Thanks for your feedback still getting error, can you please make above suggested change to below model and resend the code. 

class FoodBookingLine(models.Model):

    """Model that handles the food booking"""

    _name = "food.booking.line"

    _description = "Hotel Food Line"

    _rec_name = 'food_id'

    @tools.ormcache()

    def _get_default_uom_id(self):

        """Method for getting the default uom id"""

        return self.env.ref('uom.product_uom_unit')

    booking_id = fields.Many2one("room.booking", string="Booking",

                                 help="Shows the room Booking",

                                 ondelete="cascade")

    food_id = fields.Many2one('lunch.product', string="Product",

                              help="Indicates the Food Product")

    description = fields.Char(string='Description',

                              help="Description of Food Product",

                              related='food_id.display_name')

    uom_qty = fields.Float(string="Qty", default=1,

                           help="The quantity converted into the UoM used by "

                                "the product")

    uom_id = fields.Many2one('uom.uom', readonly=True,

                             string="Unit of Measure",

                             default=_get_default_uom_id, help="This will set "

                                                               "the unit of"

                                                               " measure used")

    price_unit = fields.Float(related='food_id.price', string='Price',

                              digits='Product Price',

                              help="The price of the selected food item.")

    tax_ids = fields.Many2many('account.tax',

                               'hotel_food_order_line_taxes_rel',

                               'food_id', 'tax_id',

                               string='Taxes',

                               help="Default taxes used when selling the food"

                                    " products.",

                               domain=[('type_tax_use', '=', 'sale')])

    currency_id = fields.Many2one(related='booking_id.pricelist_id.currency_id'

                                  , string="Currency",

                                  help='The currency used')

    price_subtotal = fields.Float(string="Subtotal",

                                  compute='_compute_price_subtotal',

                                  help="Total Price Excluding Tax",

                                  store=True)

    price_tax = fields.Float(string="Total Tax",

                             compute='_compute_price_subtotal',

                             help="Tax Amount",

                             store=True)

    price_total = fields.Float(string="Total",

                               compute='_compute_price_subtotal',

                               help="Total Price Including Tax",

                               store=True)

    state = fields.Selection(related='booking_id.state',

                             string="Order Status",

                             help=" Status of the Order",

                             copy=False)

    @api.depends('uom_qty', 'price_unit', 'tax_ids')

    def _compute_price_subtotal(self):

        """Compute the amounts of the room booking line."""

        for line in self:  

            base_line = line._prepare_base_line_for_taxes_computation()

            self.env['account.tax']._add_tax_details_in_base_line(base_line, self.env.company)

            line.price_subtotal = base_line['tax_details']['total_excluded_currency']

            line.price_total = base_line['tax_details']['total_included_currency']

            line.price_tax = line.price_total - line.price_subtotal

            if self.env.context.get('import_file',

                                    False) and not self.env.user. \

                    user_has_groups('account.group_account_manager'):

                line.tax_id.invalidate_recordset(

                    ['invoice_repartition_line_ids'])

    def _prepare_base_line_for_taxes_computation(self):

        """ Convert the current record to a dictionary in order to use the generic taxes computation method

        defined on account.tax.

        :return: A python dictionary.

        """

        self.ensure_one()

        return self.env['account.tax']._prepare_base_line_for_taxes_computation(

            self,

            **{

                'tax_ids': self.tax_ids,

                'quantity': self.uom_qty,

                'partner_id': self.booking_id.partner_id,

                'currency_id': self.currency_id,

            },

        )

    def search_food_orders(self):

        """Returns list of food orders"""

        return (self.search([]).filtered(lambda r: r.booking_id.state not in [

            'check_out', 'cancel', 'done']).ids)

Hi,

The error occurs when adding a service line such as Food. Odoo raises a KeyError: 'total_excluded_currency' because the compute method in your custom food_booking_line model expects the keys total_excluded_currency and total_included_currency in the tax details dictionary, but these keys are not always present.

The root cause is that Odoo’s tax computation API normally returns total_excluded and total_included. The _currency versions of those keys are only provided if a currency is explicitly passed to _add_tax_details_in_base_line. In your module, the logic was adapted from account.move.line but the necessary currency argument was not included, which is why the expected keys are missing.

To fix this, you have a few options. The simplest is to switch your code to use total_excluded and total_included instead of the _currency versions. Alternatively, you can pass currency=line.currency_id to _add_tax_details_in_base_line, which will ensure that the _currency keys are added to the dictionary. A safer approach is to use .get() with fallback values so your code works whether or not those keys are present.

In short, adjusting your _compute_price_subtotal method to either use the correct keys, pass the currency, or handle both cases defensively will resolve the error.

Hope it helps