Creating Mappings with Hibernate XML Files - Beginning Hibernate: From Novice to Professional - page 154

Table 7-9. Continued

Attribute Values Default Description

insert true , false true Indicates whether the field can be persisted.

When set to false , this prevents inserts if the
field has already been mapped as part of a
composite identifier or some other attribute.

lazy false , proxy , Overrides the entity-loading mode.

noproxy

name The (mandatory) name of the attribute. This

should start with a lowercase letter.

node

Specifies the name of the XML element or attrib-
ute that should be used by the XML relational
persistence features.

not-found exception , exception

The behavior to exhibit if the related entity does

ignore not exist (either throw an exception or ignore the

problem).

not-null true , false false Specifies whether a not-null constraint should

be applied to this column.

optimistic-lock true , false true Specifies whether optimistic locking should be

used.

outer-join true , false ,

Specifies whether an outer join should be used.

auto

property-ref Specifies the column in the target entity's table

that the foreign key references. If the referenced
table's foreign key does not reference the pri-
mary key of the “many” end of the relationship,
then property-ref can be used to specify the col-
umn that it references. This should only be the
case for legacy designs—when creating a new
schema, your foreign keys should always refer-
ence the primary key of the related table.

unique true , false false

Specifies whether a unique constraint should be
applied to the column.

unique-key

Groups the columns together by this attribute
value. Represents columns across which a
unique key constraint should be generated (not
yet supported in the schema generation).

update true , false true

When set to false , prevents updates if the field
has already been mapped elsewhere.

If a unique constraint is specified on a many-to-one relationship, it is effectively converted
into a one-to-one relationship. This approach is preferred over creating a one-to-one association,
both because it results in a simpler mapping and because it requires less intrusive changes to the
database should it become desirable to relax the one-to-one association into a many-to-one.
This element has a small number of optional daughter elements—the <column> element
will be required when a composite key has to be specified:

(meta*, (column | formula)*)