JPA “contains one of”

问题

I'm writing a Dao to fetch all Messages relevant to a Person. But I can't find the correct JPQL syntax.

In my model:

a Person has multiple Roles (I pass these into the query as a parameter: Set of enum values).
a Message is relevant to multiple Roles.

So I want to find all messages relevant to a person:

SELECT m FROM Message m
WHERE m.roles [contains one of] :userRoles

Giving it :userRoles as a Set<Role> parameter.

What is the correct syntax for that missing [contains one of] section?

I've looked at IN and MEMBER OF e.g.

SELECT m FROM MESSAGE m
WHERE m.roles IN :userRoles

But both those keywords require a single item on one side. I have multiple items on both sides.

More detail:

@Entity
@Table(name = "message")
public class Message {
    @Id
    private Long id;

    @ElementCollection
    @Enumerated(javax.persistence.EnumType.STRING)
    @JoinTable(name="message_roles",
        joinColumns={@javax.persistence.JoinColumn(name="message_id")})
    @Column(name="role_code")
    private Set<Role> roles;

    ...
}

public enum Role {
    DEVELOPER, ADMIN, TESTER, MANAGER
}

This produces a correct-looking table structure of:

message
    message_id

message_roles
    message_id
    role_code

But I can't work out how to query it to see if it contains one of a specific list of given roles.

Must I rewrite it to pass each of the user's roles in individually?

For application-specific reasons I can't join anywhere to get their roles: the roles must be a parameter of the query.

回答1:

Try with this:

SELECT DISTINCT m FROM MESSAGE m JOIN m.roles r WHERE r IN :userRoles

回答2:

I found another way that worked too:

SELECT m FROM Message m
WHERE EXISTS (SELECT 1 FROM m.roles r WHERE r IN (:userRoles))

来源：https://stackoverflow.com/questions/42072771/jpa-contains-one-of

标签

java

hibernate

jpa

jpql