i want to add a filter name "product" as exactly the default filter in product model. i have given a picture of the filter which i want[the filter which is in add custom filter]. any help will be appreciated.
For adding a new custom filter you should inherit the search view of the action like below:
<record id="pos_order_view_search_inherit_product_filter" model="ir.ui.view">
<field name="name">pos.order.search.inherit.product.filter</field>
<field name="model">pos.order</field>
<field name="mode">primary</field>
<field name="inherit_id" ref="view_pos_order_search"/>
<field name="arch" type="xml">
<xpath expr="//search" position="inside">
<field name="lines" string="Product" filter_domain="[('lines.product_id', 'ilike', self)]"/>
</xpath>
</field>
</record>
This will add the option to search by product name in the search bar.
You can create a custom addon to do this, or just create a view from the backend (Settings/Technical/Views menu).