我有3个依赖的下拉列表乡村城市路。
在数据库中预先填充的国家并且基于第一个的选择，第二个将显示相关城市。
问题是，一旦用户从第一个下拉列表中选择系统，系统将显示以下错误：
all_cities = selected_country.city_set.all（）attributeError： "国家"对象没有属性" city_set"
我不知道如何解决此错误。
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'id : {0} MouhafazatID :{1} Name :{2}'.format(self.id,self.MouhafazatID,self.name)
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)
home2.html
<html>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"></script>
<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 };
alert(country_name);
$.ajax({
type:"GET",
url:'/getdetails',
// data:JSON.stringify(data),
data:data,
success: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,redirect
from django.http import HttpResponse,JsonResponse
from testapp.models import *
import json as simplejson
def home2(request):
countries = Country.objects.all()
print("countries =", countries)
return render(request, 'home2.html',{'countries': countries})
def getdetails(request):
if request.method == 'GET' and request.is_ajax():
country_name = request.GET.get('cnt', None)
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()
print("cities are: " , all_cities)
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')
# return JsonResponse(result_set,status = 200)
else:
return redirect('/')
如您所见，我正在以JSON格式传递数据。
但是 views.pys.py 中的功能直到该行
执行print ("selected country name ", selected_country)
具有正确的值。
然后显示错误。
访问反向外键关系时，请在提及相关模型时始终使用较低的情况。是
all_cities = selected_country.city_set.all()
要获得更好的可读性，请在声明外键字段时使用related_name属性。示例：
class City(models.Model):
name = models.CharField(max_length=100)
country = models.ForeignKey(Country, on_delete=models.CASCADE, related_name='cities')
通过添加上述related_name属性，您可以访问以下城市：
all_cities = selected_country.cities.all()
您需要用city_set替换City_set，因为使用了较低的情况。