from hibernate to mysql, default value mapping issue

Question

hibernate xml mapping file does not support default value. So when i try to create a column with default value in mysql, then i run the hibernate save() method without setting the column value. the default value cannot be generated.

i have done some search. according to this post: https://forums.hibernate.org/viewtopic.php?t=171&highlight=default+value&sid=84a014fd93dd9b680afc606f616ca4f6 it said hibernate does not support default value. we can use trigger instead.

Any way we can do this except trigger? and how can we do this by trigger

OK i try to do more search i find the answer:

ibernate does not support default values, you should either manager this using database triggers or assign default values in your domain.

But if i assign default values in my domain, said in constructer, do we have any drawback?

thx!

If you instead annotation instead, you could provide default values to the properties in the object. — billygoat
– billygoat, Commented Apr 17, 2011 at 9:54
thank you for ur reply, can i mix xml mapping with annotation? — EeE
– EeE, Commented Apr 17, 2011 at 9:56

vbence · Accepted Answer · 2014-04-15 06:42:54Z

3

I suggest using the constructor to set up the default state of your objects. Hibernate is an ORM. The basic philosophy is that you save your objects. Using default values at the DBMS end can undermine the whole concept, by making it possible to save objects in invalid states. (By making possible for field values to skip the setter methods).

In the other hand, when you instantiate an object its fields are already initiated (to null value or zero or empty string etc.) It would be impossible for Hibernate to guess whether you want to save the actual null or zero or you want to use the DB's default value instead.

When you're talking about default values in the DBMS level, i assume you think of primitive values. There is absolutely no drawback in initializing primitive fields on the Java side (inside the constructor or by declaration).

edited Apr 15, 2014 at 6:42

answered Apr 17, 2011 at 12:37

vbence

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