Re: Help with Custom model field and Custom validation for EmailField().

[Chris Pagnutti]

Hi.  I'm pretty new to Django too, so someone else probably has a better idea.  But I think that on the server side, you can handle additional validation in the view that handles the form submission (i.e. the view that the "action" attribute in your form points to).  You can probably attach errors to the form in the view too, so if the form data is invalid you can display the errors back to the client.

On Friday, November 2, 2012 4:36:20 AM UTC-4, Dilip M wrote:

Hi,

I am new to Django. Went through docs before posting this.. I have a model and form like this.

models.py:

class Recipients(models.Model):
     dev = models.EmailField()
     qa = models.EmailField()
     cc = models.MultipleEmailField()

forms.py:

class RecipientsForm(forms.ModelForm):

    class Meta:
        model = Recipients


Now I want to,

1. Add *additional* validation for models.EmailField(). Something like check if email id entered exists in LDAP db.
2. Create new model custom field MultipleEmailField(), which would split emails separated by comma and uses modified validation of models.EmailField() done in step 1.

I am going through docs, but not able to figure out how to put things together! Here is what I understood.

MultipleEmailField() should go in <project-name>/fields.py. But how to make it to run default validation of models.EmailField() and than do custom validation?

Any help appreciated..

Thanks. Dilip

[Dilip M]

On Fri, Nov 2, 2012 at 5:52 PM, Chris Pagnutti <chris.p...@gmail.com> wrote:
> Hi. I'm pretty new to Django too, so someone else probably has a better
> idea. But I think that on the server side, you can handle additional
> validation in the view that handles the form submission (i.e. the view that
> the "action" attribute in your form points to). You can probably attach
> errors to the form in the view too, so if the form data is invalid you can
> display the errors back to the client.

Yeah! I think that is one of the way. :) But I guess it can done at
some level at Model validation..

The doc says https://docs.djangoproject.com/en/1.4/topics/forms/modelforms/#overriding-the-clean-method
"if you would like to override the clean() method and maintain the
_default validation_, you must call the parent class's clean()
method."

A example would really help...

:)

[Chris Pagnutti]

Again, I'm not sure, but I think to do it at Model validation level you'd have to modify some of the django core files themselve.  I think what you're looking for is in django.core.validators (in my install this file is at /lib/python2.7/site-packages/django/core/validators.py, or you can just search for validators.py on your system)  But I've had my own troubles that I thought I could solve by modifying the django files themselves (and it works), but everyone that helped me advised that this is not the best way to do it, because future updates of django itself will break your changes.

I think the best way to do it is in your view that handles the form.  For point 2., just make you MultipleEmailField() a CharField instead, and validate it in your view.  For example, you could do something like this (note that I'm pulling lots of this from the docs and here http://stackoverflow.com/questions/3217682/checking-validity-of-email-in-django-python, and I haven't tested it)

from django.shortcuts import render

from django.http import HttpResponseRedirect

def your_form_handling_view(request):

    if request.method == 'POST': # If the form has been submitted...

        form = YourForm(request.POST) # A form that you created in your forms.py

        if form.is_valid(): # All validation rules pass

            # Process the data in form.cleaned_data...get all the fields that require further validation

            your_multipleemail_field = form.cleaned_data['your_multipleemail_field']

            #.... perform the extra validation here, for example

            extra_validation_passes = True

            for email in your_multipleemail_field.split(','):

                if email_id_exists(email) and not(validateEmail(email)):  #assuming some_field is the email id and email_id_exists() is your function that validates it

                    #Create your custom errors here

                    form.your_multipleemail_field.errors = "Email id already exists in LDAP or is invalid"

                    extra_validation_passes = False

            if extra_validation_passes:

                return HttpResponseRedirect('/thanks/') # Redirect after POST

            return render(request, 'template_with_your_form_on_it.html', {'form': form,}) #Now this form goes back to the template with your custom errors.

    else:

        form = YourForm() # An unbound form

    return render(request, 'template_with_your_form_on_it.html', {'form': form,})

This is a separate global function you might want to put somewhere other than views.py (maybe models.py, but don't forget to import it in views.py if you do this)

def validateEmail( email ):
    from django.core.validators import validate_email
    from django.core.exceptions import ValidationError
    try:
        validate_email( email )
        return True
    except ValidationError:
        return False

Again, not sure if this works, I've never added custom errors to a form like this, but I think forms are normal objects and if the .errors are just strings, I don't see why it wouldn't work. In fact it probably doesn't work but it might give you some ideas.  Of course, you could split the conditional "if email_id_exists(email) and not(validateEmail(email)):" to test them separately to give more precise error messages.

Hope that helps.

On Friday, November 2, 2012 4:36:20 AM UTC-4, Dilip M wrote:

Hi,

I am new to Django. Went through docs before posting this.. I have a model and form like this.

models.py:

class Recipients(models.Model):
     dev = models.EmailField()
     qa = models.EmailField()
     cc = models.MultipleEmailField()

forms.py:

class RecipientsForm(forms.ModelForm):

    class Meta:
        model = Recipients


Now I want to,

1. Add *additional* validation for models.EmailField(). Something like check if email id entered exists in LDAP db.
2. Create new model custom field MultipleEmailField(), which would split emails separated by comma and uses modified validation of models.EmailField() done in step 1.

I am going through docs, but not able to figure out how to put things together! Here is what I understood.

MultipleEmailField() should go in <project-name>/fields.py. But how to make it to run default validation of models.EmailField() and than do custom validation?

Any help appreciated..

Thanks. Dilip

[Chris Pagnutti]

Ahh.  Just saw your link to overriding the clean() method.  So you could put all the same logic above into the clean() method instead.

[Dilip M]

Hi Chris,

Thank you very much for your time on this. I am not able to make out on how could I put this under clean() method. Ex: What does "you must call the parent class's clean()" mean in "if you would like to override the clean() method and maintain the _default validation_, you must call the parent class's clean() method."

This clean() method will go in models.py? or forms.py? Any simple examples would be of great help!

Many thanks...Dilip

[Chris Pagnutti]

I've never done it myself, but I think you'd just define the clean method in your Form's class (i.e. in forms.py), and the first line in your clean() method should call the parent classes, clean() method - to do this you need to call the super() method, which is just regular python.  It think the call would look something like this

super(YourFormClass,self).clean()

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[Dilip M]

Hi Abraham,

This is beautiful & is of huge help! thank you. :)

I created a new file named <project-name>/validators.py and add the below code.

from django.core.validators import EmailValidator

from django.core.exceptions import ValidationError

def multi_email_validator(value):
    if value and "," in value:
        for v in value.split(","): # split() returns char list!

            nv = v.strip()  

            try:

                EmailValidator().__call__(nv)

                # email_in_ldap(email)

            except: 

                raise ValidationError("%s is not a valid email" % nv)
    else:
         try:
             EmailValidator().__call__(value)

             # email_in_ldap(email)
          except: 

              raise ValidationError("%s is not a valid email" % value)



def email_in_ldap(email):

    """ Check if email record exists in ldap

    """

 

.

.

.

.

I am using subprocess in email_in_ldap method and hitting Python bug: http://bugs.python.org/issue14308

will upgrade to to fixed revision and try!

thanks to Chris too for alternate solutions...

:)

On Sun, Nov 4, 2012 at 11:46 AM, <bb...@yahoo.com> wrote:

Hi,
If all u nid is a field whose value is a comma separated list of emails den u dont nid a custom field at all. All u nid is a gud ol CharField. Just set it like so:
emails=models.CharField(max_length=500, validators=[multi_email_validator,]).

 

here is what multi_email_validator looks like:
from django.core.validators import EmailValidator
from django.core.exceptions import ValidationError
def multi_email_validator(value):
if value and "," in value:
for v in value.split(",").strip():
try:
EmailValidator().__call__(v)
except: raise ValidationError("%s is not a valid email" % v)
else:
try:
EmailValidator().__call__(value)
except: raise ValidationError("%s is not a valid email" % value)

 

with dis aproach and using modelforms u dont nid to validate in forms or views cos calling form.is_valid with call model field validators too. Hope dis helps.
abraham.

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