休眠-如何持久保存用公式映射的属性

Question

This question is very similar to the one asked here

Could someone shed some light as why hibernate decides to ignore the property, which has a formula, completely while persisting. If so whats the alternative to persist a property which has a formula ? is there any additional config ?

Query fired by hibernate :

insert into fighterjet (max_speed, country, jet_id) values (?, ?, ?)

Note how hibernate ignores the 'name' property in the insert query, which has a formula in the hbm.

HBM :

<hibernate-mapping>
    <class name="com.fighterjet.FighterjetDO" table="fighterjet">
        <id name="jetId" type="int" column="jet_id">
            <generator class="increment" />
        </id>
        <property name="name" formula="Select 'hi' from dual" >
            <column name="name"/>
        </property>
        <property name="maxSpeed">
            <column name="max_speed" />
        </property>
        <property name="country">
            <column name="country" />
        </property>
    </class>
</hibernate-mapping>

Class :

public class FighterjetDO {

    private Integer jetId;

    private String name;

    private Integer maxSpeed;

    private String country;

    public Integer getJetId() {
        return jetId;
    }

    public void setJetId(Integer jetId) {
        this.jetId = jetId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getMaxSpeed() {
        return maxSpeed;
    }

    public void setMaxSpeed(Integer maxSpeed) {
        this.maxSpeed = maxSpeed;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    @Override
        public String toString() {
            return "FighterJet [Jet_id=" + jetId + ", Name=" + name
                    + ", Max Speed=" + maxSpeed + ", Country=" + country+ "]";
        }   


}

Answer 1

As per hibernate documentation it says:

5.1.4.2. Property mapping with hbm.xml

formula (optional): an SQL expression that defines the value for a computed property. Computed properties do not have a column mapping of their own.

So the property with Formula cannot have a column mapping in DB table. As an alternative you can have another property that can hold its value and you can map this new property to your DB table column.