Question

How does Hibernate recognize a change in a object? Is it inspecting the field directly or using the associated Getter-method?

Say i have a price column in the database. Under certain conditions the price shall be converted. Can i do this in the Getter-method and return the converted value without changing the value of this column if i persist this object? A change made by the Setter of this property should change the column though.

What is the default behaviour? Can it be changed? Is this a good practice or should it be avoided by using a “getConvertedPrice”-method, because the behaviour may change with a different configuration/version which yields to hard-to-find bugs?

Edit: Request Example code …

@Entity
@Table(name="items")
public class Item {
    /*...*/
    @Column(name="item_price")
    private double price;

    @Column(name="item_currency")
    // More enum mapping ...
    private Currency currency;

    public void setPrice(double price) {
        this.price = price;
    }

    public double getPrice() {
        if(getCurrency()!=Currency.US_DOLLAR) {
            return price * CurrencyService.getCurrentRate(getCurrency());
        } else {
            return price;
        }
    }
    /*..*/
}

Answer 1

It depends on access type of an entity. By default it’s deduced from placement of mapping annotations (on fields or on properties).

You can override access type for specific field using @Access annotation (or @AccessType for old versions of Hibernate).