espaço reservado em forma de modelo
class LoginForm(forms.Form):
username = forms.CharField(label='username')
password = forms.CharField(label='password')
def __init__(self, *args, **kwargs):
super(LoginForm, self).__init__(*args, **kwargs)
self.fields['username'].widget.attrs['placeholder'] = 'username'
self.fields['password '].widget.attrs['placeholder'] = 'password'
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