【发布时间】：2019-07-15 00:31:00
【问题描述】：
我是 Django 新手，我正在尝试从数据库中获取数据到一个下拉列表中，其中我有 3 个链接的下拉列表。
当我使用request.GET时，系统显示如下错误：
引发 MultiValueDictKeyError(key) django.utils.datastructures.MultiValueDictKeyError: 'cnt'
追溯
Traceback（最近一次调用最后一次）：文件 "C:\Users\LTGM~1\Desktop\TEST2F~1\test2\lib\site-packages\django\core\handlers\exception.py", 第 34 行，在内部 response = get_response(request) 文件 "C:\Users\LTGM~1\Desktop\TEST2F~1\test2\lib\site-packages\django\core\handlers\base.py", 第 126 行，在 _get_response 中 response = self.process_exception_by_middleware(e, request) 文件 "C:\Users\LTGM~1\Desktop\TEST2F~1\test2\lib\site-packages\django\core\handlers\base.py", 第 124 行，在 _get_response response = Wrapped_callback(request, *callback_args, **callback_kwargs) 文件“C:\Users\LT GM\Desktop\test2ForImportExport\test2\testpro\views.py”，第 23 行，在 获取详细信息 country_name = request.GET['cnt'] 文件 "C:\Users\LTGM~1\Desktop\TEST2F~1\test2\lib\site-packages\django\utils\datastructures.py", 第 79 行，在 getitem 中 引发 MultiValueDictKeyError(key) django.utils.datastructures.MultiValueDictKeyError: 'cnt' [21/Feb/2019 09:02:28]“GET /getdetails/HTTP/1.1”500 15859
models.py
class country(models.Model):
name = models.CharField(max_length=100)
def __str__(self):
return str(self.name)
class city(models.Model):
name = models.CharField(max_length=100)
country = models.ForeignKey(country,on_delete=models.CASCADE)
def __str__(self):
return str(self.name)
class road(models.Model):
Vil = models.CharField(max_length=100)
city= models.ForeignKey(city,on_delete = models.SET_NULL, null=True)
country= models.ForeignKey(country,on_delete = models.SET_NULL,null=True)
def __str__(self):
return str(self.Vil)
urls.py
from django.contrib import admin
from django.urls import path, include
from.views import *
urlpatterns = [
path('admin/', admin.site.urls),
path('', home2),
path('getdetails/', getdetails),
home2.html
<script>
$(document).ready(function(){
$('select#selectcountries').change(function () {
var optionSelected = $(this).find("option:selected");
var valueSelected = optionSelected.val();
var country_name = optionSelected.text();
data = {'cnt' : country_name };
$.ajax('/getdetails',data,function(result){
console.log(result);
$("#selectcities option").remove();
for (var i = result.length - 1; i >= 0; i--) {
$("#selectcities").append('<option>'+ result[i].name +'</option>');
};
});
});
});
</script>
</head>
<body>
<select name="selectcountries" id="selectcountries">
{% for item in countries %}
<option val="{{ item.name }}"> {{ item.name }} </option>
{% endfor %}
</select>
<select name ="selectcities" id="selectcities">
</select>
<select name ="selectroads" id="selectroads">
</select>
</body>
</html>
views.py
from django.shortcuts import render
from django.http import HttpResponse
from testapp.models import *
import json as simplejson
def home2(request):
countries = country.objects.all()
print(countries)
return render(request, 'home2.html',{'countries': countries})
def getdetails(request):
country_name = request.GET['cnt'] # here is the error
print ("ajax country_name ", country_name)
result_set = []
all_cities = []
answer = str(country_name[1:-1])
print('answer = ' ,answer)
selected_country = country.objects.get(name=answer)
print ("selected country name ", selected_country)
all_cities = selected_country.city_set.all()
for city in all_cities:
print ("city name", city.name)
result_set.append({'name': city.name})
return HttpResponse(simplejson.dumps(result_set),content_type='application/json')
我期望的是，一旦用户从第一个下拉列表中选择，第二个下拉列表将只显示属于第一个选择的数据。
【问题讨论】：