How to filter in odoo front end?

Here is my code:

<t t-set="cates" t-value="website.get_shop_category_of_product()"/>
                                    <t t-if="cates">
                                        <select id="categ" required="True" class="form-control">
                                            <t t-foreach="cates" t-as="c">
                                               <option t-attf-value="#{c.id}"><t t-esc="c.name"/>

                                               </option>
                                            </t>
                                        </select>
                                    </t>

How to filter in category of prouduct? get_shop_category_of_product function is return all website category of product. Help i need any solution and idea.