[12.0][FIX] account_invoice_triple_discount: subtotal computation

account_invoice_triple_discount/__manifest__.py

@@ -16,6 +16,7 @@
     ],
     'data': [
         'views/account_invoice_view.xml',
+        'views/res_partner_views.xml',
     ],
     'installable': True,
 }

account_invoice_triple_discount/models/__init__.py

@@ -1,3 +1,5 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
+from . import line_triple_discount
 from . import account_invoice
+from . import res_partner

account_invoice_triple_discount/models/account_invoice.py

@@ -3,59 +3,42 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
 from odoo import api, fields, models
-from odoo.addons import decimal_precision as dp
 
 
 class AccountInvoice(models.Model):
     _inherit = "account.invoice"
 
+    discounting_type = fields.Selection(
+        related='partner_id.discounting_type',
+    )
+
     def get_taxes_values(self):
-        vals = {}
-        for line in self.invoice_line_ids:
-            vals[line] = {
-                'price_unit': line.price_unit,
-                'discount': line.discount,
-            }
-            price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
-            line.update({
-                'price_unit': price_unit,
-                'discount': 0.0,
-            })
-        tax_grouped = super(AccountInvoice, self).get_taxes_values()
-        for line in self.invoice_line_ids:
-            line.update(vals[line])
+        lines = self.invoice_line_ids
+        prev_values = lines.triple_discount_preprocess()
+        tax_grouped = super().get_taxes_values()
+        lines.triple_discount_postprocess(prev_values)
         return tax_grouped
 
+    @api.onchange('partner_id', 'company_id')
+    def _onchange_partner_id(self):
+        self.ensure_one()
+        res = super()._onchange_partner_id()
+        partner_discounting_type = self.partner_id.discounting_type
+        if partner_discounting_type:
+            self.invoice_line_ids.update({
+                'discounting_type': partner_discounting_type,
+            })
+        return res
 
-class AccountInvoiceLine(models.Model):
-    _inherit = "account.invoice.line"
 
-    discount2 = fields.Float(
-        'Discount 2 (%)',
-        digits=dp.get_precision('Discount'),
-    )
-    discount3 = fields.Float(
-        'Discount 3 (%)',
-        digits=dp.get_precision('Discount'),
-    )
+class AccountInvoiceLine(models.Model):
+    _name = "account.invoice.line"
+    _inherit = ["line.triple_discount.mixin", "account.invoice.line"]
 
     @api.multi
-    @api.depends('discount2', 'discount3')
+    @api.depends('discount2', 'discount3', 'discounting_type')
     def _compute_price(self):
         for line in self:
-            prev_price_unit = line.price_unit
-            prev_discount = line.discount
-            price_unit = line.price_unit * (1 - (line.discount or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount2 or 0.0) / 100.0)
-            price_unit *= (1 - (line.discount3 or 0.0) / 100.0)
-            line.update({
-                'price_unit': price_unit,
-                'discount': 0.0,
-            })
+            prev_values = line.triple_discount_preprocess()
             super(AccountInvoiceLine, line)._compute_price()
-            line.update({
-                'price_unit': prev_price_unit,
-                'discount': prev_discount,
-            })
+            line.triple_discount_postprocess(prev_values)

account_invoice_triple_discount/models/line_triple_discount.py

@@ -0,0 +1,111 @@
+# Copyright 2017 Tecnativa - David Vidal
+# Copyright 2017 Tecnativa - Pedro M. Baeza
+# Copyright 2021 Simone Rubino - Agile Business Group
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
+
+from odoo import api, fields, models
+from odoo.addons import decimal_precision as dp
+
+
+class LineTripleDiscount (models.AbstractModel):
+    _name = "line.triple_discount.mixin"
+    _description = "Add triple discount fields and logic"
+
+    discount = fields.Float()
+    discount2 = fields.Float(
+        'Discount 2 (%)',
+        digits=dp.get_precision('Discount'),
+    )
+    discount3 = fields.Float(
+        'Discount 3 (%)',
+        digits=dp.get_precision('Discount'),
+    )
+    discounting_type = fields.Selection(
+        string="Discounting type",
+        selection=[
+            ('additive', 'Additive'),
+            ('multiplicative', 'Multiplicative'),
+        ],
+        default="multiplicative",
+        required=True,
+        help="Specifies whether discounts should be additive "
+        "or multiplicative.\nAdditive discounts are summed first and "
+        "then applied.\nMultiplicative discounts are applied sequentially.\n"
+        "Multiplicative discounts are default",
+    )
+
+    _sql_constraints = [
+        ('discount2_limit', 'CHECK (discount2 <= 100.0)',
+         'Discount 2 must be lower than 100%.'),
+        ('discount3_limit', 'CHECK (discount3 <= 100.0)',
+         'Discount 3 must be lower than 100%.'),
+    ]
+
+    def _get_final_discount(self):
+        self.ensure_one()
+        if self.discounting_type == "additive":
+            return self._additive_discount()
+        elif self.discounting_type == "multiplicative":
+            return self._multiplicative_discount()
+
+    def _additive_discount(self):
+        self.ensure_one()
+        discount = sum(
+            [getattr(self, x) or 0.0 for x in self._discount_fields()]
+        )
+        if discount <= 0:
+            return 0
+        elif discount >= 100:
+            return 100
+        return discount
+
+    def _multiplicative_discount(self):
+        self.ensure_one()
+        discounts = [1 - (self[x] or 0.0) / 100
+                     for x in self._discount_fields()]
+        final_discount = 1
+        for discount in discounts:
+            final_discount *= discount
+        return 100 - final_discount * 100
+
+    def _discount_fields(self):
+        return ['discount', 'discount2', 'discount3']
+
+    @api.multi
+    def triple_discount_preprocess(self):
+        """Save the values of the discounts in a dictionary,
+        to be restored in postprocess.
+        Resetting discount2 and discount3 to 0.0 avoids issues if
+        this method is called multiple times.
+        Updating the cache provides consistency through recomputations."""
+        prev_values = dict()
+
+        # The newly computed discount might have
+        # more digits than allowed from field's precision,
+        # so let's increase it just for saving it correctly in cache
+        discount_field = self._fields['discount']
+        discount_original_digits = discount_field._digits
+        discount_field._digits = (16, 10)
+
+        for line in self:
+            prev_values[line] = dict(
+                discount=line.discount,
+                discount2=line.discount2,
+                discount3=line.discount3,
+            )
+            line.update({
+                'discount': line._get_final_discount(),
+                'discount2': 0.0,
+                'discount3': 0.0
+            })
+
+        # Restore discount field's precision
+        discount_field._digits = discount_original_digits
+        return prev_values
+
+    @api.model
+    def triple_discount_postprocess(self, prev_values):
+        """Restore the discounts of the lines in the dictionary prev_values.
+        Updating the cache provides consistency through recomputations."""
+        for line, prev_vals_dict in list(prev_values.items()):
+            line.update(prev_vals_dict)

account_invoice_triple_discount/models/res_partner.py

@@ -0,0 +1,24 @@
+#  Copyright 2021 Simone Rubino - Agile Business Group
+#  License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from odoo import fields, models
+
+
+class ResPartner (models.Model):
+    _inherit = 'res.partner'
+
+    discounting_type = fields.Selection(
+        string="Discounting type",
+        selection=[
+            ('additive', 'Additive'),
+            ('multiplicative', 'Multiplicative'),
+        ],
+        default="multiplicative",
+        required=True,
+        help="""
+        Specifies whether discounts should be additive or multiplicative.
+        Additive discounts are summed first and then applied.
+        Multiplicative discounts (default) are applied sequentially.
+        This type of discount will be the default for this partner's invoices.
+        """,
+    )

account_invoice_triple_discount/tests/test_invoice_triple_discount.py

@@ -83,3 +83,52 @@ def test_02_discounts_multiple_lines(self):
         self.invoice_line1.discount = 50.0
         self.invoice._onchange_invoice_line_ids()
         self.assertEqual(self.invoice.amount_total, 365.0)
+
+    def test_03_discounts(self):
+        """ Tests discounts in edge case """
+        invoice = self.env['account.invoice'].create({
+            'name': "Test Customer Invoice",
+            'journal_id': self.env['account.journal'].search(
+                [('type', '=', 'sale')])[0].id,
+            'partner_id': self.partner.id,
+            'account_id': self.account.id,
+            'invoice_line_ids': [(0, 0, {
+                'name': 'Line 1',
+                'price_unit': 25.0,
+                'account_id': self.account.id,
+                'quantity': 65,
+                'discount': 50,
+                'discount2': 13,
+                'discount3': 0,
+            })],
+        })
+        self.assertEqual(invoice.invoice_line_ids.price_subtotal, 706.88)
+
+    def test_increased_precision(self):
+        """
+        Check that final discount is computed correctly
+        when final discount's precision exceeds
+        discount field's allowed precision.
+        """
+        invoice_line = self.invoice_line1
+        discount_field = invoice_line._fields['discount']
+        self.assertEqual(discount_field.digits[1], 2)
+        invoice_line.discount = 45.0
+        invoice_line.discount2 = 10.0
+        invoice_line.discount3 = 5.0
+
+        self.assertAlmostEqual(
+            invoice_line._get_final_discount(),
+            52.975,
+            places=3,
+        )
+        invoice_line.triple_discount_preprocess()
+
+        # Check that the line's discount still has all the 3 digits
+        self.assertAlmostEqual(
+            invoice_line.discount,
+            52.975,
+            places=3,
+        )
+        # Check that field's precision is not changed
+        self.assertEqual(discount_field.digits[1], 2)

account_invoice_triple_discount/views/account_invoice_view.xml

@@ -6,10 +6,17 @@
         <field name="model">account.invoice</field>
         <field name="inherit_id" ref="account.invoice_form"/>
         <field name="arch" type="xml">
+            <field name="partner_id" position="after">
+                <field name="discounting_type" invisible="True"/>
+            </field>
+            <field name="invoice_line_ids" position="attributes">
+                <attribute name="context">{'type': type, 'journal_id': journal_id, 'default_invoice_id': id, 'default_discounting_type': discounting_type}</attribute>
+            </field>
             <xpath expr="//field[@name='invoice_line_ids']//tree//field[@name='discount']"
                    position="after">
                 <field name="discount2" groups="base.group_no_one"/>
                 <field name="discount3" groups="base.group_no_one"/>
+                <field name="discounting_type" groups="base.group_no_one"/>
             </xpath>
         </field>
     </record>
@@ -24,6 +31,7 @@
                    position="after">
                 <field name="discount2" groups="base.group_no_one"/>
                 <field name="discount3" groups="base.group_no_one"/>
+                <field name="discounting_type" groups="base.group_no_one"/>
             </xpath>
         </field>
     </record>

account_invoice_triple_discount/views/res_partner_views.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright 2021 Simone Rubino - Agile Business Group
+  License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+  -->
+
+<odoo>
+    <record id="view_partner_property_form" model="ir.ui.view">
+        <field name="name">Add triple discount fields</field>
+        <field name="model">res.partner</field>
+        <field name="inherit_id" ref="account.view_partner_property_form"/>
+        <field name="arch" type="xml">
+            <page name="accounting" position="inside">
+                <group name="triple_discount">
+                    <field name="discounting_type"/>
+                </group>
+            </page>
+        </field>
+    </record>
+</odoo>