I have try to hide discount field in invoice form by xpath. However it doesn't work.
The following is my code :
<odoo>
<data>
<record model="ir.ui.view" id="hidden_discount">
<field name="name">account.invoice.hidden.discount</field>
<field name="model">account.invoice</field>
<field name="inherit_id" ref="account.invoice_form"/>
<field name="arch" type="xml">
<xpath expr="//field[@name='discount']" position="attributes">
<attribute name="invisible">True</attribute>
</xpath>
</field>
</record>
</data>
</odoo>
Do you have any solution or suggestion?