Call variables in two different functions

Question

I'm asking How I can call a variable with Python 2.7 and Django 1.10 which is defined in the function1 into the function2.

I defined a function1 like that :

def Test(request) :
  form = TestForm(request.POST or None)
  if form.is_valid() :  
      instance = form.save(commit=False)
      return HttpResponseRedirect('toto')
  context = {
      "form" : form,
      }
  return render(request, 'form_Test.html', context)

And I would like to call the variable instance inside my function2 :

def Test2(request) :
    
    identity = instance.lastname

    context = {
       "identity" : identity,
   }

    return render(request, 'test2_identity.html',context)

I would like to know How it's possible to do this handle ?

----------------------------------------------------------------------------------------------

EDIT :

I tried to handle all things in the same view, with a preview step :

#views.py

def IdentityFormulary(request) :

    form = IdentityForm(request.POST or None)
    template_name = 'form_Identity.html'

    if form.is_valid() :  
        if '_preview' in request.POST :
            post = form.save(commit=False)
            template_name = 'preview.html'
            #if .is_valid() :
                #post=form.save()
        
        elif '_save' in request.POST :
            post = form.save()
            return HttpResponseRedirect('formulaire_traite')

    context = {
        "form" : form,
            }

    return render(request, template_name, context)


def CompletedFormulary(request) :
    
    identity = Identity.objects.all().order_by("-id")[0]

    context = {
       "identity" : identity,
   }

    return render(request, 'recapitulatif_identity.html',context)

The preview.html file :

<!--preview.html-->

<h2 align="center"> Prévisualisation du formulaire </align> </h2>

{% block content %} 

<h3> Récapitulatif des données enregistrées : </h3>

<li> Civilité : {{form.title}}</li>
<li> Nom : {{form.lastname}}</li>
<li> Prénom : {{form.firstname}}</li>
<li> Sexe : {{form.sex}}</li>
<li> Date de Naissance : {{form.birthday}}</li>
<li> Ville de Naissance : {{form.birthcity}}</li>
<li> Pays de Naissance : {{form.birthcountry}}</li>
<li> Nationalité : {{form.nationality}}</li>
<li> Profession : {{form.job}}</li>
<li> Adresse : {{form.adress}}</li>
<li> Ville : {{form.city}}</li>
<li> Code Postal : {{form.zip}}</li>
<li> Pays : {{form.country}}</li>
<li> Email : {{form.mail}}</li>
<li> Téléphone : {{form.phone}}</li>

{% endblock %} 

<br></br>

<input type ="submit" name="_save" value="Valider la fiche individuelle" />

I 'm just blocking with the submit button in my preview.html because for the moment, it doesn't work

Answer 1

Short answer: what your asking for is not possible, period. Even a global variable wouldn't work, since nothing garantees that both requests will be served by the same process (and even then there would be a lot of other unsolvable issues).

FWIW that's actually one of the reasons why we use databases a lot in web development - so we can persist state between requests (where a single-user Desktop app could just keep state in memory for the session).

Now you mention in your comments that

I don't want to search from database because I want to get a data resume (something like cache) before to validate it. In this way, I can control data form before submission

If that's the reason you want to share instance between two views then it's just not the way - you have a form, forms DO have validation (that's actually the main reason for django.forms - validating user-submitted data), and you can hook into the validation process at different point to perform any extra validation. IOW : there's just not reason to try to share a variable between two views to validate a form.

EDIT: ok now we have the X part of the XY problem:

What I would like to get is : user are filling a form in a HTML page. Then, he gets a resume and 2 options : submit (with data saving in MySQL database) or modify data form. The second option lets to get one more time the filled form and he can modify one or several values, then submit to database

And the answer is : you don't need two views to handle the case, you just have to track the current "step" (initial submission / preview / edit / final submission), which is not really rocket science - this is easily done with the request method (a GET is for an empty form, anything else is either asking for a preview, edit or final submission) and the submit buttons names (to find out which of the preview / edit / final submission action should be performed). You can get an unsaved instance (for preview) using form.save(commit=False).

Answer 2

This is How I resolved my problem thanks to @brunodesthuilliers :

My views.py file :

#-*- coding: utf-8 -*-

from django.shortcuts import render, render_to_response
from django.http import HttpResponseRedirect, HttpResponse
from django.template import loader
from .models import Identity, Country
from .forms import IdentityForm


def IdentityAccueil(request) :

    template = loader.get_template('accueil_Identity.html') 
    return HttpResponse(template.render(request))

def IdentityFormulary(request) :

    form = IdentityForm(request.POST or None)
    template_name = 'form_Identity.html'

    if form.is_valid() :  
        if '_preview' in request.POST :
            post = form.save(commit=False)
            template_name = 'preview.html'

        elif '_save' in request.POST :
            post = form.save()
            return HttpResponseRedirect('formulaire_traite')

    context = {
        "form" : form,
            }

    return render(request, template_name, context)


def CompletedFormulary(request) :

    identity = Identity.objects.all().order_by("-id")[0]

    context = {
       "identity" : identity,
   }

    return render(request, 'recapitulatif_identity.html',context)

My preview.html file :

<h2 align="center"> Prévisualisation du formulaire </align> </h2>

<form method='POST' action=''> {% csrf_token %}
{% block content %} 

<h3> Récapitulatif des données enregistrées : </h3>

<li> Civilité : {{form.title}}</li>
<li> Nom : {{form.lastname}}</li>
<li> Prénom : {{form.firstname}}</li>
<li> Sexe : {{form.sex}}</li>
<li> Date de Naissance : {{form.birthday}}</li>
<li> Ville de Naissance : {{form.birthcity}}</li>
<li> Pays de Naissance : {{form.birthcountry}}</li>
<li> Nationalité : {{form.nationality}}</li>
<li> Profession : {{form.job}}</li>
<li> Adresse : {{form.adress}}</li>
<li> Ville : {{form.city}}</li>
<li> Code Postal : {{form.zip}}</li>
<li> Pays : {{form.country}}</li>
<li> Email : {{form.mail}}</li>
<li> Téléphone : {{form.phone}}</li>

{% endblock %} 

<br></br>

<input type ="submit" name="_save" value="Valider la fiche individuelle" />

</form>