diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Adoptions.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Adoptions.java
index 5f97e86..f397141 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Adoptions.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Adoptions.java
@@ -1,8 +1,5 @@
 package cat.udl.eps.softarch.demo.domain;
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.Id;
-import jakarta.persistence.OneToOne;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import lombok.Data;
@@ -22,7 +19,7 @@
 public class Adoptions {
 
     @Id
-    @GeneratedValue
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
     @OneToOne
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Permission.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Permission.java
index 53e4c36..b1fc8ff 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Permission.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Permission.java
@@ -1,6 +1,8 @@
 package cat.udl.eps.softarch.demo.domain;
 
 import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
@@ -13,6 +15,7 @@
 public class Permission {
 
     @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
     @NotNull
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
index cafe8ed..97e5bea 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Pet.java
@@ -1,10 +1,7 @@
 package cat.udl.eps.softarch.demo.domain;
 
 import com.fasterxml.jackson.annotation.JsonIdentityReference;
-import jakarta.persistence.Entity;
-import jakarta.persistence.Id;
-import jakarta.persistence.ManyToOne;
-import jakarta.persistence.OneToOne;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import lombok.AllArgsConstructor;
@@ -22,6 +19,7 @@
 public abstract class Pet extends UriEntity<Long> {
 
     @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
     @NotBlank
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Role.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Role.java
index ed51a2f..f0d6346 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Role.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Role.java
@@ -1,8 +1,6 @@
 package cat.udl.eps.softarch.demo.domain;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.Id;
-import jakarta.persistence.Table;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.NotBlank;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
@@ -11,10 +9,11 @@
 @Table(name = "Role") // Nombre de la tabla en la base de datos
 @Data
 @EqualsAndHashCode(callSuper = true)
-public class Role extends UriEntity<String> {
+public class Role extends UriEntity<Long> {
 
     @Id
-    private String id;
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
 
     @NotBlank
     private String name;
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Schedule.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Schedule.java
index 34a5fb6..19b34fa 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Schedule.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Schedule.java
@@ -2,10 +2,7 @@
 
 
 import com.fasterxml.jackson.annotation.JsonIdentityReference;
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.Id;
-import jakarta.persistence.ManyToOne;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.NotNull;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
@@ -18,7 +15,7 @@
 public class Schedule {
 
     @Id
-    @GeneratedValue
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private int Id;
 
     @NotNull
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/Shelter.java b/src/main/java/cat/udl/eps/softarch/demo/domain/Shelter.java
index 2c8eb0d..725876e 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/Shelter.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/Shelter.java
@@ -1,16 +1,14 @@
 package cat.udl.eps.softarch.demo.domain;
 
-import jakarta.persistence.Column;
-import jakarta.persistence.Entity;
-import jakarta.validation.constraints.NotNull;
-import jakarta.validation.constraints.Pattern;
-import lombok.Data;
-import jakarta.persistence.Id;
+import com.fasterxml.jackson.annotation.JsonIdentityReference;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.Email;
 import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Pattern;
 import jdk.jfr.BooleanFlag;
+import lombok.Data;
 import lombok.EqualsAndHashCode;
-import org.hibernate.validator.constraints.Length;
 
 import java.time.LocalDateTime;
 
@@ -19,7 +17,23 @@
 @EqualsAndHashCode(callSuper = false)
 public class Shelter extends UriEntity<Long> {
 
+    @ManyToOne
+    @NotNull
+    @JsonIdentityReference(alwaysAsId = true)
+    private User user;
+
+    @ManyToOne
+    @NotNull
+    @JsonIdentityReference(alwaysAsId = true)
+    private Pet pet;
+
+    @OneToOne
+    @NotNull
+    @JsonIdentityReference(alwaysAsId = true)
+    private ShelterCertificate shelterCertificate;
+
     @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
     @NotBlank
diff --git a/src/main/java/cat/udl/eps/softarch/demo/domain/ShelterCertificate.java b/src/main/java/cat/udl/eps/softarch/demo/domain/ShelterCertificate.java
index 730f2d4..9d50754 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/domain/ShelterCertificate.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/domain/ShelterCertificate.java
@@ -1,9 +1,7 @@
 package cat.udl.eps.softarch.demo.domain;
 
 import com.fasterxml.jackson.annotation.JsonIdentityReference;
-import jakarta.persistence.Entity;
-import jakarta.persistence.Id;
-import jakarta.persistence.OneToOne;
+import jakarta.persistence.*;
 import jakarta.validation.constraints.NotNull;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
@@ -20,6 +18,7 @@ public class ShelterCertificate {
     private Shelter shelter;
 
     @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
 
     @NotNull
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/AdoptionsRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/AdoptionsRepository.java
index 5101d0b..cdc69fb 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/AdoptionsRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/AdoptionsRepository.java
@@ -3,6 +3,8 @@
 import cat.udl.eps.softarch.demo.domain.Adoptions;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface AdoptionsRepository extends CrudRepository<Adoptions, String>, PagingAndSortingRepository<Adoptions, String> {
+@RepositoryRestResource
+public interface AdoptionsRepository extends CrudRepository<Adoptions, Long>, PagingAndSortingRepository<Adoptions, Long> {
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/CatRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/CatRepository.java
index 48c8445..e92592a 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/CatRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/CatRepository.java
@@ -3,6 +3,8 @@
 import cat.udl.eps.softarch.demo.domain.Cat;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface CatRepository extends CrudRepository<Cat, String>, PagingAndSortingRepository<Cat, String> {
+@RepositoryRestResource
+public interface CatRepository extends CrudRepository<Cat, Long>, PagingAndSortingRepository<Cat, Long> {
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/DogRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/DogRepository.java
index 5e83b4c..e068275 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/DogRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/DogRepository.java
@@ -3,6 +3,8 @@
 import cat.udl.eps.softarch.demo.domain.Dog;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface DogRepository extends CrudRepository<Dog, String>, PagingAndSortingRepository<Dog, String> {
+@RepositoryRestResource
+public interface DogRepository extends CrudRepository<Dog, Long>, PagingAndSortingRepository<Dog, Long> {
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/LocationRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/LocationRepository.java
index ea42215..e705bd3 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/LocationRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/LocationRepository.java
@@ -4,8 +4,10 @@
 import cat.udl.eps.softarch.demo.domain.User;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface LocationRepository extends CrudRepository<Location, String>, PagingAndSortingRepository<Location, String> {
+@RepositoryRestResource
+public interface LocationRepository extends CrudRepository<Location, Long>, PagingAndSortingRepository<Location, Long> {
 
 
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java
index d7edc69..0e4cbc5 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/PetRepository.java
@@ -3,6 +3,8 @@
 import cat.udl.eps.softarch.demo.domain.Pet;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface PetRepository extends CrudRepository<Pet, String>, PagingAndSortingRepository<Pet, String> {
+@RepositoryRestResource
+public interface PetRepository extends CrudRepository<Pet, Long>, PagingAndSortingRepository<Pet, Long> {
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/ScheduleRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/ScheduleRepository.java
index 9f7555f..aa60082 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/ScheduleRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/ScheduleRepository.java
@@ -3,7 +3,9 @@
 import cat.udl.eps.softarch.demo.domain.Schedule;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface ScheduleRepository extends CrudRepository<Schedule, String>, PagingAndSortingRepository<Schedule, String> {
+@RepositoryRestResource
+public interface ScheduleRepository extends CrudRepository<Schedule, Long>, PagingAndSortingRepository<Schedule, Long> {
     
 }
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterCertificateRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterCertificateRepository.java
index 37f578f..a56fbc5 100644
--- a/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterCertificateRepository.java
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterCertificateRepository.java
@@ -3,7 +3,9 @@
 import cat.udl.eps.softarch.demo.domain.ShelterCertificate;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 
-public interface ShelterCertificateRepository extends CrudRepository<ShelterCertificate, String>, PagingAndSortingRepository<ShelterCertificate, String> {
+@RepositoryRestResource
+public interface ShelterCertificateRepository extends CrudRepository<ShelterCertificate, Long>, PagingAndSortingRepository<ShelterCertificate, Long> {
 
 }
\ No newline at end of file
diff --git a/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterRepository.java b/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterRepository.java
new file mode 100644
index 0000000..78b6dc1
--- /dev/null
+++ b/src/main/java/cat/udl/eps/softarch/demo/repository/ShelterRepository.java
@@ -0,0 +1,11 @@
+package cat.udl.eps.softarch.demo.repository;
+
+import cat.udl.eps.softarch.demo.domain.Shelter;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
+
+@RepositoryRestResource
+public interface ShelterRepository extends CrudRepository<Shelter, Long>, PagingAndSortingRepository<Shelter, Long> {
+
+}
\ No newline at end of file