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From Jarek Gawor <>
Subject Re: jpa blueprint ns handler question
Date Fri, 05 Nov 2010 20:16:20 GMT
On Fri, Nov 5, 2010 at 6:08 AM, Timothy Ward <> wrote:
> To clarify, the aim when designing this function was to make consuming persistence units
and contexts as simple as possible - hence trying to make sure that it could be expressed
as a single element.
> The primary injection mechanism people use is by setters, which in blueprint would be
something like:
> <property name="foo" ref="bar"/>
> In order to get JPA to be similarly concise, and to avoid breaking the existing validation
requirements of Blueprint, we came up with the <unit/> and <context/> tags, which
contain the information from an @PersistenceContext and @PersistenceUnit annotation.
> The decision was made that:
> <property name="emf" type="javax.persistence.EntityManagerFactory">
>   <jpa:unit unitname="myUnit"/>
> </property>
> was significantly less usable than:
> <jpa:unit property="emf" unitname="myUnit"/>

I disagree. To me the following is much clearer:

<property name="emf">
  <jpa:unit unitname="myUnit">

And this syntax is consistent with rest of the blueprint syntax, i.e.
how you would inject a bean as a property or argument. The <jpa:unit/>
and <jpa:context/> provide a specific object just like a <bean/> or
<reference/>, etc. and should be handled in the same way, IMHO.


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