我是django的新手。我正在使用简单的ajax 根据 课程* 选择动态更新选择领域 学期 。但是在提交表格时，我收到错误消息，请
选择一个有效的选择。 所选选项 不是可用选项之一。 代码如下： __*

forms.py：

from django import forms
from feedback_form.models import course,section_info

class loginForm(forms.Form):
     iquery1 = course.objects.values_list('course_name', flat = True)
     iquery1_choices = [('', '----------')] + [(id, id) for id in iquery1]
     sem_choices = [('', '----------')]

     course_name = forms.ChoiceField(iquery1_choices,required=True, widget=forms.Select())
     semester = forms.ChoiceField(sem_choices, required= True, widget=forms.Select())

views.py：

def get_batch(request, c_id):
    current_course = feedback_form.models.course.objects.get(course_name=c_id)
    batches = feedback_form.models.batch.objects.all().filter(course_id=current_course)
    no_of_sem = feedback_form.models.course.objects.values_list('number_of_sem', flat=True).filter(course_id = current_course)
    no_of_sem = int(no_of_sem[0])
    batch_dict = {}
    for batch in batches:
         batch_dict[batch.batch_id] = batch.batch_id
    sem = {}
         sem[no_of_sem] = no_of_sem
    data = [batch_dict, no_of_sem]
    return HttpResponse(json.dumps(data))

loginForm.html：

 <form action="" method="post">
    <table>
        {{ form.as_table }}
    </table>
    {% csrf_token%}
    <input type="submit" value="Submit">
 </form>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script>

$(document).ready(function(){
$('#id_course_name').change(function() {
    request_url = 'login/get_batch/' + c_id + '/';
    $.ajax({
        url: request_url,
        success: function(data){
            data = $.parseJSON(data);
            $('#id_semester').html('<option selected="' + "selected" + '">' + '' +'</option>');
            for(var i = 1; i<=data[1]; i++) //data[1] contains no of sem
                $('#id_semester').append('<option value="' + i + '">' + i +'</option>');
        }, 
        errors: function(e) {
            alert(e);
        }
    })

})

请帮帮我。