Why you don't find the car and if the car doesn't exists persist it
El 26/09/2012 19:50, <forums_at_java.net> escribió:
> The Car table is a list of cars, all unique. The Engine table is a list of
> engines, all unique. The Report table has a reference to the Car table as
> shown below. There can be many reports, but I don't want to duplicate
> anything in the Car or Engine tables. My problem is I want to insert a
> Report, but only insert a car into the Car table if its not already in the
> Car table. Currently, all this works with the exception that Cars are being
> duplicated into the Car table when I add a report. Any help much
> appreciated.
> [code] ireport = (IReportBean) (new
> InitialContext()).lookup("**java:comp/env/ejb/ReportBean")**; Car car =
> new
> Car(c); Report report = new Report(r); report.addCar(car);
> ireport.addReport(report); [/code] And my EntityManager basically does ...
> [code] em.persist(report); em.flush(); [/code] My table structure ...
> [code]
> CREATE SEQUENCE report_seq START 1000; CREATE TABLE Report ( id INTEGER
> DEFAULT NEXTVAL('report_seq') PRIMARY KEY, car_id INTEGER REFERENCES Car
> (id), condition VARCHAR(32) NOT NULL ); CREATE SEQUENCE car_seq START 1000;
> CREATE TABLE Car ( id INTEGER DEFAULT NEXTVAL('car_seq') PRIMARY KEY,
> engine_id INTEGER REFERENCES Engine (id), mfg VARCHAR(32) NOT NULL );
> CREATE
> SEQUENCE engine_seq START 1000; CREATE TABLE Engine ( id INTEGER DEFAULT
> NEXTVAL('engine_seq') PRIMARY KEY, year VARCHAR(32) NOT NULL, description
> VARCHAR(128) DEFAULT NULL ); [/code] Annotations used in my Report entity.
> [code] @SequenceGenerator(name="**reportIdGen", initialValue=1000,
> allocationSize=50, sequenceName="report_seq") public class Report
> implements
> Serializable { @Id @Column(name="id")
> @GeneratedValue(strategy=**GenerationType.SEQUENCE,
> generator="reportIdGen")
> private Integer id; @ManyToOne(cascade=**CascadeType.PERSIST)
> @JoinColumn(name="car_id") private Car carId; @Column(name="condition")
> private String condition; // ... [/code]
>
> --
>
> [Message sent by forum member 'rrlangly']
>
> View Post: http://forums.java.net/node/**890713<http://forums.java.net/node/890713>
>
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