This class has a composite primary key. It must use an ID class.

[Philippe Ponceblanc]

Hello,
I have a class that is annotated by several @Id, it makes me an error on the @Entity of this class.

How can I remove this error?

package flights;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;

@Entity // This class has a composite primary key. It must use an ID class.
public class Route implements Serializable {
	private static final long serialVersionUID = -2403746842148223177L;
	
	private String airlineCode;
	
	@ManyToOne
	@Id
	private Airline airline;
	
	private String sourceCode;
	
	@ManyToOne
	@Id
	private Airport source;
	
	private String destinationCode;
	
	@ManyToOne
	@Id
	private Airport destination;
	
	private Boolean codeshare;
	
	private Short stops;
	
	private String equipment;
      /**
      *****************************
     Getters and Setters
     *******************************
       */

[Stephan van Hulst]

A quick google search implies you need to make a separate class for the compound key and embed it:

@Embeddable
public final class RouteId implements Serializable {

  @ManyToOne
  private Airline airline;

  @ManyToOne
  private Aiport airport;

  @ManyToOne
  private Airport destination;

}

@Entity
public final class Route implements Serializable {

  @Id
  private RouteId id;

  private String sourceCode;

  private String destinationCode;

  private boolean codeshare;

  private short stops;

  private String equipment;

}

[Philippe Ponceblanc]

thanks

Just one problem are in this code,
the @Embeddable = i don't know and generate error == The Java class for mapped type "flights.RouteId" is final

@Embeddable // error  :The Java class for mapped type "flights.RouteId" is final
public final class RouteId implements Serializable {

  @ManyToOne
  private Airline airline;
 
  @ManyToOne
  private Airport airport;
 
  @ManyToOne
  private Airport destination;
	  

[Stephan van Hulst]

I'm not super familiar with JPA, but it seems that they need to create proxy classes to function properly. That means classes need to be non-final. I write final by default, but apparently that won't work in this situation.

[Philippe Ponceblanc]

Hello,
it seems to me that the solution is in the following link:

https://translate.googleusercontent.com/translate_c?depth=1&hl=fr&prev=search&rurl=translate.google.fr&sl=en&sp=nmt4&u=https://stackoverflow.com/questions/12106124/eclipse-error-on-mapping-with-embeddedid/26540478&xid=17259,15700022,15700124,15700149,15700186,15700190,15700201,15700214&usg=ALkJrhhzOhaLrScUn08Avq9yMriYEEAkLw

I do not understand everything but I use JPA version 2.1, I do not know the specification of the latter, but there is a way around the problem.

Add that the English language is not my mother tongue and I have trouble translating!

could anyone help me?

[Rob Spoor]

Your primary key class needs to have an equals and hashCode method.

When I create primary key classes I never put the associations in it, only fields matching their primary keys. The association then goes in the entity class with @MapsId. For instance:

@Entity
public class Route {

    @EmbeddedId
    private RouteId id;

    private String airlineCode;

    @ManyToOne
    @MapsId("airlineId")
    private Airline airline;

    private String sourceCode;

    @ManyToOne
    @MapsId("sourceId")
    private Airport source;
     
    private String destinationCode;
     
    @ManyToOne
    @MapsId("destinationId")
    private Airport destination;
     
    private Boolean codeshare;
     
    private Short stops;
     
    private String equipment;
}

@Embeddable
public final class RouteId implements Serializable {

    private static final long serialVersionUID = ...;

    // assuming all Long ids
    private Long airlineId;
    private Long sourceId;
    private Long destinationId;

    // Omitted: constructors, getters/setters
    // Omitted: equals, hashCode and toString methods
}

You will need to make sure to keep the RouteId instance and the many-to-one fields in sync. Best way to do this is to make the non-argument constructor protected, and add a public constructor that takes these fields and uses them to create the RouteId instance for you. You don't want any setters anyway, because you should never update your primary key.

[Philippe Ponceblanc]

I admit that I have trouble following, now I have multiple mistakes which I know what to do to solve them.

Here's my code, I hope I'm not wrong:

>> Class Route

package flights;

import java.io.Serializable;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.MapsId;

	@Entity
	public class Route {
		@EmbeddedId // Embedded ID class should include method definitions for equals() and hashcode()
	    private RouteId id;
	 
	    private String airlineCode;
	 
	    @ManyToOne //The type of the ID mapped by the relationship 'airline' does not agree with the primary key class of the target entity.
	    @MapsId("airlineId")
	    private Airline airline;
	 
	    private String sourceCode;
	 
	    @ManyToOne // The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.
	    @MapsId("sourceId")
	    private Airport source;
	      
	    private String destinationCode;
	      
	    @ManyToOne // The type of the ID mapped by the relationship 'destination' does not agree with the primary key class of the target entity.
	    @MapsId("destinationId")
	    private Airport destination;
	      
	    private Boolean codeshare;
	      
	    private Short stops;
	      
	    private String equipment; 
	    public RouteId getId() {
			return id;
		}

		public void setId(RouteId id) {
			this.id = id;
		}

		public String getAirlineCode() {
			return airlineCode;
		}

		public void setAirlineCode(String airlineCode) {
			this.airlineCode = airlineCode;
		}

		public Airline getAirline() {
			return airline;
		}

		public void setAirline(Airline airline) {
			this.airline = airline;
		}

		public String getSourceCode() {
			return sourceCode;
		}

		public void setSourceCode(String sourceCode) {
			this.sourceCode = sourceCode;
		}

		public Airport getSource() {
			return source;
		}

		public void setSource(Airport source) {
			this.source = source;
		}

		public String getDestinationCode() {
			return destinationCode;
		}

		public void setDestinationCode(String destinationCode) {
			this.destinationCode = destinationCode;
		}

		public Airport getDestination() {
			return destination;
		}

		public void setDestination(Airport destination) {
			this.destination = destination;
		}

		public Boolean getCodeshare() {
			return codeshare;
		}

		public void setCodeshare(Boolean codeshare) {
			this.codeshare = codeshare;
		}

		public Short getStops() {
			return stops;
		}

		public void setStops(Short stops) {
			this.stops = stops;
		}

		public String getEquipment() {
			return equipment;
		}

		public void setEquipment(String equipment) {
			this.equipment = equipment;
		}

	
	}
	 

>> Class RouteId

package flights;

import java.io.Serializable;

import javax.persistence.Embeddable;

@Embeddable // The Java class for mapped type "flights.RouteId" is final
public final class RouteId implements Serializable {
 
    private static final long serialVersionUID = -2403746842148223177L;
 
    // assuming all Long ids
    private Long airlineId;
    private Long sourceId;
    private Long destinationId;
 
    // Omitted: constructors, getters/setters
    // Omitted: equals, hashCode and toString methods
}

if you have URL link to give me to understand I want, because this way of coding comes out of the course !

Regards
Philippe

[Dave Tolls]

What errors are you getting?

(Note that the RouteId is supposed to have getters and setters)

[Philippe Ponceblanc]

Dave Tolls wrote:What errors are you getting?
(Note that the RouteId is supposed to have getters and setters)

Errors are annotated in green writing with error !

Class RouteId :

package flights;

import java.io.Serializable;

import javax.persistence.Embeddable;

@Embeddable // error : The Java class for mapped type "flights.RouteId" is final
public final class RouteId implements Serializable {
 
    private static final long serialVersionUID = -2403746842148223177L;
 // assuming all Long ids
    private Long airlineId;
    private Long sourceId;
    private Long destinationId;
    
    
    public Long getAirlineId() {
		return airlineId;
	}
	public void setAirlineId(Long airlineId) {
		this.airlineId = airlineId;
	}
	public Long getSourceId() {
		return sourceId;
	}
	public void setSourceId(Long sourceId) {
		this.sourceId = sourceId;
	}
	public Long getDestinationId() {
		return destinationId;
	}
	public void setDestinationId(Long destinationId) {
		this.destinationId = destinationId;
	}
	public static long getSerialversionuid() {
		return serialVersionUID;
	}
	
 
    // Omitted: constructors, getters/setters
    // Omitted: equals, hashCode and toString methods
}

Class Route :

package flights;
 
import java.io.Serializable;
 
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.MapsId;
 
    @Entity
    public class Route {
        @EmbeddedId // error : Embedded ID class should include method definitions for equals() and hashcode()
        private RouteId id;
 
        private String airlineCode;
 
        @ManyToOne // error : The type of the ID mapped by the relationship 'airline' does not agree with the primary key class of the target entity.
        @MapsId("airlineId")
        private Airline airline;
 
        private String sourceCode;
 
        @ManyToOne // error : The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.
        @MapsId("sourceId")
        private Airport source;
 
        private String destinationCode;
 
        @ManyToOne // error : The type of the ID mapped by the relationship 'destination' does not agree with the primary key class of the target entity.
        @MapsId("destinationId")
        private Airport destination;
 
        private Boolean codeshare;
 
        private Short stops;
 
        private String equipment; 
        public RouteId getId() {
            return id;
        }
 
        public void setId(RouteId id) {
            this.id = id;
        }
 
        public String getAirlineCode() {
            return airlineCode;
        }
 
        public void setAirlineCode(String airlineCode) {
            this.airlineCode = airlineCode;
        }
 
        public Airline getAirline() {
            return airline;
        }
 
        public void setAirline(Airline airline) {
            this.airline = airline;
        }
 
        public String getSourceCode() {
            return sourceCode;
        }
 
        public void setSourceCode(String sourceCode) {
            this.sourceCode = sourceCode;
        }
 
        public Airport getSource() {
            return source;
        }
 
        public void setSource(Airport source) {
            this.source = source;
        }
 
        public String getDestinationCode() {
            return destinationCode;
        }
 
        public void setDestinationCode(String destinationCode) {
            this.destinationCode = destinationCode;
        }
 
        public Airport getDestination() {
            return destination;
        }
 
        public void setDestination(Airport destination) {
            this.destination = destination;
        }
 
        public Boolean getCodeshare() {
            return codeshare;
        }
 
        public void setCodeshare(Boolean codeshare) {
            this.codeshare = codeshare;
        }
 
        public Short getStops() {
            return stops;
        }
 
        public void setStops(Short stops) {
            this.stops = stops;
        }
 
        public String getEquipment() {
            return equipment;
        }
 
        public void setEquipment(String equipment) {
            this.equipment = equipment;
        }
 
 
    }

[Dave Tolls]

For the first one, I think this was mentioned earlier.
The class cannot be final as JPA/Hibernate needs to be able to extend the class as part of how it handles persistence.

The next says exactly what the issue is (again, I think this was brought up earlier).  You need valid equals and hashcode methods.

The following three imply that the primary keys for those classes are not Long, which is what you are using in the RouteId class.
The fields have to match.

[Philippe Ponceblanc]

Dave Tolls wrote:For the first one, I think this was mentioned earlier.
The class cannot be final as JPA/Hibernate needs to be able to extend the class as part of how it handles persistence.

The next says exactly what the issue is (again, I think this was brought up earlier).  You need valid equals and hashcode methods.

The following three imply that the primary keys for those classes are not Long, which is what you are using in the RouteId class.
The fields have to match.

1/ RouteId Class == OK

2/ i put valid equals and hashcode methods === OK

3/ yet the errors that i don't anderstand in Route Class == ???
   I do not repeat the mistakes but I must also assimilate, otherwise it is useless, if I do not understand what I code.
   Nothing is going to be an example with my code so that I understand a good time, that will serve me as reference code!

package flights;

import java.io.Serializable;

import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.MapsId;

	@Entity
	public class Route {

		@EmbeddedId // error : Embedded ID class should include method definitions for equals() and hashcode()
	    private RouteId id;
	 
	    private String airlineCode;
	 
	    @ManyToOne // error : The type of the ID mapped by the relationship 'airline' does not agree with the primary key class of the target entity.
	    @MapsId("airlineId")
	    private Airline airline;
	 
	    private String sourceCode;
	 
	    @ManyToOne // error :  The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.
	    @MapsId("sourceId")
	    private Airport source;
	      
	    private String destinationCode;
	      
	    @ManyToOne //  error : The type of the ID mapped by the relationship 'destination' does not agree with the primary key class of the target entity.
	    @MapsId("destinationId")
	    private Airport destination;
	      
	    private Boolean codeshare;
	      
	    private Short stops;
	      
	    private String equipment; 
	    public RouteId getId() {
			return id;
		}

		public void setId(RouteId id) {
			this.id = id;
		}

		public String getAirlineCode() {
			return airlineCode;
		}

		public void setAirlineCode(String airlineCode) {
			this.airlineCode = airlineCode;
		}

		public Airline getAirline() {
			return airline;
		}

		public void setAirline(Airline airline) {
			this.airline = airline;
		}

		public String getSourceCode() {
			return sourceCode;
		}

		public void setSourceCode(String sourceCode) {
			this.sourceCode = sourceCode;
		}

		public Airport getSource() {
			return source;
		}

		public void setSource(Airport source) {
			this.source = source;
		}

		public String getDestinationCode() {
			return destinationCode;
		}

		public void setDestinationCode(String destinationCode) {
			this.destinationCode = destinationCode;
		}

		public Airport getDestination() {
			return destination;
		}

		public void setDestination(Airport destination) {
			this.destination = destination;
		}

		public Boolean getCodeshare() {
			return codeshare;
		}

		public void setCodeshare(Boolean codeshare) {
			this.codeshare = codeshare;
		}

		public Short getStops() {
			return stops;
		}

		public void setStops(Short stops) {
			this.stops = stops;
		}

		public String getEquipment() {
			return equipment;
		}

		public void setEquipment(String equipment) {
			this.equipment = equipment;
		}

		@Override
		public int hashCode() {
			final int prime = 31;
			int result = 1;
			result = prime * result + ((airline == null) ? 0 : airline.hashCode());
			result = prime * result + ((airlineCode == null) ? 0 : airlineCode.hashCode());
			result = prime * result + ((codeshare == null) ? 0 : codeshare.hashCode());
			result = prime * result + ((destination == null) ? 0 : destination.hashCode());
			result = prime * result + ((destinationCode == null) ? 0 : destinationCode.hashCode());
			result = prime * result + ((equipment == null) ? 0 : equipment.hashCode());
			result = prime * result + ((id == null) ? 0 : id.hashCode());
			result = prime * result + ((source == null) ? 0 : source.hashCode());
			result = prime * result + ((sourceCode == null) ? 0 : sourceCode.hashCode());
			result = prime * result + ((stops == null) ? 0 : stops.hashCode());
			return result;
		}

		@Override
		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;
			Route other = (Route) obj;
			if (airline == null) {
				if (other.airline != null)
					return false;
			} else if (!airline.equals(other.airline))
				return false;
			if (airlineCode == null) {
				if (other.airlineCode != null)
					return false;
			} else if (!airlineCode.equals(other.airlineCode))
				return false;
			if (codeshare == null) {
				if (other.codeshare != null)
					return false;
			} else if (!codeshare.equals(other.codeshare))
				return false;
			if (destination == null) {
				if (other.destination != null)
					return false;
			} else if (!destination.equals(other.destination))
				return false;
			if (destinationCode == null) {
				if (other.destinationCode != null)
					return false;
			} else if (!destinationCode.equals(other.destinationCode))
				return false;
			if (equipment == null) {
				if (other.equipment != null)
					return false;
			} else if (!equipment.equals(other.equipment))
				return false;
			if (id == null) {
				if (other.id != null)
					return false;
			} else if (!id.equals(other.id))
				return false;
			if (source == null) {
				if (other.source != null)
					return false;
			} else if (!source.equals(other.source))
				return false;
			if (sourceCode == null) {
				if (other.sourceCode != null)
					return false;
			} else if (!sourceCode.equals(other.sourceCode))
				return false;
			if (stops == null) {
				if (other.stops != null)
					return false;
			} else if (!stops.equals(other.stops))
				return false;
			return true;
		}

	}
	 

[Dave Tolls]

No, that first one is saying you need an equals and hashcode in the RouteId class.
It needs that to ensure that it can tell when one instance of Route is representing the same row as another instance.

For the others errors, what are the primary keys in Airline and Airport?
That is, what are the @Id field(s)?

They fields for the Ids in RouteId need to be of the same type.

[Rob Spoor]

Correct. I assumed they are Longs because that's what I usually use.

I am a bit surprised that the RouteId class can't be final, as all our primary key classes are final. This may be caused by a different Hibernate version though. Easy solution: just remove the final keyword.

It's obvious that your hashCode and equals methods are generated, because only an IDE (Eclipse, right?) can produce such horrors. FYI, here's how I would rewrite that (Java 7+ only):

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + Objects.hashCode(airline);
            result = prime * result + Objects.hashCode(airlineCode);
            result = prime * result + Objects.hashCode(codeshare);
            result = prime * result + Objects.hashCode(destination);
            result = prime * result + Objects.hashCode(destinationCode);
            result = prime * result + Objects.hashCode(equipment);
            result = prime * result + Objects.hashCode(id);
            result = prime * result + Objects.hashCode(source);
            result = prime * result + Objects.hashCode(sourceCode);
            result = prime * result + Objects.hashCode(stops);
            return result;
        }
 
        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null || getClass() != obj.getClass()) {
                return false;
            }
            Route other = (Route) obj;
            return Objects.equals(airline, other.airline)
                    && Objects.equals(airlineCode, other.airlineCode)
                    && Objects.equals(codeshare, other.codeshare)
                    && Objects.equals(destination, other.destination)
                    && Objects.equals(destinationCode, other.destinationCode)
                    && Objects.equals(equipment, other.equipment)
                    && Objects.equals(id, other.id)
                    && Objects.equals(source, other.source)
                    && Objects.equals(sourceCode, other.sourceCode)
                    && Objects.equals(stops, other.stops)
                   ;
        }

[Stephan van Hulst]

Why not:

@Override
public int hashCode() {
  return Objects.hash(
    airline,
    airlineCode,
    codeshare,
    destination,
    destinationCode,
    equipment,
    id,
    source,
    sourceCode,
    stops
  );
}

[Philippe Ponceblanc]

I think I have understood a little, except that I have three errors left, the purpose of which I do not understand.


>> Class Route

@Entity
public class Route {
 
    @EmbeddedId
    private RouteId id;
 
    private String airlineCode;
 
    @ManyToOne // error : The type of the ID mapped by the relationship 'airline' does not agree with the primary key class of the target entity.
    @MapsId("airlineId")
    private Airline airline;
 
    private String sourceCode;
 
    @ManyToOne // error : The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.
    @MapsId("sourceId")
    private Airport source;
      
    private String destinationCode;
      
    @ManyToOne // The type of the ID mapped by the relationship 'destination' does not agree with the primary key class of the target entity.
    @MapsId("destinationId")
    private Airport destination;

>> Class Airline

package flights;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Airline {
	
	@Id
	private int airlineId;
	
	
	private String name;
	
	
	private String alias;
	

	@Column(scale=2)
	private String iata;
	

	private String icao;
	

	private String callsign;
	

	private String country;
	

	private Boolean active;

	
	public int getId() {
		return airlineId;
	}

>> Class Airport

package flights;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Airport {

	
	@Id
	private int id;
	
	
	private String name;
	

	private String city;
	

	private String country;
	

	private String iata;
	
	
	private String icao;
	
	
	private Double latitude;

	
	private Double longitude;
	

	private int altitude;

	
	private Float timezone;
	
	
	private Character daylight;
	
	
	private String tzName;
	
	

	private String source;

>> Class RouteId

package flights;

import java.io.Serializable;

import javax.persistence.Embeddable;

@Embeddable // The Java class for mapped type "flights.RouteId" is final
public class RouteId implements Serializable {
 
    private static final long serialVersionUID = -2403746842148223177L;
 // assuming all Long ids
    private Long airlineId;
    private Long sourceId;
    private Long destinationId;
    
    


      

[Dave Tolls]

Airline and Airport use ints for their ids.
Your RouteId class uses Long.

That's why JPA is complaining about:
The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.

[Philippe Ponceblanc]

Dave Tolls wrote:Airline and Airport use ints for their ids.
Your RouteId class uses Long.

That's why JPA is complaining about:
The type of the ID mapped by the relationship 'source' does not agree with the primary key class of the target entity.

thanks you!

Post/thread Solved

[Rob Spoor]

Stephan van Hulst wrote:Why not:

@Override
public int hashCode() {
  return Objects.hash(
    airline,
    airlineCode,
    codeshare,
    destination,
    destinationCode,
    equipment,
    id,
    source,
    sourceCode,
    stops
  );
}

Simple - it creates one extra array (because of varargs).

[Stephan van Hulst]

I think writing up your last response already took more time than the cumulative total of difference in runtime of all executions of that application.

I doubt the temporary addition of 50-100 bytes on the stack is that much of a big deal either.

[Tim Holloway]

I think you should be using @IdClass. That's what I do, anyway.

[Rob Spoor]

Stephan van Hulst wrote:I doubt the temporary addition of 50-100 bytes on the stack is that much of a big deal either.

If it's on the stack then there is no problem. I thought that the array was created on the heap. That adds garbage collection overhead (and we've had IT OPS breathing down our necks that there was too much GC time). Do you have some article (or the JLS) that shows that vararg arrays are indeed created on the stack?

[Stephan van Hulst]

Well, unless Objects.hash() does weird things with the array, like passing it around to other method calls, escape analysis can determine that the object can be allocated on the stack.

Check out this question on StackOverflow: https://stackoverflow.com/questions/43002528/when-can-hotspot-allocate-objects-on-the-stack

[Rob Spoor]

That makes quite a bit of sense.