One-to-one mapping |
Use a One-to-One Mapping to define a relationship with one-to-many multiplicity.
In the Persistence Outline view, select the field to map. The Persistence Properties view (for attributes) displays the properties for the selected.
In the Map As field, select One-to-one.
Use this table to complete the remaining fields on the Persistence Properties view.
Property | Description | Default |
---|---|---|
Target Entity | The entity to which this attribute is mapped. | null
You do not need to explicitly specify the target entity, since it can be inferred from the type of object being referenced. |
Cascade Type | See "Cascade Type" for details.
|
Default |
Fetch Type | Defines how data is loaded from the database. See "Fetch Type" for details.
|
Eager |
Optional | Specifies if this field is can be null. | Yes |
Mapped By | The database field that owns the relationship. |
|
Join Column | Specify a mapped column for joining an entity association. See "Join Columns" for details. |
|
Eclipse adds the following annotations to the field:
@OneToOne(targetEntity=<TARGET_ENTITY>, cascade=CascadeType.<CASCADE_TYPE>, fetch = FetchType.<FETCH_TYPE>, mappedBy = "<MAPPED_BY>") @JoinTable(joinColumns=@JoinColumn(name="<JOIN_COLUMN_NAME>"))