[IMP] purchase: split compute methods

No advantage to group a search on purchase.order and another one on
account.invoice.
Avoid potential access errors if a user has access to one model but not the
other one.

Closes #25761

addons/purchase/models/res_partner.py

@@ -10,11 +10,15 @@ class res_partner(models.Model):
     _inherit = 'res.partner'
 
     @api.multi
-    def _purchase_invoice_count(self):
+    def _compute_purchase_order_count(self):
         PurchaseOrder = self.env['purchase.order']
-        Invoice = self.env['account.invoice']
         for partner in self:
             partner.purchase_order_count = PurchaseOrder.search_count([('partner_id', 'child_of', partner.id)])
+
+    @api.multi
+    def _compute_supplier_invoice_count(self):
+        Invoice = self.env['account.invoice']
+        for partner in self:
             partner.supplier_invoice_count = Invoice.search_count([('partner_id', 'child_of', partner.id), ('type', '=', 'in_invoice')])
 
     @api.model
@@ -24,7 +28,7 @@ class res_partner(models.Model):
     property_purchase_currency_id = fields.Many2one(
         'res.currency', string="Supplier Currency", company_dependent=True,
         help="This currency will be used, instead of the default one, for purchases from the current partner")
-    purchase_order_count = fields.Integer(compute='_purchase_invoice_count', string='Purchase Order Count')
-    supplier_invoice_count = fields.Integer(compute='_purchase_invoice_count', string='# Vendor Bills')
+    purchase_order_count = fields.Integer(compute='_compute_purchase_order_count', string='Purchase Order Count')
+    supplier_invoice_count = fields.Integer(compute='_compute_supplier_invoice_count', string='# Vendor Bills')
     purchase_warn = fields.Selection(WARNING_MESSAGE, 'Purchase Order', help=WARNING_HELP, default="no-message")
     purchase_warn_msg = fields.Text('Message for Purchase Order')