Removing a project assignment

P/Sda1/Jpa/Company/companyJpa1/src/main/java/de/hdm_stuttgart/mi/company/model/Employee.java

@@ -30,7 +30,32 @@ public class Employee {
 	
 	String name, email;
 	
-	@OneToMany(mappedBy="employee", cascade=CascadeType.PERSIST)
+	@OneToMany(mappedBy="employee", cascade=CascadeType.ALL)
 	Set<WorksFor> projects = new HashSet<WorksFor>();
 
+   public Long getId() { return id;}
+
+   public String getName() {
+      return name;
+   }
+
+   public void setName(String name) {
+      this.name = name;
+   }
+
+   public String getEmail() {
+      return email;
+   }
+
+   public void setEmail(String email) {
+      this.email = email;
+   }
+
+   public Set<WorksFor> getProjects() {
+      return projects;
+   }
+
+   public void setProjects(Set<WorksFor> projects) {
+      this.projects = projects;
+   }
 }

P/Sda1/Jpa/Company/companyJpa1/src/main/java/de/hdm_stuttgart/mi/company/model/Project.java

@@ -31,7 +31,7 @@ public class Project {
 	
 	String name;
 	
-	@OneToMany(mappedBy="project", cascade=CascadeType.PERSIST)
+	@OneToMany(mappedBy="project", cascade=CascadeType.ALL)
 	Set<WorksFor> employees = new HashSet<WorksFor>();
 
 	public String getName() {

P/Sda1/Jpa/Company/companyJpa1/src/main/java/de/hdm_stuttgart/mi/company/model/WorksFor.java

@@ -5,6 +5,8 @@ import javax.persistence.Entity;
 import javax.persistence.Id;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
+import javax.persistence.PostRemove;
+import javax.persistence.PreRemove;
 import javax.persistence.Table;
 import javax.persistence.UniqueConstraint;
 
@@ -40,11 +42,14 @@ public class WorksFor {
 	}
 
 	public void setProject(Project project) {
-		if (null != this.project && this.project != project ) {
-			this.project.employees.remove(this);
-		}
-		this.project = project;
-		project.employees.add(this);
+	   if (null == this.project) {
+	      this.project = project;
+	      project.employees.add(this);
+	   } else if (this.project != project) {
+         this.project.employees.remove(this);
+         this.project = project;
+         project.employees.add(this);
+	   }
 	}
 
 	public Employee getEmployee() {
@@ -67,5 +72,16 @@ public class WorksFor {
 		this.weekly_hours = weekly_hours;
 	}
 	
+	@PreRemove
+	void preRemove() {
+	   project.getEmployees().remove(this);
+	   employee.getProjects().remove(this);
+	}
+	@PostRemove
+	void postRemove() {
+	   project = null;
+	   employee = null;
+	   weekly_hours = 0;
+	}
 	
 }

P/Sda1/Jpa/Company/companyJpa1/src/test/java/de/hdm_stuttgart/mi/company/DeleteProjectAssignment.java

+package de.hdm_stuttgart.mi.company;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.EntityTransaction;
+import javax.persistence.Persistence;
+
+import org.junit.Test;
+
+import de.hdm_stuttgart.mi.company.model.Employee;
+import de.hdm_stuttgart.mi.company.model.Project;
+import de.hdm_stuttgart.mi.company.model.WorksFor;
+
+/**
+ * Assigning a user to a project and releasing the assignment
+ * in a second transaction.
+ *
+ */
+public class DeleteProjectAssignment {
+
+   static final EntityManager em;
+
+   static {
+      final EntityManagerFactory emFactory =  Persistence.createEntityManagerFactory("create-drop");
+      em = emFactory.createEntityManager();
+   }
+
+   @Test
+   public void createDropAssignment() {
+
+      Long jimId;
+      {
+         final EntityTransaction transaction = em.getTransaction();
+         transaction.begin();
+
+         final Project bridge = new Project("Bridge");
+
+         final Employee jim = new Employee("Jom Bone", "bone@graveyard.com");
+
+         new WorksFor(bridge, jim, 13);
+
+         em.persist(bridge);
+         transaction.commit();
+
+         jimId = jim.getId();
+
+      }
+
+      {
+         final EntityTransaction transaction = em.getTransaction();
+         transaction.begin();
+
+         final Employee jim = em.find(Employee.class, jimId);
+
+         for (WorksFor wf: jim.getProjects()) {
+            em.remove(wf);
+         }
+         
+         transaction.commit();
+      }
+   }
+}
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