PrimitiveApes

_{Team Page}

Database

Database contains multiple tables for Student info and notes

@ManyToOne
  @JoinColumn(name="student_id")
  private Student student;

Annotations used to achieve Many-to-One relation: each Student POJO has multiple corresponding Note POJOs

@NonNull
    @Size(min = 1, message = "Name")
    private String name;

    private int table_number;


    private int period;

    /* Initializer used when setting data from an API */
    public Student(String name, int table_number, int period_number) {
        this.table_number = table_number;
        this.name = name;
        this.period = period_number;
    }

Student POJO contains name, table number, and period. The constructor is used when saving entries to the database

Student student = modelRepository.get(id);
        List<Note> notes = noteRepository.findAllByStudent(student);
        Note note = new Note();
        note.setStudent(student);

        for (Note n : notes)
            n.setText(n.getText());
            
            @PostMapping("/database/notes")
    public String notesAdd(@Valid Note note, BindingResult bindingResult) {
        // back to person ID on redirect
        String redirect = "redirect:/database/notes/"+note.getStudent().getId();

        // database errors
        if (bindingResult.hasErrors()) {
            return redirect;
        }

        // note is saved and person ID is pre-set
        noteRepository.save(note);

Notes controller finds the student matching the id and then uses the findAllByStudent method with a Student object as a parameter to output a list of Notes object corresponding to that Student
For loop iterates through each of these notes and set’s the text variable
Post-Mapping: HTML form submits a Notes object, which is combined with JPA repository save method to add to the database

public  List<Student>listAll() {
        return jpa.findAll();
    }


    public  List<Student>listLikeNative(String term) {
        String like_term = String.format("%%%s%%",term);  // Like required % rappers
        return jpa.findByLikeTermNative(like_term);
    }

    public void save(Student student) {
        jpa.save(student);

    }

    public Student get(long id) {
        return (jpa.findById(id).isPresent())
                ? jpa.findById(id).get()
                : null;
    }

    public void delete(long id) {
        jpa.deleteById(id);
    }

Different CRUD methods used to add, update, and delete entries from the database

<tbody>
                    <tr th:each="student : ${list}">
                        <td th:text="${student.id}"> ID</td>
                        <td th:text="${student.name}"> Name</td>
                        <td th:text="${student.table_number}">Table</td>
                        <td th:text="${student.period}">Period</td>

                        <td>
                            <a th:href="@{/database/student_update/{id}(id = ${student.id})}">Update</a>
                            <a th:href="@{/database/student_delete/{id}(id = ${student.id})}">Delete</a>
                            <a th:href="@{/database/notes/{id}(id = ${student.id})}">Notes</a>
                        </td>
                    </tr>

                    </tbody>

Thymeleaf table is generated by using th:each to iterate through the list of Student objects returned through the controller, each row prints a different variable from the Student POJO
Links to the right redirect to pages for updating and deleting student, as well as adding Notes, using the student id as part of the url

Randomization Algorithm

sets studentsPerTable = numStudents/numTables, and then randomly adds students to table groups by creating Student objects with their table # and a random student name from the names list. Removes names from names list so that students can not be added to multiple groups.

        studentsPerTable = numStudents / numTables;

        for (int i = 0; i < numTables; i++) {
            for (int j = 0; j < studentsPerTable; j++) {
                int index = (int) (Math.random() * names.size());
                StudentObject oneStudent = new StudentObject(i, names.get(index));
                groups.add(oneStudent);
                names.remove(index);
            }
        }

To deal with the case that numStudents is not divisble by numTables, we check that names is not empty (or names.size() > 0), and add the remaining students randomly to table 0 -> table n.

        int i = 0;
            while(names.size() > 0 && i < numTables){
                int index = (int) (Math.random() * names.size());
                StudentObject oneStudent = new StudentObject(i, names.get(index));
                groups.add(oneStudent);
                names.remove(index);
                i++;
            }

        return groups;

After doing this, though, the students may not ordered by their table group. Thus, I implemented a selection sort in order to ensure that students within the same table are next to oneanother inside the arraylist.

public static void sort(ArrayList<StudentObject> a){
        int n = a.size();

        for(int i =0;i < n-1; i++){
            int min_idx = i;
            for(int j = i+1; j < n; j++){
                if(a.get(j).getTableGroup() < a.get(min_idx).getTableGroup()){
                    min_idx = j;
                }
            }
            StudentObject temp = a.get(min_idx);
            a.set(min_idx, a.get(i));
            a.set(i, temp);
        }
    }