NPersistence Reference Guide
Defines a many-valued association with many-to-many multiplicity.

Every many-to-many association has two sides, the owning side and the non-owning, or inverse, side. The join table is specified on the owning side. If the association is bidirectional, either side may be designated as the owning side. If the relationship is bidirectional, the non-owning side must use the mappedBy element of the ManyToMany annotation to specify the relationship field or property of the owning side.

The join table for the relationship, if not defaulted, is specified on the owning side.

The ManyToMany annotation may be used within an embeddable class contained within an entity class to specify a relationship to a collection of entities. If the relationship is bidirectional and the entity containing the embeddable class is the owner of the relationship, the non-owning side must use the mappedBy element of the ManyToMany annotation to specify the relationship field or property of the embeddable class. The dot (".") notation syntax must be used in the mappedBy element to indicate the relationship attribute within the embedded attribute. The value of each identifier used with the dot notation is the name of the respective embedded field or property.

Examples

CopyC#
Example 1:

// In Customer class:

[ManyToMany] 
[JoinTable(name="CUST_PHONES")]
public Set<PhoneNumber> getPhones() { return phones; }

// In PhoneNumber class:

[ManyToMany(mappedBy="phones")]
public Set<Customer> getCustomers() { return customers; }

Example 2:

// In Customer class:

[ManyToMany(targetEntity=com.acme.PhoneNumber.class)]
public Set getPhones() { return phones; }

// In PhoneNumber class:

[ManyToMany(targetEntity=com.acme.Customer.class, mappedBy="phones")]
public Set getCustomers() { return customers; }

Example 3:

// In Customer class:

[ManyToMany]
[JoinTable(name="CUST_PHONE")]
        [JoinColumn(AttributeRef="CUST_PHONE",name="CUST_ID", referencedColumnName="ID")]
        [JoinColumn(AttributeRef="CUST_PHONE",name="PHONE_ID", referencedColumnName="ID", Inverse=true)]
    )
public Set<PhoneNumber> getPhones() { return phones; }

// In PhoneNumberClass:

[ManyToMany(mappedBy="phones")]
public Set<Customer> getCustomers() { return customers; }

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

Syntax

   
 C# 
public sealed class ManyToMany : Attribute

Members

         
 All Members  Constructors   Fields  
 Public

 Protected
 Instance

 Static 
 Declared

 Inherited
 XNA Framework Only 

 .NET Compact Framework Only 

 MemberDescription
ManyToMany()()()()
Initializes a new instance of the ManyToMany class
Cascade
(Optional) The operations that must be cascaded to the target of the association. When the target collection is a Dictionary<(Of <(<'TKey, TValue>)>)>, the cascade element applies to the map value. Defaults to no operations being cascaded.
Fetch
(Optional) Whether the association should be lazily loaded or must be eagerly fetched. The EAGER strategy is a requirement on the persistence provider runtime that the associated entities must be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime.
MappedBy
The field that owns the relationship. Required unless the relationship is unidirectional.
TargetEntity
(Optional) The entity class that is the target of the association. Optional only if the collection-valued relationship property is defined using generics. Must be specified otherwise.

Defaults to the parameterized type of the collection when defined using generics.

Inheritance Hierarchy

System..::..Object
  System..::..Attribute
    NPersistence..::..ManyToMany

See Also