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SUMMARY: REQUIRED | OPTIONAL | DETAIL: ELEMENT |
@Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface OrderBy
Specifies the ordering of the elements of a collection valued association or element collection at the point when the association or collection is retrieved.
The syntax of the value
ordering element is an
orderby_list
, as follows:
orderby_list::= orderby_item [,orderby_item]* orderby_item::= [property_or_field_name] [ASC | DESC]
If ASC
or DESC
is not specified,
ASC
(ascending order) is assumed.
If the ordering element is not specified for an entity association, ordering by the primary key of the associated entity is assumed.
The property or field name must correspond to that of a persistent property or field of the associated class or embedded class within it. The properties or fields used in the ordering must correspond to columns for which comparison operators are supported.
The dot (".") notation is used to refer to an attribute within an embedded attribute. The value of each identifier used with the dot notation is the name of the respective embedded field or property.
The OrderBy
annotation may be applied to an element
collection. When OrderBy
is applied to an element collection of
basic type, the ordering will be by value of the basic objects and
the property or field name is not used. When specifying an ordering
over an element collection of embeddable type, the dot notation
must be used to specify the attribute or attributes that determine
the ordering.
The OrderBy
annotation is not used when an order
column is specified.
Example 1: @Entity public class Course { ... @ManyToMany @OrderBy("lastname ASC") public List<Student> getStudents() {...}; ... } Example 2: @Entity public class Student { ... @ManyToMany(mappedBy="students") @OrderBy // ordering by primary key is assumed public List<Course> getCourses() {...}; ... } Example 3: @Entity public class Person { ... @ElementCollection @OrderBy("zipcode.zip, zipcode.plusFour") public Set<Address> getResidences() {...}; ... } @Embeddable public class Address { protected String street; protected String city; protected String state; @Embedded protected Zipcode zipcode; } @Embeddable public class Zipcode { protected String zip; protected String plusFour; }
OrderColumn
Optional Element Summary | |
---|---|
java.lang.String |
value
An orderby_list . |
public abstract java.lang.String value
orderby_list
. Specified as follows:
orderby_list::= orderby_item [,orderby_item]* orderby_item::= [property_or_field_name] [ASC | DESC]
If ASC
or DESC
is not specified,
ASC
(ascending order) is assumed.
If the ordering element is not specified, ordering by the primary key of the associated entity is assumed.
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Generated on 10-February-2011 12:41