fix(exportable): v17 fields are sometimes non exportable

[martintamare]

We are upgrading to Odoo 17 and saw a regression.
Some fields are specifically marked as exportable=False in the Odoo codebase.
This patch allow to check for the existence of this parameter and simply skip unnecessary fields.

[sebalix]

From what I read, this exportable parameter set on fields is only used by the route /web/export/get_fields in addons/web/controllers/export.py file. This route seems used by Odoo web client only for the export feature (when exporting a list of records), but it doesn't prevent to read that field in other contexts.

For instance, <ir.module.module>.account_templates is not exportable, but there is no issue to access it through RPC:

>>> import odoorpc
>>> from pprint import pprint as pp
>>> odoo = odoorpc.ODOO(...)
>>> odoo.login(...)
>>> mod_ids = odoo.env["ir.module.module"].search([("name", "=", "account")])
>>> mod = odoo.env["ir.module.module"].browse(42)
>>> pp(mod.account_templates)
{'generic_coa': {'country_code': None,
                 'country_id': None,
                 'installed': True,
                 'module': 'account',
                 'name': 'Generic Chart Template',
                 'parent': None,
                 'sequence': 1,
                 'visible': True}}

What error did you encounter exactly?

[martintamare]

We are now running version 19 in production.
To my knowledge I dont see the issue anymore. But we are using of patch code.
I will investigate and get back to you on this