Projekt s formulármi

   1 {% extends "base.html" %}
   2 {% block nadpis %}
   3 Formulár
   4 {% endblock %}
   5 {% block obsah %}
   6 <form action="/form/" method="POST">
   7 <table id="border">
   8 {{ form.as_table }}
   9 </table>
  10 <input type="submit" value="Odošli" />
  11 </form>
  12 {% endblock %}

   1 # -*- coding: utf-8 -*-
   2 from django import forms
   3 from django.shortcuts import render_to_response
   4 
   5 class MathOpForm(forms.Form):
   6     operand1=forms.IntegerField(required=True)
   7     operand2=forms.IntegerField(required=True)
   8     operation=forms.ChoiceField(choices=[('+','+'),('-','-'),('*','*')],required=True)
   9 
  10 
  11 __oper_map={'+':'__add__','-':'__sub__','*':'__mul__'}
  12 
  13 def math_form(request):
  14 
  15     global __oper_map
  16 
  17     if request.method=='POST':
  18         form=MathOpForm(request.POST)
  19         # form.is_valid() skontroluje,
  20         # ci su udaje vo formulari v poriadku
  21         if form.is_valid():
  22             # Vzhladom na to, ze form.is_valid() je True,
  23             # mozeme tu uz predpokladat, ze data su v poriadku.
  24             
  25             # slovnik cleaned_data uz obsahuje *cisla* ako operandy
  26             operand1=form.cleaned_data['operand1']
  27             operand2=form.cleaned_data['operand2']
  28             # operation je retazec
  29             operation=form.cleaned_data['operation']
  30 
  31             # Trochu pythonovskeho voodoo:
  32             # * operation je jedna z '+','-','*'
  33             # * __oper_map je globalna premenna tohto modulu typu slovnik (vid hore)
  34             # * __oper_map['+'] je napr. retazec '__add__'
  35             # * operand1 je typu int
  36             # * getattr(operand1,'__add__') vrati viazanu metodu z namespace
  37             #   toho objektu typu int
  38             # * tejto metode je poslany operand2_int
  39             #
  40             # Skuste si na pythonovskom prompte:
  41             # 1.__add__
  42             # 1.__add__(2)
  43             # getattr(1,'__add__')
  44             # getattr(1,'__add__')(2)
  45             if not (operation in __oper_map):
  46                 # Sem sa nikdy nedostaneme, to zabezpeci .is_valid
  47                 # Ale istota je istota
  48                 return(render_to_response("chyba.html",
  49                     {'chyba':u"Neznáma operácia"}))
  50             vysledok=getattr(operand1,__oper_map[operation])(operand2)
  51             return(render_to_response("vysledok.html",
  52                 {'operand1':operand1,
  53                  'operand2':operand2,
  54                  'operation':operation,
  55                  'vysledok':vysledok}))
  56     else: 
  57         form=MathOpForm()
  58     # Sem sa dostaneme v dvoch pripadoch
  59     # 1) request.method nie je 'POST', teda je to takmer iste 'GET'
  60     #    v tom pripade sa vykonalo form=MathOpForm(), a teda formular
  61     #    je prazdny.
  62     # 2) form.is_valid() vratilo False, v tom pripade je form zkonstruovany
  63     #    z POST requestu s vyznacenymi chybami.
  64     return(render_to_response("form.html",{'form':form}))