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optional vs nullable attributes [message #649109]

Mon, 17 January 2011 12:35

Daniel Le Berre
Messages: 82
Registered: July 2009

Member

Dear all,

I have a question regarding the meaning of the optional attribute that can be found on @Basic or relationship annotations and the nullable attribute that can be found in @Column and @JoinColumn annotations.

Isn't @Basic(optional=false) a hint for the JPA provider to make the underlying column not nullable?

I had the idea that the optional attribute on the object side was equivalent to the nullable attribute on the relational side.

Cheers,

Daniel

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Re: optional vs nullable attributes [message #649765 is a reply to message #649109]

Thu, 20 January 2011 09:47

James Sutherland
Messages: 1834
Registered: July 2009

Senior Member

The nullable attribute controls DDL generation (only).

The optional may be used for validation in the object model. Is has no affect of DDL generation Currently I do not think EclipseLink uses the optional for any validation.

James : Wiki : Book : Blog

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Re: optional vs nullable attributes [message #649773 is a reply to message #649765]

Thu, 20 January 2011 09:58

Daniel Le Berre
Messages: 82
Registered: July 2009

Member

Thanks for the answer James.

Wouldn't it make sense to take into account the optional flag into account in the DDL generation?

If I know in the object model that an attribute is mandatory, I should have a non nullable column in the table, right?

I try to use JPA annotations in such a way to define all my constraints on the object model, and to avoid database specific annotations by all means.

Changing the optional attribute value without seeing any effect on the DDL generation looks odd to me.

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