[FIX] contract: multi-company assignment notification

Steps to reproduce the problem:

1. Log in as Mitchell Admin.
2. Create contract CNT-A for company CMP-A, assigned to Marc Demo.
3. Create contract CNT-B for company CMP-B, assigned to Marc Demo.
4. Run cron to create recurring invoices.

Actual results:

- Odoo sends automated assignment emails to Marc Demo, which indicate the name of the company activated for `__system__` user whlie the cron was being executed.

Expected results after this patch:

- Odoo sends automated assignment emails to Marc Demo, which indicate the invoice company.

@Tecnativa TT24657

contract/README.rst

@@ -74,6 +74,7 @@ Known issues / Roadmap
 ======================
 
 * Recover states and others functional fields in Contracts.
+* Remove ``models/ir_ui_view.py`` in v13, where the workaround it contains is supported upstream.
 
 Bug Tracker
 ===========

contract/models/__init__.py

@@ -13,3 +13,4 @@ from . import contract_tag
 from . import res_company
 from . import res_config_settings
 from . import contract_terminate_reason
+from . import ir_ui_view

contract/models/contract.py

@@ -546,8 +546,15 @@ class ContractContract(models.Model):
         if not date_ref:
             date_ref = fields.Date.context_today(self)
         domain = self._get_contracts_to_invoice_domain(date_ref)
-        contracts_to_invoice = self.search(domain)
-        return contracts_to_invoice._recurring_create_invoice(date_ref)
+        invoices = self.env["account.invoice"]
+        # Invoice by companies, so assignation emails get correct context
+        companies_to_invoice = self.read_group(domain, ["company_id"], ["company_id"])
+        for row in companies_to_invoice:
+            contracts_to_invoice = self.search(row["__domain"]).with_context(
+                allowed_company_ids=[row["company_id"][0]]
+            )
+            invoices |= contracts_to_invoice._recurring_create_invoice(date_ref)
+        return invoices
 
     @api.multi
     def action_terminate_contract(self):

contract/models/ir_ui_view.py

@@ -0,0 +1,19 @@
+# Copyright 2020 Tecnativa - Jairo Llopis
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+
+from odoo import api, models
+
+
+class IrUiView(models.Model):
+    _inherit = "ir.ui.view"
+
+    @api.model
+    def _prepare_qcontext(self):
+        """Patch context to use fw-compatible v13 company."""
+        # TODO Delete this method in v13; it's upstream there
+        result = super()._prepare_qcontext()
+        if self.env.context.get("allowed_company_ids"):
+            result["res_company"] = self.env["res.company"].browse(
+                self.env.context["allowed_company_ids"][0]
+            ).sudo()
+        return result

contract/readme/ROADMAP.rst

@@ -1 +1,2 @@
 * Recover states and others functional fields in Contracts.
+* Remove ``models/ir_ui_view.py`` in v13, where the workaround it contains is supported upstream.

contract/static/description/index.html

@@ -425,6 +425,7 @@ To use it, just select the template on the contract and fields will be filled au
 <h1><a class="toc-backref" href="#id3">Known issues / Roadmap</a></h1>
 <ul class="simple">
 <li>Recover states and others functional fields in Contracts.</li>
+<li>Remove <tt class="docutils literal">models/ir_ui_view.py</tt> in v13, where the workaround it contains is supported upstream.</li>
 </ul>
 </div>
 <div class="section" id="bug-tracker">