Odoo-Tutorial/advanced_loan_management/views/res_partner_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
     <!-- res partner inherit Loans -->
    <record id="res_partner_view_form_inherit" model="ir.ui.view">
        <field name="name">res.partner.view.form.inherit.loan.management</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="arch" type="xml">
            <xpath expr="//div[@name='button_box']" position="inside">
                <button name="action_view_loans" type="object"  class="oe_stat_button"
                    icon="fa-calendar">
                    <field name="loan_count" widget="statinfo" string="Loans"/>
                </button>
            </xpath>
        </field>
    </record>
</odoo>