Как найти уровень оценки и тип оплаты для уровня класса и предмета, используя два варианта выбора?

Question

    \\html
     <form  method="post" action="/newEnroll/">
     {% csrf_token %}
     <table>
       <tr>
          <td></td>
          <td>
              <input type=submit value="submit" id="enroll" class="enroll" formaction="/newEnroll/"> 
          </td>
          <td>
              <input type='button' name='back' value='Back' class='button' onclick="history.back()" /> 
          </td>
        </tr>
     </table>
     <form action="" method="get">
          {% csrf_token %}
     <select name="gradelevel" id="gradelevel">
         <option value="0">-- EducationLevel --</option>
         {% for ylvl in edulevel %}
         <option value="{{ylvl.id}}" name="gradelevel" >{{ylvl.Description}}</option>
         {% endfor %}
     </select>
     <select  name="paymentID" id="paymentID" required="required">
          <option name="NULL" value="0" >----Payment Type----</option>
          {% for pay in payment %}
          <option name="paymentID" value="{{pay.id}}" >{{pay.Description}}</option>
          {% endfor %}
     </select>
     <input type="submit"  value="View" onchange="showResult(this.value)" id="showTxt" formaction="">
     </form>
     <div id="paymentshow">
         <tr><th>Subject</th></tr>
         <tr>
         </tr>
         {% for sub in subj %}
         <tr>
         <td>{{sub.Description}}</td>
         </tr>
         {% endfor %}
         <tr><th>Payment Type</th></tr>
         {% for schedule in sched %}
         <tr>
         <td>{{schedule.Remark}}</td>
         <td>Php {{ schedule.Amount|floatformat:2}}</td>
         </tr>
         {% endfor %}
         </form>
</form>
</body>
<script>
function showResult(subj) {
var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
     if (this.readyState == 4 && this.status == 200) {
        document.getElementById("txtHint").innerHTML = this.responseText;
        }
    };
xhttp.open("POST", "{% url 'enrollmentform' %}?gradelevel="+subj, true);
xhttp.send();
}
</script>

<script>
function payment(str) {
var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function() {
     if (this.readyState == 4 && this.status == 200) {
        document.getElementById("paymentshow").innerHTML = this.responseText;
        }
    };
xhttp.open("POST", "{% url 'searchpayment' %}?payment="+str, true);
xhttp.send();
}
</script>
\\views
    paymentID = request.POST.get('paymentID')
    sched = ScheduleOfPayment.objects.all().filter(Payment_Type=paymentID).filter(Education_Levels=gradelevel)
     \\models
class ScheduleOfPayment(models.Model):
    Education_Levels= models.ForeignKey(EducationLevel, related_name='+', on_delete=models.CASCADE, blank=True, null=True)
    Courses = models.ForeignKey(Course, related_name='+', on_delete=models.CASCADE,blank=True, null=True)
    Payment_Type = models.ForeignKey(PaymentType, related_name='+', on_delete=models.CASCADE, blank=True, null=True)
    Month_Name = models.ForeignKey(MonthName, related_name='+', on_delete=models.CASCADE, blank=True, null=True)
    Display_Sequence = models.IntegerField(blank=True, null=True)
    Day = models.CharField(max_length=500, blank=True, null=True)
    Remark = models.CharField(max_length=500,blank=True, null=True)
    def __str__(self):
        suser = '{0.Education_Levels}'
        return suser.format(self)
class Subject(models.Model):
        Education_Levels= models.ForeignKey(EducationLevel, related_name='+', on_delete=models.CASCADE,blank=True)
        Courses = models.ForeignKey(Course, related_name='+', on_delete=models.CASCADE, null=True,blank=True)
        Display_Sequence = models.IntegerField(null=True, blank=True)
        SubjectID_Prerequisite = models.IntegerField(null=True, blank=True)
        Description = models.CharField(max_length=500,blank=True)
        Units = models.FloatField(null=True,blank=True)
        def __str__(self):
           suser = '{0.Description}'
           return suser.format(self)

Я просто хочу отобразить тему и тип оплаты для каждого класса, и я не знаю, правильно ли я поступаю в своем коде.пожалуйста, помогите мне .. я действительно не понимаю фильтр вещь ... Я уже прочитал Документ Django, но я все еще не понимаю.я начал на прошлой неделе учиться и создать какой-то проект с использованием фреймворка django.