Hibernate Criteria with group by getting error

Hibernate Criteria with group by getting error

我有这两个引用表的实体 java 类(jos_content

我们可以使用投影来缩小选定列的范围，但是我们必须决定

• 我们将使用表示为 object[] 的结果吗
• 我们会将结果转换为 DTO(如果可能的话，转换为原始实体)

如果我们要进行转换，我们必须帮助转换器使用列名。它通过传递 alias

完成

PropertyProjection propProjection = Projections

 .groupProperty("content.id")

   .as("id") // the alias

 ;



contentCriteria

  .setProjection(propProjection)

  .setResultTransformer(Transformers.aliasToBean(ContentEntity.clas????s));



List<ContentEntity> groupedEntities = contentCriteria.list();

Object[] results = contentCriteria.list();
DetachedCriteria grouped = DetachedCriteria.forClass(ContentEntity.class,"grouped")

  // Filter the Subquery

  .add(...

  // SELECT The User Id 

 .setProjection(propProjection)
Criteria query = session.createCriteria(ContentEntity.class,"content")

  .add( Subqueries.propertyIn("content.id", grouped) );

那么结果将是 ContentEntity 的列表，该列表将仅填充 id。请参阅：

• 17.9。预测、聚合和分组

The alias() and as() methods simply wrap a projection instance in another, aliased, instance of Projection.

或者我们可以预期结果为 object[]

PropertyProjection propProjection = Projections

 .groupProperty("content.id")

   .as("id") // the alias

 ;



contentCriteria

  .setProjection(propProjection)

  .setResultTransformer(Transformers.aliasToBean(ContentEntity.clas????s));



List<ContentEntity> groupedEntities = contentCriteria.list();

Object[] results = contentCriteria.list();
DetachedCriteria grouped = DetachedCriteria.forClass(ContentEntity.class,"grouped")

  // Filter the Subquery

  .add(...

  // SELECT The User Id 

 .setProjection(propProjection)
Criteria query = session.createCriteria(ContentEntity.class,"content")

  .add( Subqueries.propertyIn("content.id", grouped) );

扩展：

如果我们想获取路由实体列表，我们可以将当前查询转换为 DetachedCriteria

PropertyProjection propProjection = Projections

 .groupProperty("content.id")

   .as("id") // the alias

 ;



contentCriteria

  .setProjection(propProjection)

  .setResultTransformer(Transformers.aliasToBean(ContentEntity.clas????s));



List<ContentEntity> groupedEntities = contentCriteria.list();

Object[] results = contentCriteria.list();
DetachedCriteria grouped = DetachedCriteria.forClass(ContentEntity.class,"grouped")

  // Filter the Subquery

  .add(...

  // SELECT The User Id 

 .setProjection(propProjection)
Criteria query = session.createCriteria(ContentEntity.class,"content")

  .add( Subqueries.propertyIn("content.id", grouped) );

所以，上面只会返回我们喜欢的ID，主查询会被它们过滤，同时返回完整的对象(无需转换)

PropertyProjection propProjection = Projections

 .groupProperty("content.id")

   .as("id") // the alias

 ;



contentCriteria

  .setProjection(propProjection)

  .setResultTransformer(Transformers.aliasToBean(ContentEntity.clas????s));



List<ContentEntity> groupedEntities = contentCriteria.list();

Object[] results = contentCriteria.list();
DetachedCriteria grouped = DetachedCriteria.forClass(ContentEntity.class,"grouped")

  // Filter the Subquery

  .add(...

  // SELECT The User Id 

 .setProjection(propProjection)
Criteria query = session.createCriteria(ContentEntity.class,"content")

  .add( Subqueries.propertyIn("content.id", grouped) );

在这里检查类似的东西：Hibernate Criteria for "in subselect"