[IMP] Add the possibility to have more than 1 vehicle by PO

    Initially, there was only one vehicle for one PO.
    Now, if the vehicle is set on the PO, all the PO lines are related to this vehicle
    But if the vehicle is not set on the PO, the user can decide to have different vehicles on every line.
    Use case is a grouped purchase of several items for several vehicles.

fleet_vehicle_purchase/models/__init__.py

@@ -1,2 +1,3 @@
 from . import purchase_order
 from . import fleet_vehicle
+from . import purchase_order_line

fleet_vehicle_purchase/models/fleet_vehicle.py

@@ -15,8 +15,16 @@ class FleetVehicle(models.Model):
 
     @api.depends("purchase_order_ids")
     def _compute_purchase_order_count(self):
-        for record in self:
-            record.purchase_order_count = len(record.purchase_order_ids)
+        orders = self.env["purchase.order"].read_group(
+            [("fleet_vehicle_id", "in", self.ids)],
+            ["fleet_vehicle_id"],
+            ["fleet_vehicle_id"],
+        )
+        mapped_data = {
+            po["fleet_vehicle_id"][0]: po["fleet_vehicle_id_count"] for po in orders
+        }
+        for rec in self:
+            rec.purchase_order_count = mapped_data.get(rec.id, 0)
 
     def action_view_purchase_orders(self):
         self.ensure_one()

fleet_vehicle_purchase/models/purchase_order.py

@@ -9,13 +9,3 @@ class PurchaseOrder(models.Model):
     _inherit = "purchase.order"
 
     fleet_vehicle_id = fields.Many2one("fleet.vehicle", string="Vehicle")
-
-
-class PurchaseOrderLine(models.Model):
-
-    _inherit = "purchase.order.line"
-
-    def _prepare_account_move_line(self, move=False):
-        result = super()._prepare_account_move_line(move)
-        result["vehicle_id"] = self.order_id.fleet_vehicle_id.id
-        return result

fleet_vehicle_purchase/views/purchase_order.xml

@@ -11,6 +11,17 @@
             <field name="partner_ref" position="after">
                 <field name="fleet_vehicle_id" />
             </field>
+            <xpath
+                expr="//sheet//notebook//page[@name='products']//tree//field[@name='date_planned']"
+                position="after"
+            >
+                <field name="fleet_vehicle_from_po" invisible="1" />
+                <field
+                    name="fleet_vehicle_id"
+                    optional="hide"
+                    attrs="{'readonly': [('fleet_vehicle_from_po', '=', True)]}"
+                />
+            </xpath>
         </field>
     </record>