CODEWITHSUNDEEP
pythonflaskwtforms
user1235777
user1235777

Reputation: 639

WTForms: test whether field is filled out

I'm having trouble with what I thought would be a very simple task in WTForms: checking to see if a field has had any data entered in it. It seems that the data method returns different results depending on the type of field, so I can't use it generically to test this.

I'm using this in a Flask app. In my forms declaration, I have:

title = StringField('Title')
signed = RadioField('Signed?', choices = [('Y','yes'),('N','no')])

Then, in my views.py, after an "if form.is_submitted()":

print('Title raw_data is %r' % form.title.raw_data)
print('Title data is %r' % form.title.data)
if form.title.raw_data:
    print ("Title raw data is True")
if form.title.data:
    print ("Title data is True")

 print('Signed raw_data is %r' % form.signed.raw_data)
 print('Signed data is %r' % form.signed.data)
 if form.signed.raw_data:
     print ("Signed raw data is True")
 if form.signed.data:
     print ("Signed data is True")

When I run this and fill out neither field in the form, I get:

Title raw_data is ['']
Title data is ''
Title raw data is True
Signed raw_data is []
Signed data is 'None'
Signed data is True

That is, form.title.data returns the empty string, so I can use this for a test; form.signed.data returns the string 'None', rather than None, so it fails the "if form.signed.data" test. Thus I have to use form.signed.raw_data, which returns an empty list, which is False. But I can't use raw_data in all instances, because form.title.raw_data doesn't return an empty list, it returns a list consisting of the empty string, which is not True

Is there a way I can test if any kind of field is filled out, or do I have to switch between data and raw_data depending on the kind of field? This is counterintuitive and confusing.

Upvotes: 1

Views: 3291

Answers (1)

Oluwafemi Sule
Oluwafemi Sule

Reputation: 38922

In raw_data, values for a form field are collected in a list.

You want to work with data because its value is processed to its python representation. Most fields subclassing wtforms.fields.core.Field implements their own process_formdata method which fulfills this.

Start by implementing a helper function that checks field data like so:

def is_filled(data):
   if data == None:
      return False
   if data == '':
      return False
   if data == []:
      return False
   return True

Note that data starts out set to the default value if a default value is specified in the field schema. In this case using raw_data is more correct.

def is_filled(raw_data):
   try:
       value = raw_data[0]
       if value == '':
          return False
   except (IndexError, TypeError):
       return False
   return True

Tests:

>>> is_filled(None)
False
>>> is_filled([])
False
>>> is_filled(['',]) 
False

Upvotes: 2

Related Questions