I am adding some custom data to the web session. Like this: 

from odoo import models
from odoo.http import request

class IrHttp(models.AbstractModel):
    _inherit = 'ir.http'
    def session_info(self):
        result = super(IrHttp, self).session_info()
        result['key1'] = get_value_1()
        result['key2'] = get_value_2()
        return result

def get_value_1():      ( same for get_value_2() )
    return self.env['*model*'].browse(*id*).*attribute*

I will retrieve my data with:

     var session = require('web.session');
     console.log(session);

This works perfectly fine in the backend, but not in the frontend (the actual website)
The log shows me that the custom keys are missing in the frontend. What is the reason for this, and how do I solve it? 
 
There is no error being logged.