validation - django validationerror not being raised -

so have created a dynamic formset allows user add or remove many forms want. now, trying custom validation in field(block_name) in forms.

it seems working because if user input doesn't match regex, data not saved. problem there no message showing input wrong.

also, if user inputs incorrect data , tries submit page redirect , erase input data. how can make page stay in same view if input wrong , show error messages?

forms.py:

import re django import forms django.forms.models import modelformset_factory inventory.models import block django.core.exceptions import validationerror django.core.validators import regexvalidator   # form block requests class blockform(forms.modelform): block_name = forms.charfield(required=true, validators= [regexvalidator('^s\d{3}rf\d*b\d*e\d+r\d+w\d*[cgls][abcdex][ed][hv][sbaec][a-d] [a-d][0-7][apfg]a', message="please enter valid block name",  code="invalid_name")])  def __init__(self, *args, **kwargs):     super(blockform, self).__init__(*args, **kwargs)     self.empty_permitted = false  class meta:     model = block     fields = ['block_name', 'block_derivatives', 'block_subsystems', 'owners']  def clean_block_name(self):     print self.cleaned_data     block_name = self.cleaned_data.get('block_name')     if block_name == "a":         print ("block name a")         raise forms.validationerror(             ('please enter block name'))                  return block_name 

models.py:

import datetime import re django.core.validators import regexvalidator django.core.exceptions import validationerror  django.db import models  django.utils import timezone  class inventory(models.model):     class meta:         verbose_name_plural = "inventories"  inventory_name = models.charfield(max_length=100) pub_date = models.datetimefield('date published')  def __str__(self):              # __unicode__ on python 2     return self.inventory_name  def was_published_recently(self):     return self.pub_date >= timezone.now() - datetime.timedelta(days=1)  class block(models.model):     class meta:         verbose_name_plural = "request blocks"  inventory = models.foreignkey(inventory, null=true) block_status = models.charfield(max_length=20, blank=false) #617block_name = models.charfield(max_length=50, blank=false, null=false, validators=[block_nametest]) block_name = models.charfield(max_length=50, blank=false, null=false) block_derivatives = models.charfield(max_length=100) block_subsystems = models.charfield(max_length=40) owners = models.charfield(max_length=100)   def __str__(self):                   return self.block_name  def block_owners(self):     return str(self.owners) 

views.py:

from django.forms.models import modelformset_factory django.forms.formsets import formset_factory django.shortcuts import render, get_object_or_404 django.http import httpresponseredirect django.core.urlresolvers import reverse django.views import generic django.http import httpresponse django.shortcuts import render_to_response    .models import inventory, block .forms import blockform # create views here.   def requests(request, inventory_id):     blockformset = formset_factory(blockform, extra=1)     inventory = get_object_or_404(inventory, pk=inventory_id)     formset = blockformset(request.post)     if request.method == 'post':         formset = blockformset(request.post)         if formset.is_valid():             form in formset:                            print form             form.save()             print "success"             return httpresponseredirect('/inventory/2')         else:             print "yo, stuff not validated"      else:               print "lolololol"      return render(request, 'inventory/requests.html', {'inventory': inventory, 'formset': blockformset}) 

requests.html:

{% block content %} <div class="requestform"> <form id="blockform" class="original" action="{% url 'inventory:requests' inventory.id %}" method="post">{% csrf_token %}    <!-- <a href="#" id="insert-more"> add new row </a> -->            {{formset.management_form}}          {% form in formset %}          <div class='item'>             <ul>{{ form.as_table}}<ul>             <p style=""><a class="delete" href="#">delete</a></p>         </div>         {% endfor %}          <p><a id="add" href="#">add item</a></p>          <input type="submit" name="submit" value="request blocks" id="submitbutton">     </form> </div> {% endblock %} 

you're redirecting after invalid post, rather redisplaying same form. though redirect same view, loses post data , form therefore blank.

drop first else block, , let execution fall through final render line.