Nikita Timofeev created CAY-2255:
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Summary: ObjectSelect improvement: columns as full entities
Key: CAY-2255
URL: https://issues.apache.org/jira/browse/CAY-2255
Project: Cayenne
Issue Type: Improvement
Components: Core Library
Reporter: Nikita Timofeev
Assignee: Nikita Timofeev
*Changes in API*:
# Add new Expression {{FullObjectExpression}} that will be just a marker for
the desired logic.
This expression can be later (_in post 4.0 versions_) used in {{where()}} and
in {{orderBy()}} methods to act as ObjectId and
thus fill another gap where hacks like {{"db:OBJECT_ID"}} are used now.
# Add new factory methods in Property:
{code}
<T extends Persistent> Property<T> createSelf(Class<? super T> type);
<T extends Persistent> Property<T> createForRelationship(
Property<?> property, Class<? super T> type)
{code}
# Prohibit direct usage of Properties mapped on toMany relationships
*Usage examples*:
# Selecting root object plus some related fields:
{code}
Property<Artist> artistSelf = Property.createSelf(Artist.class);
List<Object[]> result = ObjectSelect.query(Artist.class)
.columns(artistSelf, Artist.ARTIST_NAME, Artist.PAINTING_ARRAY.count())
.select(context);
{code}
# Selecting toOne relationship:
{code}
List<Object[]> result = ObjectSelect.query(Painting.class)
.columns(Painting.PAINTING_TITLE, Painting.TO_ARTIST,
Painting.TO_GALLERY)
.select(context);
{code}
# Selecting toMany relationship, the result will be as it will be in SQL query
{code}
Property<Artist> artist = Property.createSelf(Artist.class);
Property<Painting> artistPainting =
Property.createForRelationship(Artist.PAINTING_ARRAY, Painting.class);
Property<Gallery> artistPaintingGallery =
Artist.PAINTING_ARRAY.dot(Painting.TO_GALLERY);
List<Object[]> result = ObjectSelect.query(Artist.class)
.columns(artist, artistPainting, artistPaintingGallery)
.select(context);
{code}
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