Store .less files in database

When users customize .less files using the 'web_editor', the controller
creates a new ir.attachment for the customized file [0].

The attachment will be stored in S3 by default, which is unfortunate
since it will slow down the generation of the assets. Force storage
in the database for .less files.

Note: beware when porting this to upper versions, check the code of
web_editor, because it changed (notably less files are now scss).

[0] https://github.com/odoo/odoo/blob/11.0/addons/web_editor/controllers/main.py#L370

base_attachment_object_storage/models/ir_attachment.py

@@ -83,6 +83,12 @@ class IrAttachment(models.Model):
             '|',
             # assets are stored in 'ir.ui.view'
             ('res_model', '=', 'ir.ui.view'),
+            # less files customized through 'web_editor' are saved as
+            # attachments, in any case, we'll always want less files in DB (or
+            # in /static directories) rather than in the object storage.
+            # It seems the 'text/less' mimetype is not always correct, so
+            # rely on the url.
+            ('url', '=like', '%.less'),
             # Binary fields are stored with the name of the field in
             # 'res_field'
             # 'image' fields can be rather large and should usually
@@ -101,6 +107,10 @@ class IrAttachment(models.Model):
         because they should be fast to read as they are often displayed
         in kanbans / lists. The same for web_icon_data.
 
+        .less files customized through the "web_editor" interface must
+        be stored in DB too (normally this kind of file is stored in the
+        /static directories of modules).
+
         We store the assets locally as well. Not only for performance,
         but also because it improves the portability of the database:
         when assets are invalidated, they are deleted so we don't have
@@ -118,6 +128,9 @@ class IrAttachment(models.Model):
             # assets are stored in 'ir.ui.view'
             return True
 
+        if self.url and self.url.endswith('.less'):
+            return True
+
         # Binary fields
         if self.res_field:
             # Binary fields are stored with the name of the field in