当我尝试查看网页源代码时出现Django错误

时间：2015-02-04 03:43:49

标签： python html django post hidden-field

我正在使用Django为一个类创建一个Web应用程序。下面的HTML片段是我认为可能导致我的问题。

<form action="press" method="POST">
<table>
  <tr>
      <td colspan="4">
      {% if output %}
        <input id="output" name="output" type="text" value="{{output}}" readonly>
      {% else %}
        <input id="output_hidden" name="output" type="text" value="0" readonly>
      {% endif %}
      <input type="hidden" name="buttVal" value="{{buttVal}}">
      <input type="hidden" name="currVal" value="{{currVal}}">
      <input type="hidden" name="prevVal" value="{{prevVal}}">
      <input type="hidden" name="math" value="{{math}}">
      {% csrf_token %}
      </td>

我使用隐藏字段来存储值以保持会话无状态（分配点）。我尝试调试隐藏字段，但是，在我启动应用并触发下面的第一个if语句后，我再也无法查看网页来源（通过右键点击网页并点击＆＃34;查看来源＆＃34;）。当我尝试这个时，它首先说＆＃34;文件已过期＆＃34;但它允许我再次尝试请求。当我再次尝试时，下面的html显示为源。

    <!DOCTYPE html>
<html lang="en">
<head>
  <meta http-equiv="content-type" content="text/html; charset=utf-8">
  <meta name="robots" content="NONE,NOARCHIVE">
  <title>MultiValueDictKeyError at /press</title>
  <style type="text/css">
    html * { padding:0; margin:0; }
    body * { padding:10px 20px; }
    body * * { padding:0; }
    body { font:small sans-serif; }
    body>div { border-bottom:1px solid #ddd; }
    h1 { font-weight:normal; }
    h2 { margin-bottom:.8em; }
    h2 span { font-size:80%; color:#666; font-weight:normal; }
    h3 { margin:1em 0 .5em 0; }
    h4 { margin:0 0 .5em 0; font-weight: normal; }
    code, pre { font-size: 100%; white-space: pre-wrap; }
    table { border:1px solid #ccc; border-collapse: collapse; width:100%; background:white; }
    tbody td, tbody th { vertical-align:top; padding:2px 3px; }
    thead th { padding:1px 6px 1px 3px; background:#fefefe; text-align:left; font-weight:normal; font-size:11px; border:1px solid #ddd; }
    tbody th { width:12em; text-align:right; color:#666; padding-right:.5em; }
    table.vars { margin:5px 0 2px 40px; }
    table.vars td, table.req td { font-family:monospace; }
    table td.code { width:100%; }
    table td.code pre { overflow:hidden; }
    table.source th { color:#666; }
    table.source td { font-family:monospace; white-space:pre; border-bottom:1px solid #eee; }
    ul.traceback { list-style-type:none; color: #222; }
    ul.traceback li.frame { padding-bottom:1em; color:#666; }
    ul.traceback li.user { background-color:#e0e0e0; color:#000 }
    div.context { padding:10px 0; overflow:hidden; }
    div.context ol { padding-left:30px; margin:0 10px; list-style-position: inside; }
    div.context ol li { font-family:monospace; white-space:pre; color:#777; cursor:pointer; }
    div.context ol li pre { display:inline; }
    div.context ol.context-line li { color:#505050; background-color:#dfdfdf; }
    div.context ol.context-line li span { position:absolute; right:32px; }
    .user div.context ol.context-line li { background-color:#bbb; color:#000; }
    .user div.context ol li { color:#666; }
    div.commands { margin-left: 40px; }
    div.commands a { color:#555; text-decoration:none; }
    .user div.commands a { color: black; }
    #summary { background: #ffc; }
    #summary h2 { font-weight: normal; color: #666; }
    #explanation { background:#eee; }
    #template, #template-not-exist { background:#f6f6f6; }
    #template-not-exist ul { margin: 0 0 0 20px; }
    #unicode-hint { background:#eee; }
    #traceback { background:#eee; }
    #requestinfo { background:#f6f6f6; padding-left:120px; }
    #summary table { border:none; background:transparent; }
    #requestinfo h2, #requestinfo h3 { position:relative; margin-left:-100px; }
    #requestinfo h3 { margin-bottom:-1em; }
    .error { background: #ffc; }
    .specific { color:#cc3300; font-weight:bold; }
    h2 span.commands { font-size:.7em;}
    span.commands a:link {color:#5E5694;}
    pre.exception_value { font-family: sans-serif; color: #666; font-size: 1.5em; margin: 10px 0 10px 0; }
  </style>

  <script type="text/javascript">
  //<!--
    function getElementsByClassName(oElm, strTagName, strClassName){
        // Written by Jonathan Snook, http://www.snook.ca/jon; Add-ons by Robert Nyman, http://www.robertnyman.com
        var arrElements = (strTagName == "*" && document.all)? document.all :
        oElm.getElementsByTagName(strTagName);
        var arrReturnElements = new Array();
        strClassName = strClassName.replace(/\-/g, "\-");
        var oRegExp = new RegExp("(^|\s)" + strClassName + "(\s|$)");
        var oElement;
        for(var i=0; i<arrElements.length; i++){
            oElement = arrElements[i];
            if(oRegExp.test(oElement.className)){
                arrReturnElements.push(oElement);
            }
        }
        return (arrReturnElements)
    }
    function hideAll(elems) {
      for (var e = 0; e < elems.length; e++) {
        elems[e].style.display = 'none';
      }
    }
    window.onload = function() {
      hideAll(getElementsByClassName(document, 'table', 'vars'));
      hideAll(getElementsByClassName(document, 'ol', 'pre-context'));
      hideAll(getElementsByClassName(document, 'ol', 'post-context'));
      hideAll(getElementsByClassName(document, 'div', 'pastebin'));
    }
    function toggle() {
      for (var i = 0; i < arguments.length; i++) {
        var e = document.getElementById(arguments[i]);
        if (e) {
          e.style.display = e.style.display == 'none' ? 'block': 'none';
        }
      }
      return false;
    }
    function varToggle(link, id) {
      toggle('v' + id);
      var s = link.getElementsByTagName('span')[0];
      var uarr = String.fromCharCode(0x25b6);
      var darr = String.fromCharCode(0x25bc);
      s.innerHTML = s.innerHTML == uarr ? darr : uarr;
      return false;
    }
function switchPastebinFriendly(link) {
  s1 = "Switch to copy-and-paste view";
  s2 = "Switch back to interactive view";
  link.innerHTML = link.innerHTML == s1 ? s2: s1;
  toggle('browserTraceback', 'pastebinTraceback');
  return false;
}
//-->

除此之外，我不确定发生了什么。我试过谷歌搜索问题，但我对这种情况缺乏了解使我无法找到任何有用的东西。希望有人可以指出我做得不好的事情。

- 编辑 - 这是我的views.py文件。

from django.shortcuts import render
from django.http import HttpResponse


# Create your views here.
def home_page(request):
    index = 'calculator/calculator.html'
    return render(request,index,{})

def press(request):
    context = {}
    operators = ['plus','minus','divide','multiply']
    index = 'calculator/calculator.html'

    ## Discerns from a number and an operator press
    if 'val' in request.POST and is_int(request.POST['val']):
        if request.POST['output'] == '0':
            context['output'] = request.POST['val']
            context['buttVal'] = request.POST['val']
            context['currVal'] = request.POST['val']
        elif request.POST['currVal'] == '0':
            context['output'] = request.POST['val']
            context['buttVal'] = request.POST['val']
            context['currVal'] = request.POST['val']
        else:
            newOutput = request.POST['output'] + request.POST['val']
            context['buttVal'] = request.POST['val']
            context['currVal'] = newOutput
            context['output'] = newOutput

        context['math'] = request.POST['math']
        context['prevVal'] = request.POST['prevVal']

    elif request.POST['val'] == 'clear':
        context['output'] = 0
        context['buttVal'] = 0
        context['currVal'] = 0
        context['prevVal'] = 0
        context['math'] = ''
    elif request.POST['val'] in operators:
        print request.POST
        if request.POST['math'] != '':
            print "poop"
            if request.POST['math'] == 'plus':
                result = int(request.POST['currVal']) + int(request.POST['prevVal'])
                context['prevVal'] = result
                context['output'] = result
            if request.POST['math'] == 'minus':
                result = int(request.POST['currVal']) - int(request.POST['prevVal'])
                context['prevVal'] = result
                context['output'] = result
            if request.POST['math'] == 'multiply':
                result = int(request.POST['currVal']) * int(request.POST['prevVal'])
                context['prevVal'] = result
                context['output'] = result
            if request.POST['math'] == 'divide':
                result = int(request.POST['currVal']) / int(request.POST['prevVal'])
                context['prevVal'] = result
                context['output'] = result
            if request.POST['val'] == 'equal':
                pass
        else:
            context['prevVal'] = request.POST['currVal']
            #context['math'] = request.POST['val']
            context['output'] = request.POST['output']
        context['math'] = request.POST['val']
        context['buttVal'] = request.POST['buttVal']
        context['currVal'] = 0
    else:
        context['output'] = request.POST['output']
        context['buttVal'] = request.POST['buttVal']
        context['math'] = request.POST['math']
        context['prevVal'] = request.POST['prevVal']

     ## Submits POST
    return render(request, index, context)

## Helper functions
def is_int(string):
    try: 
        int(string)
        return True
    except ValueError:
        return False

2 个答案:

答案 0 :(得分：0)

您正在尝试访问request.POST中不存在的参数。例如：

elif request.POST['val'] == 'clear':
    ...
elif request.POST['val'] in operators:
    ...
else:
    context['output'] = request.POST['output']
    context['buttVal'] = request.POST['buttVal']
    context['math'] = request.POST['math']
    context['prevVal'] = request.POST['prevVal']

您没有检查val，output，buttVal，prevVal和math是否在request.POST。< / p>

要安全地从request.POST获取值，请使用get()方法：

request.POST.get('val')

如果此参数不存在，此表达式将返回val或request.POST的{​​{1}}参数。

添加None和print request.POST视图的最开头，以查看＆＃34;查看来源＆＃34;中的POST数据的内容。请求。

答案 1 :(得分：0)

这种情况会发生，因为当您在浏览器中查看页面源时，会发出另一个请求;但它是一个GET请求。

因此，您的POST字典没有这些键，导致异常。

解决此问题的最简单方法是使用表单。

class MyForm(forms.Form):
    output = forms.TextField()
    # .. your other fields here

def press(request):
    form = MyForm(request.POST or None)
    if form.is_valid():
        # do stuff
        return redirect('/home')
    return render(request, 'template.html', {'form': form})

您可以在documentation了解有关表单的更多信息（包括如何隐藏字段和传递初始值）。

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