Hibernate: getting entity from PostgreSQL view - postgresql

Question

Let's imagine that we have two entities in the database. We have a simple Server with a unique Id:
PostgreSQL:
CREATE TABLE public.servers (
id bigint NOT NULL,
name character varying(64) NOT NULL
);
ALTER TABLE ONLY public.servers
ADD CONSTRAINT servers_pkey PRIMARY KEY (id);
Class entity:
#Entity
#Table(name = "servers")
public class Server {
#Id
private long id;
private String name;
#OneToMany(mappedBy = "server", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
private List<Channel> channels;
public Server() {}
public Server(String name) {
this.name = name;
channels = new ArrayList<>();
}
// Getters and Setters...
}
Each Server can have several Channels that also have a unique id and belong to a server:
PostgreSQL:
CREATE TABLE public.channels (
id bigint NOT NULL,
server_id bigint NOT NULL,
name character varying NOT NULL
);
ALTER TABLE ONLY public.channels
ADD CONSTRAINT channels_pkey PRIMARY KEY (id);
ALTER TABLE ONLY public.channels
ADD CONSTRAINT fkey_channel_server FOREIGN KEY (server_id) REFERENCES public.servers(id);
Class entity:
#Entity
#Table (name = "channels")
public class Channel {
#Id
private long id;
private String name;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "server_sn")
private Server server;
public Channel() {}
public Channel(Server server, String name) {
this.server = server;
this.name = name;
}
// Getters and Setters...
}
Next, I create a View in PostgreSQL:
CREATE VIEW public.summary AS
SELECT servers.s_snowflake AS server_id, channels.c_snowflake AS channel_id, channels.name FROM servers
JOIN channels ON servers.s_snowflake = channels.server_sn;
I want to get data from this view but I'm facing a problem on how to implement the class. I have tried something like this:
#Embeddable
class SummaryPK implements Serializable {
private long server_id;
private long channel_id;
}
#Entity
#Immutable
#Subselect("SELECT * FROM summary")
public class Summary {
#EmbeddedId
private SummaryPK summaryPK;
#MapsId("server_id")
#ManyToOne(fetch = FetchType.LAZY, targetEntity = Server.class)
#JoinColumn(name = "id", insertable = false, updatable = false)
private Server server;
#MapsId("channel_id")
#ManyToOne(fetch = FetchType.LAZY, targetEntity = Channel.class)
#JoinColumn(name = "id", insertable = false, updatable = false)
private Channel channel;
private String name;
// Getters and Setters
}
In the program, I want to receive a list of Entity, for example, by passing the Server ID. Any idea how to implement a working structure here?

Answer 1

Fixed the problem, there were incorrect id in JoinColumn:
#JoinColumn(name = "server_id", insertable = false, updatable = false)
#JoinColumn(name = "channel_id", insertable = false, updatable = false)