring(index +
PATH_TOKEN.length());
---

               String nestedName = fieldName.substring(index + 1);

Thank you for help,
	Olli


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