分配之前引用的django局部变量't' [英] django local variable 't' referenced before assignment
问题描述
我看到这是一个常见错误，我确实浏览了其他帖子，但是他们没有帮助我.
I saw this was a common error and I did look through other post, but they did not help me.
我遇到错误
Exception Value: local variable 't' referenced before assignment
但是在我的if验证中，我的t变量被声明不在上面三行.范围应该可以让我退货.
But my t variable is declared 3 lines above where it is saying it is not, inside my if validation. Scope should be fine for my return.
有问题的功能
def create(response):
#response.user
if response.method == "POST":
form = CreateNewTrade(response.POST)
if form.is_valid():
n = form.cleaned_data["name"]
t = AssetList(name=n)
t.save()
response.user.assetlist.add(t)
return HttpResponseRedirect("/userdash/%i" %t.id) #we fail at this t variable
完整代码:
$ cat userdash/views.py
$ cat userdash/views.py
from django.shortcuts import render
from django.http import HttpResponse, HttpResponseRedirect
from .models import AssetList, Items
from .forms import CreateNewTrade
# Create your views here.
#def index(response):
# return HttpResponse("<h1>Hello Dark World!</h1>")
def userdash(response, id):
ls = AssetList.objects.get(id=id)
if response.method == "POST":
print(response.POST)
if response.POST.get("save"):
for item in ls.items_set.all():
if response.POST.get("c" + str(item.id)) == "clicked":
item.sell_asset = True
else:
item.sell_asset = False
item.save()
elif response.POST.get("newItem"):
txt = response.POST.get("new")
if len(txt) > 2: #this validation is retarded and needs to be fixed
ls.items_set.create(user_asset=txt, sell_asset=False)
else:
print("invalid")
#items = ls.items_set.get(id=1)
#return HttpResponse("<h1>User Dashboard!</h1><h2>%s</h2><br></br><p>%s</p>" %(ls.name, str(items.user_asset)))
return render(response, "userdash/list.html", {"ls":ls})
def home(response):
#pass
return render(response, "userdash/home.html", {})
def create(response):
#response.user
if response.method == "POST":
form = CreateNewTrade(response.POST)
if form.is_valid():
n = form.cleaned_data["name"]
t = AssetList(name=n)
t.save()
response.user.assetlist.add(t)
return HttpResponseRedirect("/userdash/%i" %t.id)
else:
form = CreateNewTrade()
return render(response, "userdash/create.html", {"form":form})
def view(response):
return render(response, "userdash/view.html", {})
$ cat userdash/models.py
$ cat userdash/models.py
from django.db import models
from django.contrib.auth.models import User
# Create your models here.
class AssetList(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="assetlist", null=True)
name = models.CharField(max_length=200)
def __str__(self):
return self.name
class Items(models.Model):
assetlist = models.ForeignKey(AssetList, on_delete=models.CASCADE)
user_asset = models.CharField(max_length=300)
sell_asset = models.BooleanField()
def __str__(self):
return self.user_asset
$ cat userdash/templates/userdash/view.html
$ cat userdash/templates/userdash/view.html
{% extends 'userdash/base.html' %}
{% block title %} View page {% endblock %}
{% load crispy_forms_tags %}
{% block content %}
{% for td in user.assetlist.all %}
<p><a href="/{{td.id}}">{{td.name}}</a></p>
{% endfor %}
{% endblock %}
错误:
UnboundLocalError at /create/
local variable 't' referenced before assignment
Request Method: POST
Request URL: http://192.168.42.14:8081/create/
Django Version: 3.0.5
Exception Type: UnboundLocalError
Exception Value:
local variable 't' referenced before assignment
Exception Location: ./userdash/views.py in create, line 51
Python Executable: /usr/local/bin/uwsgi
Python Version: 3.7.3
Python Path:
['.',
'',
'/home/piggy/Env/lib/python37.zip',
'/home/piggy/Env/lib/python3.7',
'/home/piggy/Env/lib/python3.7/lib-dynload',
'/usr/lib/python3.7',
'/home/piggy/Env/lib/python3.7/site-packages']
如何分配我的t变量，以便我的return语句接受它?
How do I assign my t variable so my return statement will accept it?
推荐答案
这是因为您的表格无效.因此，它将直接转到未定义 t 的返回 HttpResponseRedirect 部分.
It is because your form is not valid. So, it will directly go to the return HttpResponseRedirect part, where t is not defined.
def create(response):
if response.method == "POST":
form = CreateNewTrade(response.POST)
# Because form.is_valid() failed, t will be undefined
if form.is_valid():
n = form.cleaned_data["name"]
# Here only, you have assigned value of t
t = AssetList(name=n)
t.save()
response.user.assetlist.add(t)
# Returns directly to this line, if you see indentation, t is not defined
return HttpResponseRedirect("/userdash/%i" %t.id)
请参阅上面的评论以了解发生了什么.因此，可能的错误减少器可能是:
See comments above to understand what's going on. So, possible error reducer could be:
# Define t globaly inside create() method
def create(response):
t = None
if response.method == "POST":
现在，您已经在函数内部全局定义了 t = None ，它不会显示以前显示的错误.但是，仍然会有问题，因为 t 为 None .因此，它没有任何属性 id .因此，没有属性DosNotExist .因此，您必须考虑到表单无效时该怎么办，在哪里重定向.
Now, you have defined t=None globally inside function, it will not show the error it was showing before. But, there will still be problem because t is None. So, it won't have any attribute id. Hence, has no attribute DoesNotExist will be shown. Therefore, you have to think that what to do if form is not valid, where to redirect.
或者，如果表单无效，则可以使用else语句处理该问题.喜欢:
Or, you can deal with the problem with else statement if form is not valid. Like:
def create(response):
if response.method == "POST":
form = CreateNewTrade(response.POST)
# Because form.is_valid() failed, t will be undefined
if form.is_valid():
n = form.cleaned_data["name"]
# Here only, you have assigned value of t
t = AssetList(name=n)
t.save()
response.user.assetlist.add(t)
return HttpResponseRedirect("/userdash/%i" %t.id)
# When if statements doesnot apply, always come to this line unless it goes inside form.is_valid()
return HttpResponseRedirect("/userdash/") # redirect to the page whose arguments doesnot depend upon the form subbmission
现在，希望您能理解问题所在.
Now, I hope you understood what was the problem.
这篇关于分配之前引用的django局部变量't'的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
