JPA SortedMap mapping - avoid two columns with keys - jpa

Question

I have two classes, CalculatedValue and Price. Price has map of CalculatedValue. Each CalculableValue instance has name, value and couple of other fields.
Here is mapping I use to describe a dependency between Price and the CV:
#OneToMany(
cascade = CascadeType.ALL,
fetch = FetchType.EAGER
)
#JoinColumn(name = "priceId")
private Map<String, CalculatedValue> calculatedValues =
new TreeMap<String, CalculatedValue>();
No join table, just mapping by priceId column which refers to Price unique Id.
Here is how generated table looks like:
CREATE TABLE PUBLIC.CALCULATEDVALUE (
UNIQUEID BIGINT NOT NULL,
KEY VARCHAR(2147483647) NOT NULL,
PRICEID BIGINT,
VALUE DOUBLE NOT NULL,
CALCULATEDVALUES_KEY VARCHAR(2147483647),
PRIMARY KEY (UNIQUEID)
);
ALTER TABLE PUBLIC.CALCULATEDVALUE
ADD FOREIGN KEY (PRICEID)
REFERENCES TEST.PUBLIC.PRICE (UNIQUEID);
Everything is working, but I want to know if it possible to to this:
Avoid automatic "CALCULATEDVALUES_KEY" column creation. I already have this value stored in KEY column and it would be nice to avoid duplication and somehow give a hint to JPA.
Trigger cascade delete of calculable value for each removed price (in case I'm running SQL delete statement)
Will such mapping work in case I'll use Date as a key? Not for this particular field, but for a bunch of other ones it will be useful. Assuming the same OneToMany relationship.
Thank you in advance!
PS. I'm using latest version of EclipseLink & H2 as database.
PPS. Didn't want to store the calculable values in array since I need to often find it buy key in Java.

Answer 1

For info on Maps see,
http://en.wikibooks.org/wiki/Java_Persistence/OneToMany
and,
http://en.wikibooks.org/wiki/Java_Persistence/Relationships#Maps
and,
http://www.eclipse.org/eclipselink/documentation/2.4/jpa/extensions/a_cascadeondelete.htm#CIABIIEB
A few issues:
EclipseLink will use Hashtable by default for Map, if you want it to use TreeMap you need to define the field as TreeMap.
Do not give a #JoinColumn on a #OneToMany, this is only supported for advanced unidirectional #OneToMany, a normal #OneToMany should use a mappedBy and have an inverse #ManyToOne in the target entity. (this will fix your issue of the duplicate foreign key).
You need to specify the #MapKey for a map, otherwise it defaults to the id, which seems to be an integer here, not a string.
You can use #CascadeOnDelete in EclipseLink to cascade a delete on the database.