【问题标题】：Passing Django forms' result to a page将 Django 表单的结果传递给页面
【发布时间】：2012-10-18 21:49:51
【问题描述】：

我已经为此工作了一段时间，我决定寻求您的帮助。我有一个正在进行的项目，我正在使用 django 框架来构建站点。我有一个请求用户输入的 html 页面，我已经能够使用form.cleaned_data[''] 提取给定的数据。一个

#This is my views.py;



 from django.shortcuts import render_to_response
    from django.template import RequestContext

    from forms import CarloanForm


    def index(request):
        form = CarloanForm()
        if request.POST:
            form = CarloanForm(request.POST)
            if form.is_valid():
                form.save()
        else:
            form = CarloanForm()
        return render_to_response('carloan/index.html', {'form': form},
                      context_instance=RequestContext(request))

#I am extracting the user inputs using;

amount_of_vehicle = form.cleaned_data['cost_of_vehicle_Naira'] 
tenure = form.cleaned_data['loan_repayment_tenure_Months']
interest_rate = form.cleaned_data['interest_rate_Percentage']
equity = form.cleaned_data['equity_contrib_rate_Percentage']
depreciation_rate = form.cleaned_data['depreciation_rate_Percentage']

我需要做但不知道如何去做的事情是；

对数据进行一些操作（使用form.cleaned_data['']提取），我为此编写了几行代码；

class LoanCalc:
    def __init__(self,amount_of_vehicle,tenure,interest_rate,equity,depreciation_rate):
        self.amount_of_vehicle = float(amount_of_vehicle)
        self.tenure = float(tenure)
        self.interest_rate = float(interest_rate)
        self.equity = float(equity)
        self.depreciation_rate = float(depreciation_rate)
    def interest(self):
        return (self.interest_rate/100) * self.amount_of_vehicle *(self.tenure/12)
    def management_fee(self):
        return 0.01 * (self.amount_of_vehicle + user.interest())
    def processing_fee(self):
        return 0.0025 *(self.amount_of_vehicle + user.interest())
    def legal_fee(self):
        return 0.0075 * (self.amount_of_vehicle + user.interest())
    def residual_amount(self):
        return 0.01 * (self.amount_of_vehicle - ((self.depreciation_rate/100) * self.amount_of_vehicle *(self.tenure/12)))
    def equity_contribution(self):
        return (self.equity/100) * self.amount_of_vehicle
    def LoanPaymentPlan(self):
        months = 1
        total_amount = self.amount_of_vehicle+user.interest()+user.management_fee()+user.processing_fee()+user.legal_fee()+user.residual_amount()
        upfront_payment = user.management_fee()+user.processing_fee()+user.legal_fee()+user.equity_contribution()+user.residual_amount()
        opening_balance = total_amount - upfront_payment
        balance = opening_balance
        while months <= self.tenure:
            if balance > 0:
                monthly_instalment =(opening_balance/self.tenure)
                monthly_interest = (((self.interest_rate/100) * balance)/ 12)
                loan_payment = monthly_instalment - monthly_interest
                closing_balance = balance - monthly_instalment
                print'  ',months,'  ',round(balance,2),'   ', round(monthly_instalment,2),'        ',round(monthly_interest,2) \
                , '       ',' ',round(loan_payment,2),'     ',round(closing_balance,2)
                balance = closing_balance
                months += 1
return 'Thank you for using the Loan Calculator App'

我想对提取的数据执行上述代码中的操作。

我正在考虑以这样的方式进行；

创建一个空字典；

    user = {}
    user = LoanCalc(amount_of_vehicle,tenure,interest_rate,equity,depreciation_rate)
    result= user.interest()
    result1 = user.management_fee()
     .           .
     .           .
     .           .
    result10 = user.LoanPaymentPlan()

将从（问题 2）获得的结果传递给生成表单的同一模板。

请帮帮我，我对 django 还是很陌生。谢谢

这是引用错误的完整堆栈：

Environment:


Request Method: GET
Request URL: http://127.0.0.1:9000/result/

Django Version: 1.4.1
Python Version: 2.5.4
Installed Applications:
('django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'carloan')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware')


Traceback:
File "C:\Python25\Lib\site-packages\django\core\handlers\base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "C:\Users\AJIBIKE\Documents\Circuit Atlantic\calculator\carloan\views.py" in result_page
  226.         'carloan': instance,

def result_page(request):
    if request.POST:
        form = Carloan_formForm(request.POST)
        if form.is_valid():
            instance = form.save(commit=False)
            instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle * (instance.tenure/12)
            instance.save()
    else:
        form = Carloan_formForm()
    return render_to_response('carloan/result.html', {'carloan': instance,'form': form},
                  context_instance=RequestContext(request))


Exception Type: UnboundLocalError at /result/
Exception Value: local variable 'instance' referenced before assignment

最新

from django.shortcuts import render_to_response
from django.template import RequestContext
from django.http import HttpResponseRedirect, HttpResponse

from forms import Carloan_formForm


def index(request):
    if request.POST:
        form = Carloan_formForm(request.POST)
        if form.is_valid():
            instance = form.save()
            return HttpResponseRedirect ('/result/')
    form = Carloan_formForm()
    kwvars = {
            'form': form,
            }
    return render_to_response('carloan/index.html', kwvars,
                  context_instance=RequestContext(request))


def result_page(request):
    instance = None
    if request.POST:
        form = Carloan_formForm(request.POST)
        if form.is_valid():
            instance = form.save(commit=False)
            instance.interest = (instance.interest_rate_Percentage/100) * instance.cost_of_vehicle_Naira * (instance.loan_repayment_tenure_Months/12)
            instance.management_fee = 0.01 * (instance.cost_of_vehicle_Naira + instance.interest)
            instance.processing_fee = 0.0025 * (instance.cost_of_vehicle_Naira + instance.interest)
            instance.legal_fee = 0.0075 * (instance.cost_of_vehicle_Naira + instance.interest)
           #i get syntax error starting from this line, and when i comment it out and the lines below, there is no syntax error.
            instance.residual_amount = 0.01 * ((instance.cost_of_vehicle_Naira - ((instance.depreciation_rate_Percentage/100) * instance.cost_of_vehicle_Naira * (instance.tenure/12))) 
            instance.equity_contribution = (instance.equity_contrib_rate_Percentage/100) * instance.cost_of_vehicle_Naira)
            instance.save()
    else:
        form = Carloan_formForm()
    return render_to_response('carloan/result.html', {'instance': instance, 'form': form},
                  context_instance=RequestContext(request))
forms.py

from django import forms
from django.forms import ModelForm

from models import Carloan_form

class Carloan_formForm(ModelForm):
    class Meta:
        model = Carloan_form
        exclude = ('interest', 'management_fee', 'processing_fee', 'legal_fee', \
                   'residual_amount', 'equity_contribution')

【问题讨论】：

标签： html django

【解决方案1】：

1 保存在 Django Administration 中对提取的数据执行的操作的结果。（注意：我已经知道如何保存用户输入）

创建一个模型来保存用户的条目。 app/models.py

class Carloan(models.Model) :
    # In addition to your model fields add the functions that are part of your LoanCalc
    ...

然后创建一个ModelForm：app/forms.py

class CarLoanForm(forms.ModelForm) :
    class Meta:
        model = Carloan

以与通常相同的方式使用 CarLoanForm，除了：app/views.py

if request.POST:
    form = CarloanForm(request.POST)
    if form.is_valid():    
        carloan = form.save()
        #pass carloan (the instance) to the template and 
        #call its functions(from LoanCalc) instead of 
        #passing all of the values separately

最后，注册这个模型，让它出现在管理部分app/admin.py

from django.contrib import admin
from app.models import Carloan

admin.sites.register(Carloan)

2 我将页面分为两部分（一个用于表单，另一个用于结果），我想将结果传递给页面的一半让用户看到它。

使用上述步骤，carloan 将被传递给视图。继续渲染它的值。

另外：

重构索引

您的索引定义应该稍微重构一下，否则您的 POST 绑定表单将永远无法进入模板：

def index(request):
    if request.POST:
        form = CarloanForm(request.POST)
        if form.is_valid():
            instance = form.save()
    else :
        form = CarloanForm()

    return render_to_response('carloan/index.html', {'form': form},
              context_instance=RequestContext(request))

重构您的 ModelForm

对数据进行一些操作（使用 form.cleaned_data[''] 提取），我为此编写了几行代码； - 使用 ModelForm 而不是常规的 django 表单你会得到一个模型的实例已经填写了用户的值，你用instance.field引用它们。

我想对提取的数据执行上述代码中的操作。 - 您计划为其计算值的字段列在排除中，它们将不考虑表单验证。

class CarLoanForm(forms.ModelForm) :
    class Meta:
        model = Carloan
        # exclude fields that are calculated from user input
        # NOTE: these fields must be in your model
        exclude = ('interest', 'management_fee'...)

重构结果页面

对数据进行一些操作（使用 form.cleaned_data[''] 提取），我为此编写了几行代码；

在form.is_valid检查下的results_page中，有一行：instance = form.save(commit=False)这将获取用户在尚未保存的Carloan模型实例中提交的所有值。
进一步向下：instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle *(instance.tenure/12) 在这一行中我正在计算排除字段值之一（此计算是您的代码的副本）。
最后（对数据的所有操作都完成后）我保存模型的实例。
然后将实例传递给模板进行显示。

代码：

def result_page(request):
    if request.POST:
        form = CarloanForm(request.POST)
        if form.is_valid():
            # get an instance from the form but don't save it
            instance = form.save(commit=False)
            # calculate excluded field values
            instance.interest = (instance.interest_rate/100) * instance.amount_of_vehicle *(instance.tenure/12)
            ...
            # after you have calculated all of the excluded fields save the instance
            instance.save()

    else :
        form = CarloanForm()

    return render_to_response('carloan/result.html', {'carloan' : instance, 'form' : form},
                          context_instance=RequestContext(request))

错误：

reference before error assignment - 分配前引用了什么？请粘贴整个堆栈跟踪。

【讨论】：

非常感谢您抽出时间回答我的问题。不幸的是，你还没有真正解决我的问题。我已经知道如何保存用户条目。我想知道的是如何保存用户输入的结果，它必须经过一些操作才能显示给用户。
主要是，我想说明使用 ModelForm 而不是常规 Form。我将添加一些额外的代码来说明计算值。
非常感谢 Francis Yaconiello 先生抽出时间回答我的问题。我想我没有让你足够理解，但我会尽可能地这样做。请重新检查打开的帖子，我已经重新修改了它。期待您的及时回复。
如果我没有很好地理解这个问题，我很抱歉。但是根据您上面的附加信息，我认为我的解决方案将完全适合您。在我的回答中查找您问题中的粗体引号，我已直接回复。
感谢您的光临伸出援助之手。我将尝试按照您的建议进行操作，但我有一个关于“class CarLoanForm(forms.ModelForm) 的问题：class Meta: model = Carloan # 排除根据用户输入计算的字段 # 注意：这些字段必须在您的模型中排除= ('interest', 'management_fee'...)

【解决方案2】：

其中一种更简单的方法是将会话中的数据存储在一个视图中，然后在下一个视图中检索它。 docs 会有所帮助。1

话虽如此 - 还有其他一些方法可以解决这个问题。它已在 SO 上多次讨论过：

【讨论】：

感谢大家的贡献，我已经解决了。不得不使用OOP的概念