Add the relationship between the models.

src/main/java/space/kklochko/jpa_hospital_example/models/Department.java

@@ -4,6 +4,7 @@ import jakarta.persistence.*;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 
+import java.util.List;
 import java.util.UUID;
 
 @Table(name="departments")
@@ -18,6 +19,9 @@ public class Department {
     String location;
     String phone;
 
+    @OneToMany(cascade = CascadeType.ALL, mappedBy="department")
+    private List<Patient> patients;
+
     public Department(){
         setId(UUID.randomUUID());
         setName("");
@@ -31,5 +35,12 @@ public class Department {
         setLocation(location);
         setPhone(phone);
     }
+
+    public Department(UUID id, String name, String location, String phone){
+        setId(id);
+        setName(name);
+        setLocation(location);
+        setPhone(phone);
+    }
 }
 

src/main/java/space/kklochko/jpa_hospital_example/models/Indicator.java

@@ -14,10 +14,13 @@ import java.util.UUID;
 public class Indicator {
     @Id
     @Column(nullable = true)
-    UUID id;
+    private UUID id;
-    String type;
+    private String type;
-    String values;
+    private String values;
-    Timestamp timestamp;
+    private Timestamp timestamp;
+
+    @ManyToOne
+    private Patient patient;
 
     public Indicator(){
         setId(UUID.randomUUID());
@@ -32,5 +35,12 @@ public class Indicator {
         setValues(values);
         setTimestamp(timestamp);
     }
+
+    public Indicator(UUID id, String type, String values, Timestamp timestamp){
+        setId(id);
+        setType(type);
+        setValues(values);
+        setTimestamp(timestamp);
+    }
 }
 

src/main/java/space/kklochko/jpa_hospital_example/models/Patient.java

@@ -4,19 +4,26 @@ import jakarta.persistence.*;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 
-import java.util.ArrayList;
+import java.util.List;
 import java.util.UUID;
 
 @Table(name="patients")
 @Entity
+@AllArgsConstructor
 @Data
 public class Patient {
     @Id
     @Column(nullable = true)
-    UUID id;
+    private UUID id;
-    String name;
+    private String name;
-    short age;
+    private short age;
-    String phone;
+    private String phone;
+
+    @OneToMany(cascade = CascadeType.ALL, mappedBy="patient")
+    private List<Indicator> indicators;
+
+    @ManyToOne
+    private Department department;
 
     public Patient() {
         setId(UUID.randomUUID());