hr_timesheet_invoiceable

hr_timesheet.py

# coding: utf-8
from odoo import fields, models, api


class HrTimesheetInvoiceFactor(models.Model):

    _name = "hr_timesheet_invoice.factor"
    _description = "Invoice Rate"
    _order = 'factor'

    name = fields.Char('Internal Name', required=True, translate=True)
    customer_name = fields.Char('Name', help="Label for the customer")
    factor = fields.Float(
        'Discount (%)',
        default=0.0,
        help="Discount in percentage")


class AccountAnalyticLine(models.Model):

    _inherit = 'account.analytic.line'

    to_invoice = fields.Many2one(
        'hr_timesheet_invoice.factor',
        'Invoiceable',
        default=lambda s: s.env['hr_timesheet_invoice.factor'].search(
            [], order='factor asc', limit=1),
        help="It allows to set the discount while making invoice, keep"
        " empty if the activities should not be invoiced.")

    invoiceables_hours = fields.Float(
        'Invoiceable Hours',
        compute="_compute_invoiceables_hours",
        help='Total hours to charge')

    invoice_id = fields.Many2one(
        'account.invoice',
        'Invoice',
        ondelete="set null",
        copy=False)

    @api.depends('to_invoice', 'unit_amount')
    def _compute_invoiceables_hours(self):
        for line in self:
            hours = line.unit_amount
            if line.to_invoice:
                hours -= (hours * line.to_invoice.factor / 100.0)
            line.invoiceables_hours = hours

hr_timesheet.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <record id="account_analytic_line_invoiceable_lines" model="ir.ui.view">
            <field name="name">account.analytic.line.invoiceable.lines</field>
            <field name="model">account.analytic.line</field>
            <field name="inherit_id" ref="hr_timesheet.hr_timesheet_line_tree"/>
            <field name="arch" type="xml">
                <xpath expr="//field[@name='unit_amount']" position="after">
                    <field name="to_invoice"/>
                    <field name="invoiceables_hours" sum="Total invoiceable time" widget="float_time"/>
                </xpath>
            </field>
        </record>
        <record id="account_analytic_line_invoiceable_lines2" model="ir.ui.view">
            <field name="name">account.analytic.line.invoiceable.lines2</field>
            <field name="model">account.analytic.line</field>
            <field name="inherit_id" ref="timesheet_grid.view_timesheet_list"/>
            <field name="arch" type="xml">
                <xpath expr="//field[@name='unit_amount']" position="after">
                    <field name="to_invoice"/>
                    <field name="invoiceables_hours" sum="Total invoiceable time" widget="float_time"/>
                </xpath>
            </field>
        </record>
    </data>

Cool, thanks!