Don't allow submit form when fields in blank Django Python -

i know how prevent user of submitting form when of fields left in blank, (i know how validate on server side, i'm looking answer on client side think) thank you!

**

update

** form, combines fields class created (prestamista) , adds 3 fields user class, managed require attribute in last 3 adding widget, don't know how set require argument others prestamista class

class myregistrationform(modelform):     class meta:         model= prestamista         fields = ['trabaja', 'sueldo', 'edad']         fields_required = ['trabaja', 'sueldo', 'edad']     username = forms.charfield(max_length= 30, required=true, widget=forms.textinput(attrs={'required': 'true'}))     password = forms.charfield(required=true, widget = forms.passwordinput(attrs={'required': 'true'}))      email = forms.emailfield(widget=forms.textinput(attrs={'class': "emailfields",'required': 'true'})) 

as patrick.ryan93 pointed out can use required inputs, instead of rendering forms can add widget form object.

somefield = forms.textfield(     required=true,     widget=forms.textinput(attrs={'required': 'true'}), ) 

should render

<input type="text" name=... required> 

which won't submitted unless fields have value: jsfiddle