python - 如何解决 ValueError:在 Django 中解包的值太多(预期为 2)
问题描述
我一直在 Django App 工作。基本上,该应用程序的功能是使用表单将输入作为用户的主题名称,获取该特定用户的该主题的进度活动的详细信息,并将每个详细信息保存在单个变量中。它涉及3个模型,即。User Model(Django 的默认)Subject Model 和 Detail Model,最后它会使用那些分配了 details 的变量,并使用 计算性能fuzz_algo()
,然后将结果以 Messages 的形式返回给 Template。
一切似乎都很好,但是当我单击模板中的计算按钮时,它会在此语句中users/performance_calculator.html
出现此错误ValueError: too many values to unpack (expected 2)
skype = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('skype_session_attendance')
views.py
我的意见.py:
from django.shortcuts import render, redirect
from django.contrib import messages
from .forms import PerformanceCalculatorForm
from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import User
from .models import Subject, Detail
from .fuzzy_logic_algo import fuzz_algo
def performanceCalculator(request):
skype = 0
internal_course = 0
prg_lab = 0
mid_marks = 0
final_marks = 0
sub = 0
if request.method == 'POST':
performance_form = PerformanceCalculatorForm(request.POST)
if performance_form.is_valid():
performance_form.save()
sub = performance_form.cleaned_data.get('subject')
skype = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('skype_session_attendance')
internal_course = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('internal_course_marks')
prg_lab = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('programming_lab_activity')
mid_marks = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('mid_term_marks')
final_marks = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('final_term_marks')
result = fuzz_algo(skype, internal_course, prg_lab, mid_marks, final_marks)
messages.success(request, result)
return redirect('performance_calculator')
else:
performance_form = PerformanceCalculatorForm()
context = {
'performance_form': performance_form
}
return render(request, 'users/performance_calculator.html', context)
我的模型.py:
from django.db import models
from django.contrib.auth.models import User
class Subject(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
subject = models.CharField(max_length=100)
def __str__(self):
return '{} ({})'.format(self.subject, self.user.username)
class Detail(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
subject = models.OneToOneField(Subject, on_delete=models.CASCADE)
skype_session_attendance = models.FloatField()
internal_course_marks = models.FloatField()
programming_lab_activity = models.FloatField()
mid_term_marks = models.FloatField()
final_term_marks = models.FloatField()
def __str__(self):
return f'{self.subject, (self.user.username)} Details'
class Sub(models.Model):
s = models.CharField(max_length=100)
我的forms.py:
from django import forms
from .models import Profile, Sub
class PerformanceCalculatorForm(forms.ModelForm):
subject = forms.CharField(max_length=100)
class Meta:
model = Sub
fields = ['subject']
我的performance_calculator.html(模板):
{% load static %}
{% load crispy_forms_tags %}
<!DOCTYPE html>
<html>
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<link rel="stylesheet" type="text/css" href="{% static 'esacp/main.css' %}">
<title>Expert System for Assessing Programming Course Performance</title>
</head>
<body>
<main role="main" class="container">
<div class="row">
<div class="col-md-8">
{% if messages %}
{% for message in messages %}
<div class="alert alert-{{ message.tags }}">
{{ message }}
</div>
{% endfor %}
{% endif %}
{% if not request.user.is_superuser and not request.useris_staff %}
<div class="account-heading">
<h2>
Performance Calculator
</h2>
</div>
<div class="content-section">
<form method="POST">
{% csrf_token %}
<fieldset class="form-group">
<legend class="border-bottom mb-4"></legend>
{{ performance_form|crispy }}
</fieldset>
<div class="from-group">
<button class="btn btn-outline-info" type="submit">Calculate</button>
</div>
</form>
</div>
{% endif %}
</div>
</div>
</main>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</body>
</html>
我在声明中得到的完整错误skype = Detail.objects.filter(subject__subject=sub, user__username=User.username).get('skype_session_attendance')
是:
ValueError at /esacp/performance-calculator/
too many values to unpack (expected 2)
Request Method: POST
Request URL: http://localhost:8000/esacp/performance-calculator/
Django Version: 3.0.3
Exception Type: ValueError
Exception Value:
too many values to unpack (expected 2)
Exception Location: C:\environments\bsse_fyp\lib\site-packages\django\db\models\sql\query.py in build_filter, line 1247
Python Executable: C:\environments\bsse_fyp\Scripts\python.exe
Python Version: 3.8.1
Python Path:
['C:\\Users\\khubi\\OneDrive\\Desktop\\FYP\\test_phase',
'C:\\Users\\khubi\\AppData\\Local\\Programs\\Python\\Python38-32\\python38.zip',
'C:\\Users\\khubi\\AppData\\Local\\Programs\\Python\\Python38-32\\DLLs',
'C:\\Users\\khubi\\AppData\\Local\\Programs\\Python\\Python38-32\\lib',
'C:\\Users\\khubi\\AppData\\Local\\Programs\\Python\\Python38-32',
'C:\\environments\\bsse_fyp',
'C:\\environments\\bsse_fyp\\lib\\site-packages']
Server time: Thu, 14 May 2020 07:12:19 +0000
我不知道出了什么问题以及为什么显示此错误。我在这里阅读了与相同问题相关的其他线程,但他们的问题是他们使用的是 2D 元组而不是 1D 元组,或者有时是字典或列表问题,但我没有这些问题。
我花了几个小时寻找这个问题,但我找不到一个。帮助将不胜感激。
解决方案
detail = Detail.objects.filter(...).first()
if detail:
skype = detail.skype_session_attendance
您正在调用实例的get
方法。QuerySet
这需要 kwargs 并返回一个实例,如果结果为 None 或有多个实例则抛出错误。要获得 Skype 价值,您必须首先获得实例。
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