OrderBy Class
NPersistence Reference Guide
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:

Examples

CopyC#
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.

Examples

CopyC#
Example 1:

[Entity] 
public class Course {
   ...
   [ManyToMany]
   [OrderBy("lastname ASC")]
   public List<Student> getStudents() {...};
   ...
}

Example 2:

[Entity] 
public class Student {
   ...
   [ManyToMany(mappedBy="students")]
   // 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;
}

Namespace: NPersistence
Assembly: NPersistence (in NPersistence.dll) Version: 2.0.0.0 (2.0.0.0)

Syntax

   
 C# 
public sealed class OrderBy : Attribute

Members

         
 All Members  Constructors   Fields  
 Public

 Protected
 Instance

 Static 
 Declared

 Inherited
 XNA Framework Only 

 .NET Compact Framework Only 

 MemberDescription
OrderBy()()()()
Initializes a new instance of the OrderBy class
OrderBy(String)
Initializes a new instance of the OrderBy class
Value
An orderby_list. Specified as follows:

Examples

CopyC#
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.

Inheritance Hierarchy

System..::..Object
  System..::..Attribute
    NPersistence..::..OrderBy

See Also