sale_usability: Add sale_ids and sale_count on account.invoice

Show sale_line_ids on invoice line form view

sale_usability/account_invoice.py

@@ -2,13 +2,46 @@
 # @author Alexis de Lattre <alexis.delattre@akretion.com>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import models
+from odoo import api, fields, models
 from collections import OrderedDict
 
 
 class AccountInvoice(models.Model):
     _inherit = 'account.invoice'
 
+    # sale_ids is kind of the symetric field of invoice_ids on sale.order
+    sale_ids = fields.Many2many(
+        'sale.order', string='Sale Orders', compute="_compute_sale_ids",
+        readonly=True, copy=False)
+    sale_count = fields.Integer(
+        string='Sale Order Count', compute='_compute_sale_ids', readonly=True)
+
+    @api.depends('invoice_line_ids.sale_line_ids')
+    def _compute_sale_ids(self):
+        for invoice in self:
+            if invoice.type == 'out_invoice':
+                sales = invoice.invoice_line_ids.mapped('sale_line_ids').\
+                    mapped('order_id')
+                invoice.sale_ids = sales.ids
+                invoice.sale_count = len(sales.ids)
+            else:
+                invoice.sale_ids = []
+                invoice.sale_count = 0
+
+    def show_sale_orders(self):
+        self.ensure_one()
+        action = self.env.ref('sale.action_orders').read()[0]
+        sales = self.sale_ids
+        if len(sales) > 1:
+            action['domain'] = [('id', 'in', sales.ids)]
+        else:
+            action.update({
+                'res_id': sales.id,
+                'view_mode': 'form,tree,kanban,calendar,pivot,graph,activity',
+                'views': False,
+                })
+        return action
+
     def py3o_lines_layout_groupby_order(self, subtotal=True):
         # This method is an alternative to the method py3o_lines_layout()
         # defined above: you just have to change the call in the invoice