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From "Rashmi Dave" <rash...@persistent.co.in>
Subject RE: Selective Update of fields depending on values in object
Date Wed, 15 Feb 2006 15:50:52 GMT
Hi Jeff,

 

I started out thinking exactly the same and so did not see a problem with
the entire update. However, there are some fields in the table that are not
getting displayed. Now here, I need to fire a select, find out what the
current value is, and then put that value in the parameter object. Which
basically means an additional select per update.

 

I will write a custom update for the last login date.  Thanks a lot for your
help.

 

Regards

~Rashmi 

 

  _____  

From: Jeff Butler [mailto:jeffgbutler@gmail.com] 
Sent: Wednesday, February 15, 2006 9:10 PM
To: user-java@ibatis.apache.org
Subject: Re: Selective Update of fields depending on values in object

 

Hi Dave,

 

I understand the "last login date" requirement - I would write a custom
update for that requirement.

 

For the other, I've always taken a different stance on these kinds of
things.  It seems easier to me to update the whole record that do do the
dirty checking you would need to do to accomplish the selective update.  The
problem is this - how do you know what fields have changed?  If this is a
web app, then you would need to read the old record and do a field by field
check (or use some kind of JavaScript hack to set dirty flags).  If it's not
a web app, then its certainly easier to manage the state - but you would
still have to do the dirty check or set dirty flags somehow.  I've always
thought it was easier just to update the entire record. 

 

Just my thoughts - your experience may be different.

 

Jeff Butler



 

On 2/15/06, Rashmi Dave <rashmid@persistent.co.in> wrote: 

Hi Jeff,

 

I have a form - Update Profile of the User. Here, I would like to update
only those columns that have changed. 

 

Also, when my user logs in, I want to update only the Last_Login_date field
of the user table. This is why I need it. 

 

Hope this clarifies.

 

Regards

~Rashmi

 

  _____  

From: Jeff Butler [mailto: jeffgbutler@gmail.com] 
Sent: Wednesday, February 15, 2006 7:25 PM 
To: user-java@ibatis.apache.org
Subject: Re: Selective Update of fields depending on values in object

 

Hi Dave,

 

1. You don't need to regenerate the maps if all you're changing is NOT NULL
to NULL.  Abator doesn't care about the nullability of a column.  But
regenerating the maps shouldn't be a big issue anyway - Abator was designed
so you could run it repeatedly without losing anything extra you've added. 

 

2. You are correct that the update statement updates all columns.  You'll
need to write custom update statements if you want to update a subset of the
columns. 

 

I think it is unusual to do selective column updates if you are working with
anything close to a rich domain model - I've never had that requirement on
any of my projects.  That's why I didn't add support for it in Abator.  I
suppose it wouldn't be that difficult to add if there is a general feeling
that it's needed.  Does anyone else have any thoughts about this? 

 

Jeff Butler

 

On 2/15/06, Rashmi Dave < <mailto:rashmid@persistent.co.in>
rashmid@persistent.co.in> wrote: 

Hi All,

We are using Abator generated SQL Map configuration files. I have two
questions

1. It turns out that a column in a table that I thought is NOT NULL, should 
be a NULL column. I need to change the schema. Now do I need to re-generate
the SQL Maps again? (Please say I don't have to!!) Is there any information
regarding NULL/NOT NULL property stored?

2. The update query generated by Abator makes it compulsory for us to update

all columns in the table. What do I need to do to selectively update? Can I
somehow reuse the same update generated and avoid writing a different update
query per column? I hope this question isn't an obvious one. Kindly point me

to what feature I need to read the docs about if it is...

Thanks in advance.

Regards
~Rashmi

 

 


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