来自实体的JPA实体管理器createQuery，不同的包但名称相同

Question

I have the following entities in the module

com.example.Company (table_name: COMPANIES)

com.example.workspace.Company (table_name: WS_COMPANIES)

in main class, i only import the entity import com.example.Company . Then I want to find all companies from DB

TypedQuery<Company> query = (javax.persistence.EntityManager) em.createQuery("from Company", Company.class);

however, i got the error where it tries to query

Type specified for TypedQuery [com.example.Company] is incompatible with query return type [class com.example.workspace.Company]

Is there any method to resolve this, and appreciate if anyone could explain how the entity manager construct the create query?

em.createQuery("from com.example.Company", Company.class) seems to be a way, but it doesn't looks elegant. I might want to have com.example.Company as the default

the below is the persistence.xml file, the classes are in sequence

<persistence-unit name="pcc-cpod-persistence-unit" transaction-type="RESOURCE_LOCAL">
  <provider>org.hibernate.ejb.HibernatePersistence</provider>
  <class>com.example.Company</class>
  <class>com.example.workspace.Company</class>
  <exclude-unlisted-classes>true</exclude-unlisted-classes>
</persistence-unit>

Answer 1

From the JPA specifications:

4.3.1 Naming

Entities are designated in query strings by their entity names. The entity name is defined by the name element of the Entity annotation (or the entity-name XML descriptor element), and defaults to the unqualified name of the entity class. Entity names are scoped within the persistence unit and must be unique within the persistence unit.

Based on this, "from Company" refers to the @Entity with a name="Company". As you are not permitted to have duplicate names, it must be that com.example.Company has a different entity name than "Company". If you look at the @Entity definition for com.example.Company you should find its name, and if you use that name in the SELECT query you should get your desired result.

Answer 2

You can use "name" attribute of "Entity" annotation to distinguish between entities that share same class name and you can refer the value specified in this name" attribute while building the JPQL query.

In your case, you can have

@Entity(name="DefaultCompany")
@Table(name="COMPANIES")
for com.example.Company

@Entity(name="WSCompany")
@Table(name="WS_COMPANIES")
for com.example.workspace.Company 

And in you queries you can refer the entities as below:

em.createQuery("from DefaultCompany", Company.class);
em.createQuery("from WSCompany", Company.class);