please correct my javascript code.in xml file
template.xml

<template id="openeducat_create_subject_registration" name="Create Subject Registration">
        <t t-call="portal.portal_layout">

            <t t-call="portal.portal_searchbar">
                <t t-set="title">Subject Registration Form</t>
            </t>
            <t t-if="not student_id">
                <p>There are currently no information for your account!!!</p>
            </t>

            <div t-if="student_id" style="background-color:white; padding: 20px 40px 20px 40px;">
                <div class="mt32">
                    <form action="/subject/registration/submit" method="post" role="form"
                          enctype="multipart/form-data">
                        <input type="hidden" name="csrf_token" t-att-value="request.csrf_token()"/>
                        <div class="row col-md-12">
                            <div class="row col-md-6">
                                <input type="hidden" name="student_id" t-attf-class="form-control"
                                       t-att-value="student_id.id"/>
                                <div class="col-md-4 mt8">
                                    <lable for="course_id">Course:</lable>
                                </div>
                                <div class="col-md-8">
                                    <select id="course_dropdown" class="form-control" name="course_id"
                                            onchange="myFunction()">
                                        <option value="" class="disabled selected">
                                            <lable>Select your option</lable>
                                        </option>
                                        <t t-foreach="course" t-as="course_id">
                                            <option t-att-value="course_id.id">
                                                <t t-esc="course_id.name"/>
                                            </option>
                                        </t>
                                    </select>
                                </div>
                                <script>
                                    function myFunction() {

                                    odoo.define("op.batch", function (require) {

                                    var rpc = require('web.rpc');
                                    var course = document.getElementById("course_dropdown");

                                    rpc.query({

                                    model: 'op.batch',

                                    }).then(function (data) {

                                    for(i in data){
                                    alert(i);
                                    document.getElementById("batch_id").value = i.name;}

                                    });

                                    });

                                    }
                                </script>
                                <div class="col-md-4 mt16">
                                    <lable for="batch_id">Batch:</lable>
                                </div>
                                <div class="col-md-8 mt8">
                                    <select class="form-control" name="batch_id">
                                        <option value="" class="disabled selected">
                                            <lable>Select your option</lable>
                                        </option>
                                        <option>
                                            <t id="batch_id" t-esc="batch_id"/>
                                        </option>
                                    </select>
                                </div>
                            </div>
                            <div class="row col-md-6">
                                <div class="col-md-6 mt8">
                                    <lable for="min_unit_load">Minimum Unit Load:</lable>
                                </div>
                                <div class="col-md-6">
                                    <input type="number" name="min_unit_load" t-attf-class="form-control"
                                           t-attf-value="student_id.min_unit_load"/>
                                </div>
                                <div class="col-md-6 mt16">
                                    <lable for="max_unit_load">Maximum Unit Load:</lable>
                                </div>
                                <div class="col-md-6 mt8">
                                    <input type="number" name="max_unit_load" t-attf-class="form-control"
                                           t-attf-value="student_id.max_unit_load"/>
                                </div>
                            </div>
                        </div>
                        <div class="mt32"/>
                        <div t-if="user_id.sudo().is_student" class="row col-md-12">
                            <div class="col-md-2 mt8">
                                <lable for="compulsory_subject_ids">Compulsory Subjects:</lable>
                            </div>
                            <div class="col-md-10" style="padding-left: 5px;">
                                <select class="form-control js-example-basic-multiple subjects"
                                        name="compulsory_subject_ids" multiple="True" required="1">
                                    <t t-foreach="subjects or []" t-as="subject">
                                        <t t-if="subject.subject_type == 'compulsory'">
                                            <option t-att-value="subject.id">
                                                <t t-esc="subject.name"/>
                                            </option>
                                        </t>
                                    </t>
                                </select>
                            </div>
                        </div>
                        <div t-if="user_id.sudo().is_student" class="row mt8 col-md-12">
                            <div class="col-md-2 mt8">
                                <lable for="elective_subject_ids">Elective Subjects:</lable>
                            </div>
                            <div class="col-md-10" style="padding-left: 5px;">
                                <select class="form-control js-example-basic-multiple subjects"
                                        name="compulsory_subject_ids" multiple="True" required="1">
                                    <t t-foreach="subjects or []" t-as="subject">
                                        <t t-if="subject.subject_type == 'elective'">
                                            <option t-att-value="subject.id">
                                                <t t-esc="subject.name"/>
                                            </option>
                                        </t>
                                    </t>
                                </select>
                            </div>
                        </div>
                        <div class="clearfix mb16 mt16 row col-md-12">
                            <div class="col-md-4">
                                <button type="submit" class="btn btn-primary">
                                    SUBMIT
                                    <span class="fa fa-long-arrow-right"/>
                                </button>
                            </div>
                        </div>
                    </form>
                </div>
            </div>
        </t>
    </template>

model.py file all fields are available here.

 class OpSubjectRegistration(models.Model):
         _name = "op.subject.registration"
         _inherit = ["mail.thread"]

         name = fields.Char('Name', readonly=True, default='New')
         student_id = fields.Many2one('op.student', 'Student', required=True,
                             track_visibility='onchange')
         course_id = fields.Many2one('op.course', 'Course', required=True,
                            track_visibility='onchange')
         batch_id = fields.Many2one('op.batch', 'Batch', required=True,
                           track_visibility='onchange')
         compulsory_subject_ids = fields.Many2many(
    'op.subject', 'subject_compulsory_rel',
    'register_id', 'subject_id', string="Compulsory Subjects",
    readonly=True)
         elective_subject_ids = fields.Many2many(
    'op.subject', string="Elective Subjects")
         state = fields.Selection([
    ('draft', 'Draft'), ('submitted', 'Submitted'),
    ('approved', 'Approved'), ('rejected', 'Rejected')],
    default='draft', string='state', copy=False,
    track_visibility='onchange')
        max_unit_load = fields.Float('Maximum Unit Load',
                             track_visibility='onchange')
        min_unit_load = fields.Float('Minimum Unit Load',
                             track_visibility='onchange')

template.xml file "student subject registration form" if i select "course" baesd on course field value batch shoul be update.
    <template id="openeducat_create_subject_registration" name="Create Subject Registration">
        <t t-call="portal.portal_layout">

            <t t-call="portal.portal_searchbar">
                <t t-set="title">Subject Registration Form</t>
            </t>
            <t t-if="not student_id">
                <p>There are currently no information for your account!!!</p>
            </t>

            <div t-if="student_id" style="background-color:white; padding: 20px 40px 20px 40px;">
                <div class="mt32">
                    <form action="/subject/registration/submit" method="post" role="form"
                          enctype="multipart/form-data">
                        <input type="hidden" name="csrf_token" t-att-value="request.csrf_token()"/>
                        <div class="row col-md-12">
                            <div class="row col-md-6">
                                <input type="hidden" name="student_id" t-attf-class="form-control"
                                       t-att-value="student_id.id"/>
                                <div class="col-md-4 mt8">
                                    <lable for="course_id">Course:</lable>
                                </div>
                                <div class="col-md-8">
                                    <select id="course_dropdown" class="form-control" name="course_id"
                                            onchange="myFunction()">
                                        <option value="" class="disabled selected">
                                            <lable>Select your option</lable>
                                        </option>
                                        <t t-foreach="course" t-as="course_id">
                                            <option t-att-value="course_id.id">
                                                <t t-esc="course_id.name"/>
                                            </option>
                                        </t>
                                    </select>
                                </div>
                                <script>
                                    function myFunction() {

                                    odoo.define("op.batch", function (require) {

                                    var rpc = require('web.rpc');
                                    var course = document.getElementById("course_dropdown");

                                    rpc.query({

                                    model: 'op.batch',

                                    }).then(function (data) {

                                    for(i in data){
                                    alert(i);
                                    document.getElementById("batch_id").value = i.name;}

                                    });

                                    });

                                    }
                                </script>
                                <div class="col-md-4 mt16">
                                    <lable for="batch_id">Batch:</lable>
                                </div>
                                <div class="col-md-8 mt8">
                                    <select class="form-control" name="batch_id">
                                        <option value="" class="disabled selected">
                                            <lable>Select your option</lable>
                                        </option>
                                        <option>
                                            <t id="batch_id" t-esc="batch_id"/>
                                        </option>
                                    </select>
                                </div>
                            </div>
                            <div class="row col-md-6">
                                <div class="col-md-6 mt8">
                                    <lable for="min_unit_load">Minimum Unit Load:</lable>
                                </div>
                                <div class="col-md-6">
                                    <input type="number" name="min_unit_load" t-attf-class="form-control"
                                           t-attf-value="student_id.min_unit_load"/>
                                </div>
                                <div class="col-md-6 mt16">
                                    <lable for="max_unit_load">Maximum Unit Load:</lable>
                                </div>
                                <div class="col-md-6 mt8">
                                    <input type="number" name="max_unit_load" t-attf-class="form-control"
                                           t-attf-value="student_id.max_unit_load"/>
                                </div>
                            </div>
                        </div>
                        <div class="mt32"/>
                        <div t-if="user_id.sudo().is_student" class="row col-md-12">
                            <div class="col-md-2 mt8">
                                <lable for="compulsory_subject_ids">Compulsory Subjects:</lable>
                            </div>
                            <div class="col-md-10" style="padding-left: 5px;">
                                <select class="form-control js-example-basic-multiple subjects"
                                        name="compulsory_subject_ids" multiple="True" required="1">
                                    <t t-foreach="subjects or []" t-as="subject">
                                        <t t-if="subject.subject_type == 'compulsory'">
                                            <option t-att-value="subject.id">
                                                <t t-esc="subject.name"/>
                                            </option>
                                        </t>
                                    </t>
                                </select>
                            </div>
                        </div>
                        <div t-if="user_id.sudo().is_student" class="row mt8 col-md-12">
                            <div class="col-md-2 mt8">
                                <lable for="elective_subject_ids">Elective Subjects:</lable>
                            </div>
                            <div class="col-md-10" style="padding-left: 5px;">
                                <select class="form-control js-example-basic-multiple subjects"
                                        name="compulsory_subject_ids" multiple="True" required="1">
                                    <t t-foreach="subjects or []" t-as="subject">
                                        <t t-if="subject.subject_type == 'elective'">
                                            <option t-att-value="subject.id">
                                                <t t-esc="subject.name"/>
                                            </option>
                                        </t>
                                    </t>
                                </select>
                            </div>
                        </div>
                        <div class="clearfix mb16 mt16 row col-md-12">
                            <div class="col-md-4">
                                <button type="submit" class="btn btn-primary">
                                    SUBMIT
                                    <span class="fa fa-long-arrow-right"/>
                                </button>
                            </div>
                        </div>
                    </form>
                </div>
            </div>
        </t>
    </template>
model.py file all fields are available here.
    class OpSubjectRegistration(models.Model):
         _name = "op.subject.registration"
         _inherit = ["mail.thread"]

         name = fields.Char('Name', readonly=True, default='New')
         student_id = fields.Many2one('op.student', 'Student', required=True,
                             track_visibility='onchange')
         course_id = fields.Many2one('op.course', 'Course', required=True,
                            track_visibility='onchange')
         batch_id = fields.Many2one('op.batch', 'Batch', required=True,
                           track_visibility='onchange')
         compulsory_subject_ids = fields.Many2many(
    'op.subject', 'subject_compulsory_rel',
    'register_id', 'subject_id', string="Compulsory Subjects",
    readonly=True)
         elective_subject_ids = fields.Many2many(
    'op.subject', string="Elective Subjects")
         state = fields.Selection([
    ('draft', 'Draft'), ('submitted', 'Submitted'),
    ('approved', 'Approved'), ('rejected', 'Rejected')],
    default='draft', string='state', copy=False,
    track_visibility='onchange')
        max_unit_load = fields.Float('Maximum Unit Load',
                             track_visibility='onchange')
        min_unit_load = fields.Float('Minimum Unit Load',
                             track_visibility='onchange')
please help me to do this i am stucking at javascript code how to do this using javascript how to take model records and perform operations.
controller.py ....................................
@http.route('/subject/registration/create/', type='http', auth='public', website=True)
def subject_registration(self, **kw):
    students = request.env['op.student'].sudo().search([('user_id', '=', request.session.uid)])
    for student in students:
        student_id = request.env['op.subject.registration'].sudo().search([('student_id', '=', student.name)])
        course = request.env['op.course'].sudo().search([])
        subjects = request.env['op.subject'].sudo().search([])
        values = {
            'student_id': student_id,
            'course': course,
            'subjects': subjects,
        }
        return request.render("portal_student.openeducat_create_subject_registration", values)