1. Installation

This is a technical library module. It does not provide end-user features out of the box but serves as a dependency for other modules.

• Ensure the module l10n_country_filter is available in your addons path.
• Add it as a dependency in your module's manifest:

'depends': [
    'l10n_country_filter', 
    # ... other dependencies
],
                            

2. Code Implementation

Implement the filter in your model's _get_view method. This ensures fields are hidden dynamically before the view is served to the user.

Step-by-Step Example:

Suppose you want to hide the l10n_pe_vat_code field and the l10n_pe_group group for companies that are NOT in Peru.

from odoo import models, api

class ResPartner(models.Model):
    _inherit = ['res.partner', 'l10n.country.filter.mixin'] # Mandatory Mixin

    @api.model
    def _get_view(self, view_id=None, view_type='form', **options):
        # 1. Get the standard view architecture
        arch, view = super()._get_view(view_id, view_type, **options)

        # 2. Define the country (Peru) where fields SHOULD be visible
        peru = self.env.ref('base.pe', raise_if_not_found=False)
        if not peru:
            return arch, view

        # 3. Apply the filter
        # If the current company's country is NOT in the allowed list (Peru),
        # the specified tags will be hidden.
        arch, view = self._tags_invisible_per_country(
            arch, view, view_type,
            tags=[
                'l10n_pe_vat_code',              # Field Name
                ('group', 'l10n_pe_group_vat')   # specific XML group
            ],
            countries=[peru] # List of countries where fields are VISIBLE
        )
        return arch, view
                            

3. Critical Considerations

Scenario	Action	Expected Result
1. Cross-Company Context	Log in as a user with access to both Company A (Peru) and Company B (USA). Open a Partner form in Company A. Then switch to Company B.	Fields restricted to Peru (e.g., VAT Code) must be visible in Company A and hidden immediately upon switching to Company B.
2. List (Tree) View Integrity	Navigate to the Partner List view in a restricted company (e.g., USA).	The column header for the restricted field must not appear. Odoo 19's column_invisible should prevent blank columns.
3. Cache Reliability	Switch companies rapidly (A -> B -> A) and reload the page between switches.	The correct visibility state must persist reliably. No "leaking" of fields from one company to another due to browser or server-side caching.