As the built in validator in django accepts even if just spaces are input into a field. I want a validation in which if only spaces are fed then it must raise a validation error. I have a field like this:
name = forms.CharField(max_length=200)
Using validators outside i.e. writing a function like this works.
def validate_spaces(value):
if value.strip() == '':
raise ValidationError(u"You must provide more than just whitespace.")
But, I was thinking if it could be done using the form.clean() methods, i.e. without writing any extra functions outside. Any help will be much appreciated.
You can add custom behaviour to form.clean() this way:
class YourForm(forms.Form):
# Everything as before.
...
def clean_name(self):
data = self.cleaned_data['name']
if data.strip() == '':
raise forms.ValidationError(u"You must provide more than just whitespace.")
# Always return the cleaned data, whether you have changed it or
# not.
return data
However, if you want to create a type of field that automatically gets this type of validation, you add a new class like this
class NoSpacesCharField(forms.CharField):
def validate(self, value):
# Use the parent's handling of required fields, etc.
super(NoSpacesCharField, self).validate(value)
if value.strip() == '':
raise ValidationError(u"You must provide more than just whitespace.")
Then uses NoSpacesCharField like you would ordinarily use forms.CharField.
I'm not currently in a position to test this code so there might be the odd kink in it, but it should get you most of the way there. For further info on form validation in Django see https://docs.djangoproject.com/en/dev/ref/forms/validation/
Related
The Optional validator allows for both empty values and if the value is not present (from the docs):
class wtforms.validators.Optional(strip_whitespace=True)
Allows empty input and stops the validation chain from continuing.
If input is empty, also removes prior errors (such as processing
errors) from the field.
I have some additional validators on a field, and I would like if those validators ran even if the input is an empty string. The builtin Optional validator makes the rest of the validators skipped if the input was an empty string. Is there a built in or any other way to achieve this?
Edit: More specifics about my usecase
I am using this form to validate PUT requests. Let's say I have User entities with usernames as ID and middlenames as an optional field. Then the validator for the fields would look something like:
class UserUpdateForm(Form):
username = fields.StringField('username', [
validators.Optional(),
validators.Length(min=5, max=500)
])
middlename = fields.StringField('middlename', [
validators.Optional()
])
So I would allow for PUT requests that does not have a username or middlename parameter, and those would leave the fields untouched. However, when the parameter is present and is an empty string, I would like the username field validation fail because of the Length validator, but I would allow the middlename field to be set to the empty string.
From another perspective: I would like to distinguish non-present parameters and empty string parameters.
I took a look at the source of the Optional validator:
class Optional(object):
...
def __call__(self, form, field):
if not field.raw_data or isinstance(field.raw_data[0], string_types) and not self.string_check(field.raw_data[0]):
field.errors[:] = []
raise StopValidation()
As you can see in and not self.string_check(field.raw_data[0]), empty strings are explicitly considered here. I wonder what would happen if I sent two values like a=foo&a=&b=bar.
Anyway, the quick solution for me was to implement a new validator:
class OptionalButNotEmpty(object):
"""
Allows missing but not empty input and stops the validation chain from continuing.
"""
# Code is a modified version of `Optional` (https://github.com/wtforms/wtforms/blob/master/wtforms/validators.py#L148)
field_flags = ('optional', )
def __call__(self, form, field):
if not field.raw_data:
raise wtforms.validators.StopValidation()
From Marshmallow#validation, I know I can register validators on specific fields in a Schema. If a validator fails, errors in :
data, errors = MySchema().load({"some":"data})
will include error information for any field which has failed validators :
errors
# => some error message for the field that failed
My question : Is it possible to validate at the Schema level (rather than at individual field level) and still return an error in the above way?
As an arbitrary example, say I wanted to validate that you tried to MySchema().load() n distinct keys.
I currently have a #pre_load method which checks the structure of the input and raise ValidationError('message') if the data is ill-formed, but I would like to return it as result.errors like field validation does. What are my options?
You can use validates_schema decorator to run validations on whole object:
class MySchema(marshmallow.Schema):
# ...
#marshmallow.validates_schema(skip_on_field_errors=True)
def validate_object(self, data):
if data['foo'] < data['bar']:
raise marshmallow.ValidationError(
'Value should not be less than bar',
['foo'] # name of field to report error for
)
Although if you want to report multiple errors for different fields independently, Marshmallow at this moment does not support reporting multiple different errors for different fields, and you need to put separate validations into separate methods:
class MySchema(Schema):
# ...
#validates_schema
def validate_foo(self, data):
pass
#validates_schema(skip_on_field_errors=True)
def validate_bar(self, data):
pass
I have subclassed a text-field form field in Django to create my own custom widget for a field. I was wondering if it's possible to check if all other fields of the form are valid (I want its server side behavior to vary based on the validation of other fields)
See comment
Something like:
class CustomField(TextInput):
def __init__(self, *args, **kwargs):
...
super(CustomField, self).__init__(*args, **kwargs)
input_type = 'hidden'
def value_from_datadict(self, data, files, name):
aws_file_key = data.get(name, None)
_media_bucket = boto.connect_s3(settings.AWS_ACCESS_KEY_ID,
settings.AWS_SECRET_ACCESS_KEY)\
.lookup(settings.AWS_MEDIA_STORAGE_BUCKET_NAME)
try:
key = _media_bucket.get_key(aws_file_key)
except:
print 'Failed to get key.'
key = None
if key and aws_file_key:
fh = tempfile.TemporaryFile()
key.get_contents_to_file(fh)
fh.seek(0)
files = SimpleUploadedFile(key.name, fh.read())
### IF FORM IS VALID DELETE KEY, OTHERWISE, KEEP IT.
if code_to_check_if_valid:
_media_bucket.delete_key(key)
fh.close()
return files
...... etc.
If you want to validate a certain field depending on the values of other fields, you need to to it at the form level and overwrite the field's clean method. Here's the docs on the subject - they are very good.
class CustomForm(forms.Form):
custom_field = CustomField()
def clean(self):
cleaned_data = super(CustomForm, self).clean()
custom_field = cleaned_data.get("custom_field")
...
If you look at the flow of how forms are validated, you will see that the clean method is run if all the other fields validate independently, so at this stage, the form can be considered valid:
These methods are run in the order given above, one field at a time. That is, for each field in the form (in the order they are declared in the form definition), the Field.clean() method (or its override) is run, then clean_<fieldname>(). Finally, once those two methods are run for every field, the Form.clean() method, or its override, is executed.
The final clean method is actually run regardless of if there's an error so you have to iterate through the cleaned_data to make sure there are no errors
The clean() method for the Form class or subclass is always run. If that method raises a ValidationError, cleaned_data will be an empty dictionary.
The previous paragraph means that if you are overriding Form.clean(), you should iterate through self.cleaned_data.items(), possibly considering the _errors dictionary attribute on the form as well. In this way, you will already know which fields have passed their individual validation requirements.
The clean methods for individual fields are called in the same order as the form declaration order or explicitly specified order. [django source code]
Although I wouldn't recommend this approach over using the clean method for multi-field validation, if your custom field is the last field in the order, you can expect self._errors to indicate whether all other fields have passed validation or not. However at this stage, non-field errors won't be available.
In Django/Python, when you make a custom form, does it need to have a clean() method, or will calling .is_valid() perform a default validation?
if request.method == 'POST':
filter = FilterForm(request.POST)
if filter.is_valid():
print 'Month is ' + filter.cleaned_data['month']
print 'Type is ' + filter.cleaned_data['type']
print 'Number is ' +filter.cleaned_data['number']
else:
print 'Invalid form'
print filter.errors
"Invalid Form" gets printed but no errors get printed.
class FilterForm(forms.Form):
months = [('January','January'),
('February','February'),
('March','March'),
('April','April'),
('May','May'),
('June','June'),
('July','July'),
('August','August'),
('September','September'),
('October','October'),
('November','November'),
('December','December'),]
types = [('text','Text'),
('call','Call'),]
month = forms.ChoiceField(months)
type = forms.ChoiceField(choices=types,widget=forms.CheckboxSelectMultiple)
def __init__(self,numbers,*args, **kwargs):
super(FilterForm,self).__init__(*args, **kwargs)
self.fields['number'] = forms.ChoiceField(choices=numbers)
def clean(self):
return self.cleaned_data
I've tried it with and without the clean method.
does it need to have a clean() method
No. Completely optional.
There's a big list of things that Django does in a specific order when it validates forms. You can learn about the process here:
http://docs.djangoproject.com/en/dev/ref/forms/validation/
As for finding your problem, if you stick a {{form.errors}} on your template, you'll see which field is blowing up. I have a feeling it could be that your choices is defined in a place that something can't get a handle on when it needs to (Move them out of the class).
Edit: Almost missed this. Look at this line:
def __init__(self,numbers,*args, **kwargs)
And then look at this line:
filter = FilterForm(request.POST)
You need to pass the numbers argument in this time too. It's a completely new instance. it can't validate because it doesn't know what numbers is.
If you have no specific clean method, Django will still validate all the fields in your form to ensure that all required fields are present, that they have the correct type where necessary, and that fields with choices have a value corresponding to one of the choices.
There are a couple of issues with this form that could be causing your problem. Firstly, you have overridden __init__ so that the first parameter after self is numbers. However, when you instantiate the form you don't pass this parameter - you just pass request.POST.
Secondly, it's a bad idea to add fields dynamically to self.fields as you do in __init__. Instead, declare your number field with an empty choices list and just set that in __init__:
self.fields['number'].choices = numbers
Thanks to Insin for answering a previous question related to this one.
His answer worked and works well, however, I'm perplexed at the provision of 'cleaned_data', or more precisely, how to use it?
class RegistrationFormPreview(FormPreview):
preview_template = 'workshops/workshop_register_preview.html'
form_template = 'workshops/workshop_register_form.html'
def done(self, request, cleaned_data):
# Do something with the cleaned_data, then redirect
# to a "success" page.
registration = Registration(cleaned_data)
registration.user = request.user
registration.save()
# an attempt to work with cleaned_data throws the error: TypeError
# int() argument must be a string or a number, not 'dict'
# obviously the fk are python objects(?) and not fk_id
# but how to proceed here in an easy way?
# the following works fine, however, it seems to be double handling the POST data
# which had already been processed in the django.formtools.preview.post_post
# method, and passed through to this 'done' method, which is designed to
# be overidden.
'''
form = self.form(request.POST) # instansiate the form with POST data
registration = form.save(commit=False) # save before adding the user
registration.user = request.user # add the user
registration.save() # and save.
'''
return HttpResponseRedirect('/register/success')
For quick reference, here's the contents of the post_post method:
def post_post(self, request):
"Validates the POST data. If valid, calls done(). Else, redisplays form."
f = self.form(request.POST, auto_id=AUTO_ID)
if f.is_valid():
if self.security_hash(request, f) != request.POST.get(self.unused_name('hash')):
return self.failed_hash(request) # Security hash failed.
return self.done(request, f.cleaned_data)
else:
return render_to_response(self.form_template,
{'form': f, 'stage_field': self.unused_name('stage'), 'state': self.state},
context_instance=RequestContext(request))
I've never tried what you're doing here with a ModelForm before, but you might be able to use the ** operator to expand your cleaned_data dictionary into the keyword arguments expected for your Registration constructor:
registration = Registration (**cleaned_data)
The constructor to your model classes take keyword arguments that Django's Model meta class converts to instance-level attributes on the resulting object. The ** operator is a calling convention that tells Python to expand your dictionary into those keyword arguments.
In other words...
What you're doing currently is tantamount to this:
registration = Registration ({'key':'value', ...})
Which is not what you want because the constructor expects keyword arguments as opposed to a dictionary that contains your keyword arguments.
What you want to be doing is this
registration = Registration (key='value', ...)
Which is analogous to this:
registration = Registration (**{'key':'value', ...})
Again, I've never tried it, but it seems like it would work as long as you aren't doing anything fancy with your form, such as adding new attributes to it that aren't expected by your Registration constructor. In that case you'd likely have to modify the items in the cleaned_data dictionary prior to doing this.
It does seem like you're losing out on some of the functionality inherent in ModelForms by going through the form preview utility, though. Perhaps you should take your use case to the Django mailing list and see if there's a potential enhancement to this API that could make it work better with ModelForms.
Edit
Short of what I've described above, you can always just extract the fields from your cleaned_data dictionary "by hand" and pass those into your Registration constructor too, but with the caveat that you have to remember to update this code as you add new fields to your model.
registration = Registration (
x=cleaned_data['x'],
y=cleaned_data['y'],
z=cleaned_data['z'],
...
)