I created a controller to fetch records from students table for logged parent user. 

class Webopeneducat(http.Controller):
    @http.route('/my/child', auth='user', website=True)
    def list_students(self, **kw):
        current_user = http.request.env.context.get('uid')
        students = request.env['op.student'].sudo().search([('parent_ids.user_id', '=', current_user)])
        assignments = request.env['op.assignment'].sudo().search(['student[].student_id', 'in', 'allocation_ids'])
        print("students---", students)
        return http.request.render('web_openeducat.index', {

            'students': students,
            'assignments': assignments
            })

I want to obtain records of only logged user. I can get students info from students model, but i also want assignments info of that students from assignments model. how can i fetch data from multiple models at once?