Using field level access for hibernate entities

Hibernate allows you to configure the access mechanism for attributes in the entity object. It can access the attributes directly or through the accessors. The field or property access type is decided by hibernate based on the location of @Id or @EmbeddedId.

@Entity
public class Item {
@Id
public String id;
public long itemNumber;
}

@Entity
public class FoodItem {
private String id;
private long foodId;

@Id
public String getId(){
return id;
}
public long getFoodId(){
return foodId;
}
}

In the above code, Item class uses field access and FoodItem class uses property access.

Using property access mechanism allows classes to hide the internal data structure from the external world and it enables class to perform validations while setting the value or while accessing it. It is useful when we want to perform some calculation before returning the result or setting the value.

However, mostly we end up directly accessing the variable from the getter and setter methods. In that case, property access is overkill. It makes us write lot of getter - setters which are not used anywhere else in the code. It also exposes setters if when we don't want anyone to set the value of fields like 'id'. We can mark the accessors private or protected and avoid this problem, but we will still have the code.

IMHO, while creating the entity, we should start with field level access. Doing so will reduce the unnecessary code which is used only by hibernate. We should keep the fields private and provide accessor methods only when required. So our entity object will be modeled by the needs of the application and not by the hibernate. In future, if we need to validate or manipulate the values set on the object (which mostly won't happen), we can then switch to property access, but we shouldn't start with it.