[IMP] project: default company of a task

In Project app, we now ensure the company of a task. Indeed, since that
model can be billed, and is important in some business, we need to ensure
its link to a company. A task can live outside a project, so the company
of a task can not be related. Task company can be set by user, but must
be the same as the project (is set), as the task can be billed depending
on project properties.

Task-1999686

addons/project/models/project.py

@@ -454,6 +454,12 @@ class Task(models.Model):
             return False
         return self.stage_find(project_id, [('fold', '=', False)])
 
+    @api.model
+    def _default_company_id(self):
+        if self._context.get('default_project_id'):
+            return self.env['project.project'].browse(self._context['default_project_id']).company_id
+        return self.env.company
+
     @api.model
     def _read_group_stage_ids(self, stages, domain, order):
         search_domain = [('id', 'in', stages.ids)]
@@ -508,7 +514,7 @@ class Task(models.Model):
         default=lambda self: self._get_default_partner(),
         domain="['|', ('company_id', '=', False), ('company_id', '=', company_id)]")
     manager_id = fields.Many2one('res.users', string='Project Manager', related='project_id.user_id', readonly=True, related_sudo=False)
-    company_id = fields.Many2one('res.company', string='Company', required=True, default=lambda self: self.env.company)
+    company_id = fields.Many2one('res.company', string='Company', required=True, default=_default_company_id)
     color = fields.Integer(string='Color Index')
     user_email = fields.Char(related='user_id.email', string='User Email', readonly=True, related_sudo=False)
     attachment_ids = fields.One2many('ir.attachment', compute='_compute_attachment_ids', string="Main Attachments",
@@ -616,6 +622,8 @@ class Task(models.Model):
                 self.partner_id = self.project_id.partner_id
             if self.project_id not in self.stage_id.project_ids:
                 self.stage_id = self.stage_find(self.project_id.id, [('fold', '=', False)])
+            # keep multi company consistency
+            self.company_id = self.project_id.company_id
         else:
             self.stage_id = False
 
@@ -625,6 +633,13 @@ class Task(models.Model):
             if task.parent_id and task.child_ids:
                 raise ValidationError(_('Task %s cannot have several subtask levels.' % (task.name,)))
 
+    @api.constrains('company_id', 'project_id')
+    def _check_multi_company(self):
+        for task in self:
+            if task.project_id:
+                if task.project_id.company_id != task.company_id:
+                    raise ValidationError(_('Your task must beo in the same company as its project.'))
+
     @api.returns('self', lambda value: value.id)
     def copy(self, default=None):
         if default is None:

addons/sale_timesheet/models/project.py

@@ -183,7 +183,8 @@ class ProjectTask(models.Model):
     @api.onchange('project_id')
     def _onchange_project(self):
         result = super(ProjectTask, self)._onchange_project()
-        self.sale_line_id = self.project_id.sale_line_id
+        if self.project_id.sale_line_id:
+            self.sale_line_id = self.project_id.sale_line_id
         if not self.parent_id and not self.partner_id:
             self.partner_id = self.sale_line_id.order_partner_id
         # set domain on SO: on non billable project, all SOL of customer, otherwise the one from the SO