Chapter 47. Mapping Entity Classes

create table ORMCORE_CAR (
    CAR_ID bigint not null,
    CAR_COST decimal(7,2),
    CAR_MAKE varchar(20) not null,
    CAR_MODEL varchar(20) not null,
    CAR_YEAR integer not null,
    primary key (CAR_ID)
)

47.3.2. Mapping Entity Class with Annotations

@Entity

@Table(name="ORMCORE_CAR")

public class Car {    

    @Id

    @Column(name="CAR_ID", nullable=false)

    private long id;

    @Column(name="CAR_MAKE", 

            unique=false, 

            nullable=false, 

            insertable=true,

            updatable=true,

            length=20)

    private String make;

    @Column(name="CAR_MODEL", nullable=false, length=20)

    private String model;    

    @Column(name="CAR_YEAR", nullable=false)

    private int year;

    @Column(name="CAR_COST", precision=7, scale=2)

    private BigDecimal cost;

...

47.3.3. Mapping Entity Class with orm.xml

<entity class="ejava.examples.orm.core.mapped.Car" 

    access="FIELD">

    <table name="ORMCORE_CAR"/>

    <attributes>

        <id name="id">

            <column name="CAR_ID" nullable="false"/>

        </id>

        <basic name="make">

            <column name="CAR_MAKE"

                    nullable="false"

                    insertable="true"

                    updatable="true"

                    length="20"/>

        </basic>

        <basic name="model">

            <column name="CAR_MODEL" nullable="false" length="20"/>

        </basic>

        <basic name="year">

            <column name="CAR_YEAR" nullable="false"/>

        </basic>

        <basic name="cost">

            <column name="CAR_COST" precision="7" scale="2"/>

        </basic>

    </attributes>

</entity>

47.4. More on Precision/Scale

Figure 47.1. More on Scale

//precision defined in ORM as precision=7, scale=2 

car.setCost(new BigDecimal("12345.66"));

em.persist(car);

em.flush(); em.clear();


//get a fresh copy from the DB

Car car2 = em.find(Car.class, car.getId());

log.info("car.cost=" + car.getCost());

log.info("car2.cost=" + car2.getCost());

assertTrue("unexpectected value", car.getCost().equals(car2.getCost()));


//update beyond the scale values -- too many digits to right of decimal

car2.setCost(new BigDecimal("1234.666"));

em.flush(); em.clear();

Car car3 = em.find(Car.class, car.getId());

log.info("car2.cost=" + car2.getCost());

log.info("car3.cost=" + car3.getCost());

assertFalse("unexpected scale", car2.getCost().equals(car3.getCost()));

-car.cost=12345.66     //Value created within scale=2
-car2.cost=12345.66    //Value correctly retrieved from DB     
-car2.cost=1234.666    //Value goes beyond scale=2
-car3.cost=1234.67     //Value rounded down to scale from DB

Figure 47.2. More on Precision


//update beyond the precision values -- too many digits overall

car2 = car3;

car2.setCost(new BigDecimal("123456.66"));

try {

    em.flush();

    fail("database accepted too many digits");

} catch (PersistenceException ex) {

    log.info("caught expected exception:" + ex);

}

-caught expected exception:javax.persistence.PersistenceException: 
org.hibernate.exception.DataException: could not execute statement

47.5. Transient Properties

Entity using PROPERTY access
Entity class contains property that complies with default rules that should *not* be mapped to database

Figure 47.3. Transient Example Entity Class

@Entity

@Table(name="ORMCORE_TANK")

public class Tank {

    private long id;

    private String make;

    private String model;

    

    public Tank() {}

    public Tank(long id) { this.id = id; }

    

    @Id 

    public long getId() { return id; }

    protected void setId(long id) {

        this.id = id;

    }

        

    @Transient    //if you remove this, it will fail trying to locate setter

    public String getMakeModel() {

        return make + " " + model;

    }

    

    public String getMake() { return make; }

    public void setMake(String make) {

        this.make = make;

    }


    public String getModel() { return model; }

    public void setModel(String model) {

        this.model = model;

    }

Figure 47.4. Transient Example orm.xml




<entity class="ejava.examples.orm.core.mapped.Tank" access="PROPERTY">

    <table name="ORMCORE_TANK"/>

    <attributes>

        <id name="id"/>

        <transient name="makeModel"/>            

    </attributes>

</entity>

Figure 47.5. Transient Example Database Schema

create table ORMCORE_TANK (
    id bigint not null,
    make varchar(255),
    model varchar(255),
    primary key (id)
)

Figure 47.6. Transient Example Test

ejava.examples.orm.core.annotated.Tank tank = new Tank(1);

tank.setMake("acme");

tank.setModel("great guns");


//insert a row in the database

em.persist(tank);

log.info("created tank:" + tank);

-created tank:ejava.examples.orm.core.annotated.Tank@4eef4eb7make=acme, model=great guns

Figure 47.7. CLOB Example Database Schema

create table ORMCORE_UMBRELLA (
    id bigint not null,
    make clob,
    model varchar(255),
    primary key (id)
)

Figure 47.8. CLOB Example Entity Class

@Entity

@Table(name="ORMCORE_UMBRELLA")

public class Umbrella {

    @Lob

    @Basic(fetch=FetchType.LAZY) //ignored

    public char[] getMake() {

        return make.toCharArray();

    }

    public void setMake(char[] make) {

        this.make = new String(make);

    }

47.7. Temporal and Enumerated Properties

47.7.1. Temporals

DATE
TIME
TIMESTAMP

47.7.2. Enums

ORDINAL
NAME

47.7.3. Temporal/Enum Example

Figure 47.9. Temporal/Enum Example Schema

create table ORMCORE_VASE (

    id bigint not null,

    aDate date,

    aTime time,

    aTimestamp timestamp,

    colorId integer,

    colorName varchar(255),

    primary key (id)

)

Figure 47.10. Temporal/Enum Example Entity Class

@Entity

@Table(name="ORMCORE_VASE")

public class Vase {

    @Id

    private long id;

    @Temporal(TemporalType.DATE)

    private Date aDate;

    @Temporal(TemporalType.TIME)

    private Date aTime;

    @Temporal(TemporalType.TIMESTAMP)

    private Date aTimestamp;

    @Enumerated(EnumType.ORDINAL)

    private ColorType colorId;

    @Enumerated(EnumType.STRING)

    private ColorType colorName;

Figure 47.11. Temporal/Enum Example orm.xml




<entity class="ejava.examples.orm.core.mapped.Vase" access="FIELD">

    <table name="ORMCORE_VASE"/>

    <attributes>

        <id name="id"/>

        <basic name="aDate">

            <temporal>DATE</temporal>

        </basic>            

        <basic name="aTime">

            <temporal>TIME</temporal>

        </basic>            

        <basic name="aTimestamp">

            <temporal>TIMESTAMP</temporal>

        </basic>            

        <basic name="colorId">

            <enumerated>ORDINAL</enumerated>

        </basic>            

        <basic name="colorName">

            <enumerated>STRING</enumerated>

        </basic>            

    </attributes>

</entity>

Figure 47.12. Temporal/Enum Example Test

@Test

public void testValues() {

    log.info("testValues");

    ejava.examples.orm.core.annotated.Vase vase = new Vase(1);

    Date date = new Date();

    vase.setADate(date);

    vase.setATime(date);

    vase.setATimestamp(date);

    vase.setColorId(ColorType.RED);

    vase.setColorName(ColorType.RED);

    

    //insert a row in the database

    em.persist(vase);

    log.info("created case:" + vase);

    

    //find the inserted object

    em.flush();

    em.clear();

    Vase vase2 = em.find(Vase.class, 1L); 


    log.info("found vase:" + vase2);

-created case:ejava.examples.orm.core.annotated.Vase@7f68f33c, 
    id=1, 
    aDate=Mon Sep 23 00:11:10 EDT 2013, 
    aTime=Mon Sep 23 00:11:10 EDT 2013, 
    aTimestamp=Mon Sep 23 00:11:10 EDT 2013, 
    colorId=RED, 
    colorName=RED
    
-found vase:ejava.examples.orm.core.annotated.Vase@5f0d8b74, 
    id=1, 
    aDate=2013-09-23, 
    aTime=00:11:10, 
    aTimestamp=2013-09-23 00:11:10.296, 
    colorId=RED, 
    colorName=RED

select * from ORMCORE_VASE
ID ADATE      ATIME    ATIMESTAMP                    COLORID COLORNAME
-- ---------- -------- ----------------------------- ------- ---------
1  2006-09-23 14:08:22 2006-09-23 14:08:22.221000000 0       RED

Notice impact of temporal DB-mapping does effect until data saved and retrieved from database