Java Reference
In-Depth Information
When mapping enumeration attributes to columns, the
enumeration
Attributes2columns()
query invokes the
enumerationAttribute2col-
umn()
mapping for each attribute. A
when
clause checks that the passed prop-
erty is an enumeration using the
isEnumeration()
query, which checks that its
type attribute is of type
UML::Enumeration
.
Again, the
isPrimaryKey
property is set using the
isPrimaryKey()
query,
and the
name
attributes are directly mapped. The column's type is set to a new
PrimitiveDataType
object initialized with a name of
'int'
.
query
UML::DataType::enumerationAttributes2columns(
in
targetType:
UML::DataType) :
OrderedSet
(RDB::TableColumn) {
self
.attributes->
collect
(
map
enumerationAttribute2column(targetType))->asOrderedSet()
}
mapping
UML::Property::enumerationAttribute2column(
in
targetType:
UML::DataType) : RDB::TableColumn
when
{
self
.isEnumeration() }
{
isPrimaryKey :=
self
.isPrimaryKey();
name :=
self
.name;
type :=
object
RDB::datatypes::PrimitiveDataType { name := 'int'; };
}
query
UML::Property::isEnumeration() :
Boolean
{
type.
oclIsKindOf
(UML::Enumeration)
}
Relationships are mapped to columns using the
relationshipAttributes
2columns()
query. Unlike the primitive and enumeration types, which map to
simple columns, relationships involve the creation of foreign keys. The input
targetType
parameter is passed to the
relationshipAttribute
2foreignKey()
mapping, where a
when
clause checks that it is a relationship
type using the
isRelationship()
query. In this case, valid relationships are
data types that are persistent.
Looking closer at our
relationshipAttributes2columns()
query, after
the collection of
ForeignKey
elements, those that are undefined are rejected.
From this collection, the
TableColumn
objects from each
includedColumns
attribute of the foreign keys are collected and returned in an ordered set.
query
UML::DataType::relationshipAttributes2columns(
in
targetType:
UML::DataType) :
OrderedSet
(RDB::TableColumn) {
self
.attributes->
collect
(
map
relationshipAttribute2foreignKey(targetType))->
reject
(a |
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