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From Graham Leggett <minf...@sharp.fm>
Subject Subtle bug: torque and transactions
Date Mon, 01 Dec 2003 23:17:48 GMT
Hi all,

I have been trying to hunt down why attempts to set a field on a 
database row object have been ignored, and have uncovered why.

What I have is a table that is updated inside a transaction. First, a 
certain set of date rows in the table are set to null. Then, a second 
set of date rows are set to non null values - these two sets may 
intersect, and the dates may possibly be set to the same values they 
held at the start of the transaction.

The set field generated code for a date looks like this:

/**
  * Set the value of PostedDate
  */
public void setPostedDate(Date v )
{
     if (!ObjectUtils.equals(this.postedDate, v)) {
         this.postedDate = v;
         setModified(true);
     }
}

The first time the set field is called, this.postedDate is a Date, and v 
is null, so this.postedDate is set to v and setModified is made true. A 
save method is subsequently called - but as the transaction is not 
complete, the date is not immediately accessible.

The second time the set field is called, this.postedDate is a Date -> 
the original date *before* the start of the transaction, and not null. 
In this particular example, the Date is also *identical* to it's 
previous value. In this case, this.postedDate equals v, and the update 
is *not* run.

The transaction is completed, the database write happens, but as the 
second set field was ignored, the date field becomes what it was set to 
in the first set field - null - which is incorrect.

The fix seems to be to remove the ObjectUtils.equals() function, or to 
at least disable it while a transaction is in progress.

Is this the solution, or have I missed something?

Regards,
Graham
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