[FIX] lunch: Cache lunch product images

Images of the lunch dashboard are not cached by the browser.

closes odoo/odoo#47427

X-original-commit: fec2e2a4
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/lunch/report/lunch_product_report.py

 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import fields, models, tools
+from odoo import api, fields, models, tools
 from odoo.osv import expression
 
 
@@ -41,6 +41,17 @@ class LunchProductReport(models.Model):
             else:
                 product_r.image_128 = False
 
+    def compute_concurrency_field(self):
+        """Image caching is based on the `__last_update` field (=self.CONCURRENCY_CHECK_FIELD)
+        But the image is never cached by the browser because the value fallbacks to
+        `now` when access logging is disabled. This override sets a "real" value based on the
+        product or category last update.
+        """
+        for report in self:
+            product_last_update = report.product_id[self.CONCURRENCY_CHECK_FIELD]
+            category_last_update = report.category_id[self.CONCURRENCY_CHECK_FIELD]
+            report[self.CONCURRENCY_CHECK_FIELD] = max(product_last_update, category_last_update)
+
     def _compute_is_available_at(self):
         """
             Is available_at is always false when browsing it