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Re: [eclipselink-users] Help with PrimaryKey usage for legacy tables
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Hello,
LineItem has a composite primary key, and so requires a PK class, which
can be specified using the @IdClass annotation on the entity. If you
are using the JPA 1.0 spec, it only allows basic fields to be apart of
the primary key so in addition to the ManyToOne mapping, the LineItem
will need a String orderNo attribute that is marked as updateable=false
insertable=false (or you will get a multiple writeable mapping exception
if both are writable). This string will need to be marked as ID, and
the attribute added to the Primary Key class for LineItem.
If you want to try out the future JPA 2.0 specification (EclpseLink 2.0
implements a version of the draft), it allows the ManyToOne to be marked
as an ID - so you don't need to add string in LineItem for the Order_No
column. You will still need a primary key class for LineItem though.
Also, the mappings you have provided are not correct - the OneToMany
mapping is defaulting to using a join table because it is missing the
mappedby="order", and the ManyToOne LineItem->Order isn't specifying the
column to use and so will default to order_order_no.
Best Regards,
Chris
cmathrusse wrote:
I'm using EclipseLink 1.1.1 and I'm trying to map a parent-child relationship
which exists in legacy tables. I read through the documentation but I'm
still a bit confused by it.
An order's primary key is a String (order_no) that is defined as unique.
LineItems have an association to the order. The lineItem table has the
order_no field and a line_no. It is a combination of order_no and line_no
that make the PrimaryKey for the LineItem. The LineItem line_no is not
unique within the table but is only unique with the addition of the
order_no.
I've tried a few different ways of defining the @Id but nothing seems to be
quite right and the table generation is not correct. I expect the Order to
have an order_no column and the LineItem table to have a composite key of
order_no and line_no.
My objects:
Order {
@Id
@Column(name = "ORDER_NO", length = 12)
private String orderNo;
@OneToMany(fetch = FetchType.EAGER)
private java.util.List<LineItem> lineItems;
...
}
LineItem {
@ManyToOne
private Order order;
@Id
@Column(name = "LINE_NO", nullable = false)
private Integer lineNo;
}
Thanks for the help....
