Django 选择如何记住所选值？

问：

我有一个选择。在项目更改时，我重新加载了一个页面，但在重新加载后，我选择了一个空白项目。如何记住所选项目？

teacher.html

<form id="form"  method="POST">{% csrf_token %}
       <select name="choose_teacher" onChange="this.form.submit();" blank_choice='Please choose:' >
       <option value="{{ 0 }}">blank</option>
           {% for item in query_results %}
               <option value="{{ item.id }}">{{ item.title}} {{ item.name }} {{ item.surname }}</option>
           {% endfor %}
       </select>
</form>
{{ teacher_id }}

views.py

def teacher(request):
if request.method == 'POST':
    if 'choose_teacher' in request.POST:
        teacher_id = request.POST['choose_teacher']
        query_results = Teacher.objects.all()
        context = {'teacher_id': teacher_id,
                   'query_results': query_results}
        return render(request, 'planner/teacher.html', context)
else:
    query_results = Teacher.objects.all()
    context = {'query_results': query_results}
    return render(request, 'planner/teacher.html', context)

：编辑：

    <form id="form" method="POST">{% csrf_token %}
    <select name="choose_teacher" onChange="this.form.submit();">
        {% for item in query_results %}
            <option value="{{ item.id }}"
                    {% ifequal teacher_id item.id %}selected{% endifequal %}>{{ item.title }} {{ item.name }} {{ item.surname }}</option>
        {% endfor %}
    </select>
</form>