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hey ! here is my code please tell me how can i solve the problem

model file :

from datetime import datetime
from odoo import api, fields, models, _
from odoo.exceptions import ValidationError

class EbmManagement(models.Model):
_name = "ebm.management"
_inherit = ['mail.thread', 'mail.activity.mixin']
_description = "EBM Management"

@api.depends('pre_costing_line_ids', 'pre_costing_line_ids.amount')
def compute_total_pre_costing_amount(self):
for rec in self:
total = 0
for line in rec.pre_costing_line_ids:
total += line.amount
rec['total_pre_costing_amount'] = total

@api.depends('entertainment_expense_line_ids', 'entertainment_expense_line_ids.entertainment_bill_amount')
def compute_entertainment_total(self):
for rec in self:
total = 0
for line in rec.entertainment_expense_line_ids:
total += line.entertainment_bill_amount
rec['entertainment_total'] = total

@api.depends('conveyance_expense_line_ids', 'conveyance_expense_line_ids.conveyance_bill_amount')
def compute_conveyance_total(self):
for rec in self:
total = 0
for line in rec.conveyance_expense_line_ids:
total += line.conveyance_bill_amount
rec['conveyance_total'] = total

@api.depends('miscellaneous_expense_line_ids', 'miscellaneous_expense_line_ids.miscellaneous_bill_amount')
def compute_miscellaneous_total(self):
for rec in self:
total = 0
for line in rec.miscellaneous_expense_line_ids:
total += line.miscellaneous_bill_amount
rec['miscellaneous_total'] = total

@api.depends('entertainment_total', 'conveyance_total', 'miscellaneous_total')
def compute_total_bill_amount(self):
for rec in self:
rec.total_billing_amount = rec.entertainment_total + rec.conveyance_total + rec.miscellaneous_total

ebm_no = fields.Char(string='EBM No :', required=True, copy=False, readonly=True, default=lambda
self: _('New')) # sequence_id
name = fields.Many2one('hr.employee', string='Created By :', default=lambda self: self.env.user.employee_id,
readonly=True)
dept = fields.Many2one('hr.department', string='Department :', default=lambda self: self.env.user.department_id,
readonly=True)
expense_dept_for = fields.Selection([
('own', 'Own'),
('other', 'Other'),
], string='Expense For :', required=True, default='own', tracking=True)
employee_id = fields.Many2one('hr.employee', string='Employee :', tracking=True)
expense_dept = fields.Char(string='Exp Department :')
ebm_date = fields.Datetime(string='EBM Create Date :', default=datetime.today(), readonly=True)
required_date = fields.Date(string='Required Date :', required=True, tracking=True)

reference = fields.Char(string='Reference :', required=True, tracking=True)
purpose = fields.Text(string='Purpose :', required=True, tracking=True)
state = fields.Selection([('draft', 'Draft'), ('department manager', 'Department Manager'), ('audit', 'Audit'),
('account', 'Account'), ('management', 'Management')], default='draft', string="Status",
tracking=True)

# Notebook Line Added field for pre-costing
pre_costing_line_ids = fields.One2many('pre_costing.lines', 'pre_costing_id', string='Pre-costing Line')
# Notebook Line Added field for entertainment
entertainment_expense_line_ids = fields.One2many('entertainment.expense.lines', 'EEL_id',
string='Entertainment Line')
# Notebook Line Added field for conveyance
conveyance_expense_line_ids = fields.One2many('conveyance.expense.lines', 'CEL_id', string='Conveyance Line')
# Notebook Line Added field for miscellaneous
miscellaneous_expense_line_ids = fields.One2many('miscellaneous.expense.lines', 'MEL_id', string='Miscellaneous '
'Line')
#################### Computed Field ##################
total_pre_costing_amount = fields.Float(compute='compute_total_pre_costing_amount', store=True,
string='Total Pre-Costing '
'Amount ')

entertainment_total = fields.Float(string='Entertainment Total',
compute='compute_entertainment_total', store=True)
conveyance_total = fields.Float(string='Conveyance Total',
compute='compute_conveyance_total', store=True)
miscellaneous_total = fields.Float(string='Miscellaneous Total', store=True,
compute='compute_miscellaneous_total')
total_billing_amount = fields.Float(string='Total Bill Amount', store=True,
compute='compute_total_bill_amount')

def action_department(self):
for rec in self:
rec.state = 'department manager'

def action_audit(self):
for rec in self:
rec.state = 'audit'

def action_account(self):
for rec in self:
rec.state = 'account'

def action_draft(self):
for rec in self:
rec.state = 'draft'

def action_management(self):
for rec in self:
rec.state = 'management'

# sequence value
@api.model
def create(self, vals):
if vals.get('ebm_no', _('New')) == _('New'):
vals['ebm_no'] = self.env['ir.sequence'].next_by_code('ebm.management') or _(
'New') # sequence value
res = super(EbmManagement, self).create(vals)
return res

# field validation
@api.constrains('requested_amount')
def check_requested_amount(self):
for rec in self:
if rec.requested_amount == 0:
raise ValidationError(
_("Please Enter Correct Amount. Amount can not be Zero !!\n ---- দয়া করে সঠিক পরিমাণ লিখুন "
"----!"))

# Date field validation
@api.constrains('required_date')
def _check_required_date(self):
for rec in self:
if rec.required_date < fields.Date.today():
raise ValidationError("The Required date cannot be set in the past !!\n --- প্রয়োজনীয় তারিখ অতীতে "
"সেট "
"করা যাবে না ---|")

# Get automatic department after selecting employee
@api.onchange('employee_id')
def onchange_employee_id(self):
if self.employee_id:
if self.employee_id.department_id.name:
self.expense_dept = self.employee_id.department_id.name
else:
self.expense_dept = ''

# Notebook model for pre-costing
class PreCostingLines(models.Model):
_name = "pre_costing.lines"
_description = "Pre-Costing Lines"

pre_costing_id = fields.Many2one('ebm.management', string='pre_costing')
name = fields.Char(string='Description', required=True)
display_type = fields.Selection([
('line_section', "Section"),
('line_note', "Note")], default=False, help="Technical field for UX purpose.")
amount = fields.Integer(string='Amount')

# Notebook model for Entertainment
class EntertainmentExpenseLines(models.Model):
_name = "entertainment.expense.lines"
_description = "Entertainment Expense Lines"

# Computed function
@api.depends('req_qty', 'unit_cost')
def _get_entertainment_bill_amount(self):
for rec in self:
rec.entertainment_bill_amount = rec.req_qty * rec.unit_cost

EEL_id = fields.Many2one('ebm.management', string='EEL')
product_id = fields.Many2one('ebm.product', string='Product', domain=[('is_entertainment', '=', True)],
change_default=True, required=True) # Category based product
req_qty = fields.Integer(string="Quantity ", required=True)
unit_cost = fields.Float(string="Unit Price")
entertainment_bill_amount = fields.Float(string='Bill Amount', compute='_get_entertainment_bill_amount', store=True)

# Get unit cost of any product after selecting the product
@api.onchange('product_id')
def onchange_product_id(self):
if self.product_id:
if self.product_id.unit_cost:
self.unit_cost = self.product_id.unit_cost
else:
self.unit_cost = ''

# Notebook model for Conveyance
class ConveyanceExpenseLines(models.Model):
_name = "conveyance.expense.lines"
_description = "Conveyance Expense Lines"

CEL_id = fields.Many2one('ebm.management', string='CEL')
product_id = fields.Many2one('ebm.product', string='Product', domain=[('is_conveyance', '=', True)],
change_default=True, required=True)
con_from = fields.Char(string="From", required=True)
con_to = fields.Char(string="Destination", required=True)
conveyance_bill_amount = fields.Float(string='Bill Amount')

# Notebook model for Miscellaneous
class MiscellaneousExpenseLines(models.Model):
_name = "miscellaneous.expense.lines"
_description = "Miscellaneous Expense Lines"

MEL_id = fields.Many2one('ebm.management', string='CEL')
product_id = fields.Many2one('ebm.product', string='Product', domain=[('is_miscellaneous', '=',
True)],
change_default=True, required=True)
name = fields.Char(string='Name')
designation = fields.Char(string='Designation', required=True)
dept = fields.Char(string='Department')
dist = fields.Char(string='Home District')
phone = fields.Char(string='Phone No')
payment_date = fields.Date(string='Payment Date', required=True)
work_place = fields.Char(string='Place of Work')
miscellaneous_bill_amount = fields.Float(string='Bill Amount')
purpose = fields.Text(string='Purpose')
remark = fields.Char(string='Remarks')

@api.constrains('payment_date')
def _check_payment_date(self):
for rec in self:
if rec.payment_date < fields.Date.today():
raise ValidationError("The Payment date cannot be set in the past !!\n --- প্রয়োজনীয় তারিখ অতীতে "
"সেট "
"করা যাবে না ---|")

view file :
<?xml version="1.0" encoding="utf-8"?>
<odoo>
<!-- Action view -->

<record id="action_ebm_management" model="ir.actions.act_window">
<field name="name">EBM</field>
<field name="type">ir.actions.act_window</field>
<field name="res_model">ebm.management</field>
<field name="view_mode">tree,form</field>
<field name="help" type="html">
<p class="o_view_nocontent_smiling_face">
Create Your New EBM Record !!!
</p>
</field>
</record>

<!-- from view -->

<record id="view_ebm_form" model="ir.ui.view">
<field name="name">ebm.management.form</field>
<field name="model">ebm.management</field>
<field name="arch" type="xml">
<form>
<header>
<button id="button_department" name="action_department" string="Department Manager Approve"
class="btn-primary"
states="draft" type="object"/>
<button id="button_audit" name="action_audit" string="Audit Approve" class="btn-primary"
states="department manager" type="object"/>
<button id="button_account" name="action_account" string="Account Approve" class="btn-primary"
states="audit" type="object"/>
<button id="button_draft" name="action_draft" string="Set To Draft" class="btn-primary"
states="management" type="object"/>
<button id="button_management" name="action_management" string="Management Approve"
class="btn-primary"
states="account" type="object"/>
<field name="state" widget="statusbar"
statusbar_visible="draft,department manager,audit,account,management"/>
</header>
<sheet>
<!-- For Sequence Id-->
<div class="oe_title">
<h3>
<field name="ebm_no" readonly="1"/>
</h3>
</div>
<!-- End -->
<group>
<group>
<field name="name" readonly="1"/>
<field name="dept" readonly="1"/>
<field name="expense_dept_for"/>
<field name="employee_id" attrs="{'invisible':[('expense_dept_for','=','own')]}"/>
<field name="expense_dept" attrs="{'invisible':[('expense_dept_for','=','own')]}"/>
</group>
<group>
<field name="ebm_date"/>
<field name="required_date"/>
<field name="reference"/>
<field name="purpose"/>
</group>
</group>

<!-- Bottom part in Notebook -->
<h3>Pre-costing</h3>
<notebook>
<page string="Pre-costing" name="pre_costing_line">
<field name="pre_costing_line_ids" widget="section_and_note_one2many">
<tree editable="bottom">
<control>
<create name="add_line_control" string="Add a Product"/>
<create name="add_section_control" string="Add a section"
context="{'default_display_type': 'line_section'}"/>
</control>
<field name="name" widget="section_and_note_text"/>
<field name="display_type" invisible="1"/>
<field name="amount"/>
</tree>
<form>
<group>
<group>
<field name="name"/>
</group>
<group>
<field name="amount"/>
</group>
</group>
</form>
</field>
<group class="oe_subtotal_footer">
<field name="total_pre_costing_amount" class="oe_subtotal_footer_separator"/>
</group>
</page>
</notebook>
<h3>Billing</h3>
<notebook>
<page string="Entertainment" name="entertainment_expense">
<field name="entertainment_expense_line_ids">
<tree editable="bottom">
<field name="product_id"/>
<field name="req_qty" optional="show"/>
<field name="unit_cost" optional="show"/>
<field name="entertainment_bill_amount" optional="show"/>
</tree>
<form>
<group>
<group>
<group>
<field name="product_id"/>
</group>
<group>
<field name="req_qty"/>
</group>
<group>
<field name="unit_cost"/>
</group>
<group>
<field name="entertainment_bill_amount"/>
</group>
</group>
</group>
</form>
</field>
</page>

<page string="Conveyance" name="conveyance_expense">
<field name="conveyance_expense_line_ids">
<tree editable="bottom">
<field name="product_id"/>
<field name="con_from" optional="show"/>
<field name="con_to" optional="show"/>
<field name="conveyance_bill_amount" optional="show"/>
</tree>
<form>
<group>
<group>
<field name="product_id"/>
</group>
<group>
<field name="con_from"/>
</group>
<group>
<field name="con_to"/>
</group>
<group>
<field name="conveyance_bill_amount"/>
</group>
</group>
</form>
</field>
</page>
<page string="Miscellaneous" name="miscellaneous_expenses">
<field name="miscellaneous_expense_line_ids">
<tree editable="bottom">
<field name="product_id"/>
<field name="name" optional="show"/>
<field name="dept" optional="show"/>
<field name="designation" optional="show"/>
<field name="dist" optional="show"/>
<field name="phone" optional="show"/>
<field name="payment_date" optional="show"/>
<field name="work_place" optional="show"/>
<field name="miscellaneous_bill_amount" optional="show"/>
<field name="purpose" optional="show"/>
<field name="remark" optional="show"/>
</tree>
<form>
<group>
<group>
<field name="product_id"/>
</group>
<group>
<field name="name"/>
</group>
<group>
<field name="dept"/>
</group>
<group>
<field name="designation"/>
</group>
<group>
<field name="dist"/>
</group>
<group>
<field name="phone"/>
</group>
<group>
<field name="payment_date"/>
</group>
<group>
<field name="work_place"/>
</group>
<group>
<field name="miscellaneous_bill_amount"/>
</group>
<group>
<field name="purpose"/>
</group>
<group>
<field name="remark"/>
</group>
</group>
</form>
</field>
</page>

</notebook>
<!--Notebook End-->
<group class="oe_subtotal_footer">
<field name="entertainment_total"/>
<field name="conveyance_total"/>
<field name="miscellaneous_total"/>
<field name="total_billing_amount" class="oe_subtotal_footer_separator"/>
</group>
</sheet>
<div class="oe_chatter">
<field name="message_follower_ids"/>
<field name="activity_ids"/>
<field name="message_ids"/>
</div>
</form>
</field>
</record>

<!-- Tree view-->

<record id="view_ebm_tree" model="ir.ui.view">
<field name="name">ebm.management.tree</field>
<field name="model">ebm.management</field>
<field name="arch" type="xml">
<tree sample="1" multi_edit="1">
<field name="ebm_no"/>
<field name="name" optional="show"/>
<field name="dept" optional="show"/>
<field name="employee_id" optional="show"/>
<field name="expense_dept" optional="show"/>
<field name="ebm_date" optional="show"/>
<field name="required_date" optional="show"/>
<field name="expense_dept_for" optional="show"/>
<field name="reference" optional="show"/>
<field name="purpose" optional="show"/>
</tree>
</field>
</record>
</odoo>