Hi Feryial,

You can easily handle this one with a access rule definition,

So this example is based on your explanation:

1- Inherit res.users to compute on the fly groups

class ResUsers(models.Model):
    _inherit = 'res.users'

    user_group = fields.Many2one('res.groups',compute='_compute_user_group')

    def _compute_user_group(self):
        for user in self:
            if self.env.user.has_group('my_module.group_a'):
                user.user_group = self.env('res.groups').search([('name','=','Group A')])
            else:
                user.user_group = self.env('res.groups').search([('name','=','Group B')])

2- Define the rule;

record model="ir.rule" id="my_module_record_based_rule">
    field name="name">Users can only see their records
    field name="model_id" ref="model_example_form"/>
    field eval="1" name="perm_unlink"/>
    field eval="1" name="perm_write"/>
    field eval="1" name="perm_read"/>
    field eval="1" name="perm_create"/>
    field name="domain_force">[('access_groups', '=',user.user_group.id)]
    field name="groups"
           eval="[(6, 0,  [ref('proc_pre_request.group_ppr_user')])]"/>
record>