API Object removal improved

src/main/java/de/igslandstuhl/database/api/SchoolClass.java

@@ -162,6 +162,14 @@ public List<Student> getStudents() {
 
     public void delete() throws SQLException {
         Server.getInstance().getConnection().executeVoidProcessSecure(SQLHelper.getDeleteObjectProcess("class", String.valueOf(id)));
+        getStudents().forEach((s) -> {
+            try {
+                s.delete();
+            } catch (SQLException e) {
+                e.printStackTrace();
+                throw new IllegalStateException(e);
+            }
+        });
     }
 
     /**

src/main/java/de/igslandstuhl/database/api/Student.java

@@ -461,6 +461,11 @@ public void clearSubjectRequest(int subjectId) {
         currentRequests.remove(subjectId);
     }
 
+    public void delete() throws SQLException {
+        Server.getInstance().getConnection().executeVoidProcessSecure(SQLHelper.getDeleteObjectProcess("student", String.valueOf(id)));
+        students.remove(id);
+    }
+
     @Override
     public String toString() {
         return toJSON();

src/main/java/de/igslandstuhl/database/api/Subject.java

@@ -2,6 +2,7 @@
 
 import java.sql.SQLException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -236,6 +237,22 @@ public void delete() throws SQLException {
             SQLHelper.getDeleteObjectProcess("subject", String.valueOf(id))
         );
         subjects.remove(id);
+        try {
+            Arrays.stream(getGrades()).mapToObj(this::getTopics).forEach((l) -> l.forEach((t) -> {
+                try {
+                    t.delete();
+                } catch (SQLException e) {
+                    e.printStackTrace();
+                    throw new IllegalStateException(e);
+                }
+            }));
+        } catch (IllegalStateException e) {
+            if (e.getCause() != null && e.getCause() instanceof SQLException ex) {
+                throw ex;
+            } else {
+                throw e;
+            }
+        }
     }
 
     @Override

src/main/java/de/igslandstuhl/database/api/Task.java

@@ -147,6 +147,11 @@ public void removeFromCache() {
         tasks.remove(id);
     }
 
+    public void delete() throws SQLException {
+        Server.getInstance().getConnection().executeVoidProcessSecure(SQLHelper.getDeleteObjectProcess("task", String.valueOf(id)));
+        removeFromCache();
+    }
+
     /**
      * Creates a Task object from SQL query result fields.
      *

src/main/java/de/igslandstuhl/database/api/Topic.java

@@ -322,7 +322,13 @@ public static Topic addTopic(String name, Subject subject, int ratio, int grade,
     public void delete() throws SQLException {
         Server.getInstance().getConnection().executeVoidProcessSecure(SQLHelper.getDeleteObjectProcess("topic", String.valueOf(id)));
         topics.remove(id);
-        tasks.forEach(Task::removeFromCache);
+        tasks.forEach(t -> {
+            try {
+                t.delete();
+            } catch (SQLException e) {
+                throw new IllegalStateException(e);
+            }
+        });
     }
 
     @Override

src/main/resources/sql/pushes/delete_student.sql

@@ -0,0 +1,2 @@
+DELETE FROM students
+WHERE id = {0}

src/main/resources/sql/pushes/delete_task.sql

@@ -0,0 +1,2 @@
+DELETE FROM tasks
+WHERE id = {0}