class Meta:
    model = diliModels.Proposal
fields = ('id', 'my_proposal_side', 'my_proposal_type',
    'number_of_participants', 'cost_per_participants',
    'minimum_dollar_commitment', 'commercial_terms', 'is_publicly_visible',
    'is_anonymous', 'is_republish', 'name', 'my_delivery_type',
    'my_survey_method', 'number_of_unique_contacts', 'availability_start',
    'availability_end', 'location_country', 'location_city',
    'location_state', 'description', 'desired_meetings')

def validate(self, attrs):
    pass
How to validate a model in django rest framework?