I have a spring-hibernate application which is failing to map an object properly: basically I have 2 domain objects, a Post and a User. The semantics are that every Post has 1 corresponding User.
The Post domain object looks roughly as follows:
class Post {
private int pId;
private String attribute;
...
private User user;
//getters and setters here
}
As you can see, Post contains a reference to User. When I load a Post object, I want to corresponding User object to be loaded (lazily - only when its needed).
My mapping looks as follows:
<class name="com...Post" table="post">
<id name="pId" column="PostId" />
<property name="attribute" column="Attribute" type="java.lang.String" />
<one-to-one name="User" fetch="join"
class="com...User"></one-to-one>
</class>
And of course I have a basic mapping for User set up.
As far as my table schema is concerned, I have a table called post with a foreign UserId which links to the user table.
I thought this setup should work, BUT when I load a page that forces the lazy loading of the User object, I notice the following Hiberate query being generated:
Select ... from post this_ left outer join user user2_ on this.PostId=user2_.UserId ...
Obviously this is wrong: it should be joining UserId from post with UserId from user, but instead its incorrectly joining PostId from post (its primary key) with UserId from user.
Any ideas? Thanks!
Update:
Thanks to a couple of the posts below I now realize that I should have been using a many-to-one mapping instead of a one-to-one. I changed the mapping under post to the following:
<many-to-one name="User" class="com...User" column="uId"/>
But now I get a run-time error telling me that there is no attribute called uId. This makes sense since I do not have a uId column in my post domain object (I simply have a reference to a user object). Now I am really confused as to how I can get Hibernate to realize that it needs to map the foreign key from the post table to the user table. Should explicitly add a uId attribute to my post domain object to be a placeholder for the foreign key?
I hope I am making sense...
