[英]Hibernate query by example (from Spring 3)
I've made my entity classes Adress
, Road
and County
. 我已经制作了我的实体课Adress
, Road
和County
。 A Road
is in a County
and an Adress
in on a Road
. 一个Road
是在County
和Adress
在上Road
。 I would like to list all the Adresses
in a County
. 我想列出一个County
所有Adresses
。 Therefore, in my AdressService
I say: 因此,在我的AdressService
我说:
public List<Adress> AllAdresses(County county) {
Adress adress = new Adress();
Road road = new Road();
road.setCounty(county);
adress.setRoad(road);
Example example = Example.create(adress);
return (List<Adress>) adressDAO.query(Adress.class, example);
}
In my AdressDAO
I have query(): 在我的AdressDAO
我有query():
public List query(Class<?> c, Example example) {
return getSession().createCriteria(c).add(example).setMaxResults(100).list();
}
This executes the following query on my database server: 这将在我的数据库服务器上执行以下查询:
select this_.AdressId as AdressId2_0_,
this_.Description as Descript3_2_0_,
this_.DescriptionShort as Descript4_2_0_,
this_.HouseLetter as HouseLetter2_0_,
this_.HouseNr as HouseNr2_0_,
this_.RoadId as RoadId2_0_
from tblAdress this_
where (this_.HouseNr=0)
limit 100
I had expected it to at least include SOME information about my entity County
, and an inner join with tblRoad
. 我原以为它至少包含了关于我的实体County
一些信息,以及一个带有tblRoad
的内部tblRoad
。 tblRoad
has a primary key roadId
, so I expected this_.roadId
to be joined with tblRoad.roadId
, and I expected tblRoad.countyId
to be set to the primary key of County
, that is countyId
. tblRoad
有一个主键roadId
,所以我希望this_.roadId
与tblRoad.roadId
,我希望将tblRoad.countyId
设置为County
的主键,即countyId
。
Why is the query in this example not built correctly when I use my own entity types? 当我使用自己的实体类型时,为什么这个例子中的查询没有正确构建? If I only use integers and strings, they work fine, but not entities. 如果我只使用整数和字符串,它们工作正常,但不是实体。 How do I make joins like this work with my own entities? 如何使这样的连接与我自己的实体一起工作?
From the Hibernate docs : 来自Hibernate文档 :
Version properties, identifiers and associations are ignored 版本属性,标识符和关联将被忽略
And that, as they say, is that. 而且,正如他们所说的那样。
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