更新时间:2023-11-30 14:21:22
Update: I tested the approach suggested below and I couldn't get it working for this particular scenario, Hibernate expects you to select columns for all attributes while we definitely don't want the id. However, using a ResultTransformer
did work:
16.1.5. Returning non-managed entities
It is possible to apply a
ResultTransformer
to native SQL queries, allowing it to return non-managed entities.sess.createSQLQuery("SELECT NAME, BIRTHDATE FROM CATS") .setResultTransformer(Transformers.aliasToBean(CatDTO.class))
This query specified:
- the SQL query string
- a result transformer
The above query will return a list of CatDTO which has been instantiated and injected the values of NAME and BIRTHNAME into its corresponding properties or fields.
The documentation mentions returning non-managed entities but it also work with an entity (there is no reason it wouldn't work) and I could persist
the transient entity successfully.
I'm leaving the initial answer for clarity sake.
Maybe the following will help:
16.1.2. Entity queries
The above queries were all about returning scalar values, basically returning the "raw" values from the resultset. The following shows how to get entity objects from a native sql query via
addEntity()
.sess.createSQLQuery("SELECT * FROM CATS").addEntity(Cat.class); sess.createSQLQuery("SELECT ID, NAME, BIRTHDATE FROM CATS").addEntity(Cat.class);
This query specified:
- the SQL query string
- the entity returned by the query
Assuming that Cat is mapped as a class with the columns ID, NAME and BIRTHDATE the above queries will both return a List where each element is a Cat entity.
If the entity is mapped with a many-to-one to another entity it is required to also return this when performing the native query, otherwise a database specific "column not found" error will occur. The additional columns will automatically be returned when using the * notation, but we prefer to be explicit as in the following example for a many-to-one to a Dog:
sess.createSQLQuery("SELECT ID, NAME, BIRTHDATE, DOG_ID FROM CATS").addEntity(Cat.class);
This will allow
cat.getDog()
to function properly.
But I don't think you should set the ID if you want to save it and want Hibernate to perform an insert.