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
Related
I feel I'm missing the obvious but I can't work it out!
I have written a custom form (for use outside of django admin), which I want to use to create / update instances of a number of model instances as well as hold conditional fields. However I seem to be losing my conditional data.
In my view I instansiate an instance of my form and pass it into the request context:-
view.py
form = MyForm(my_bool=True, pid=7)
render(request 'my_page.html', {'form': form})
forms.py
class MyForm(forms.Form):
def __init__(self, *args, **kwargs):
my_bool = kwargs.pop('my_bool', False)
self.pid = kwargs.pop('pid', None)
super(MyForm, self).__init__(*args, **kwargs)
if my_bool:
self.fields['textbox'] = forms.CharField(max_length=256)
That all works fine and the form renders as expected. Now when I submit the form it hits the below
view.py
if request.method == 'POST':
form = MyForm(request.POST)
if form.is_valid():
# Do Stuff
My problem is that the form object in the above code does not contain my 'textbox' or 'pid' fields even though the form I submitted did. I'm certain whatever I'm doing wrong is extremely obvious but from a whole lot of googling I cant work out a simple way to instantiate a form, pass it some data about what fields I want to show as well as say the id of the model I eventually want it to update and then have access to the info I passed in the post part of the code.
The # Do Stuff part of my code is supposed to take the 'pid' I passed to the form and use that to fetch a product e.g. Product.objects.get(pk=pid), however without storing the pid in the session I cant work out how to access it from the postback.
If a validation error occurs in my form i.e. form.is_valid() returns false I render the request again passing the form I already have, that way I see the validation errors however any conditional fields I passed initially are missing and their values ignored.
Maybe I'm just going about it completely wrong and I should be doing this a different way. What I am trying to achieve is a content entry form whose fields change depending on the type of product it is passed, once filled in the form saves the data to that instance of the product.
Any help would be greatly appreciated, I've found Django to be extremely accommodating to anything I've thrown at it so far and this feels like such a common use-case that I must just be doing it wrong!
I'm on Django v1.11 & Python v3.6.
you are passing two arguments to create the form, namely my_bool and pid. But you are not passing those arguments in the POST view. In particular my_bool is None so the textbox field never gets generated. Changing
form = MyForm(request.POST)
to
form = MyForm(request.POST, my_bool=True, pid=7)
should do the trick.
I am getting the form with through a post request:
form = ReportDataForm2(req.POST)
I am trying to strip spaces from all fields by:
for element in form:
form[element] = form[element].strip()
But this does not seem to do anything.
I also tried stripping at the point where I am receiving the data:
id = form.cleaned_data['id'].strip()
Not working either.
I am new to Django so don't know how forms are treated.
How about this:
You extend the CharField class, create your own Field, and use that anytime you want to have stripped field?
class StrippedCharField(CharField):
"""Newforms CharField that strips trailing and leading spaces."""
def clean(self, value):
if value is not None:
value = value.strip()
return super(StrippedCharField, self).clean(value)
There's been a long discussion on whether form data stripping should be handled by Django or not. The discussion was resurrected recently but the actual thread started about 7 years ago
I haven't tested the code above myself. The solution was pulled from this forum discussion
A good place to validate your form fields is the clean_<fieldname>() method. <fieldname> is the name of the field you want to validate. For example, if you want to validate a field called name, you will define a clean_name() method to validate it.
An elaborate example:
class MyForm(forms.Form):
text = forms.CharField(...)
...
def clean_text(self):
stripped_text = self.cleaned_data['text'].strip()
# do some other validation if you want...
return stripped_text
Apart from stripping, you can do all sorts of validation there.
See docs for more on validation.
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.
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/
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'],
...
)