I try to add a field in treeview account_invoice_line in invoice which compute and display VAT price per account_invoice_line (1). It's done but when try to recompute total tax (2), the VAT price per line is recompute to 0 (Except for line create in sale.order)

Have you an idea for VAT prices are good for all account.invoice.line 

My code : 

class cap_account_invoice_line(osv.osv):

_inherit = 'account.invoice.line'

_columns = {

'price_with_tax':fields.float(string='Prix TTC', store=True, readonly=True,),

}

@api.multi

def product_id_change(self, product, account_id, uom_id, qty=0, name='', type_x='out_invoice',

partner_id=False, fposition_id=False, price_unit=False, currency_id=False, company_id=None,context = None):

if context is None:

context = {}

if partner_id:

res = super(cap_account_invoice_line, self).product_id_change(product, uom_id, qty=qty, name=name, type=type_x,

partner_id=partner_id, fposition_id=fposition_id, price_unit=price_unit, currency_id=currency_id,

company_id=company_id)

if res == 0:

return res

context = self._context

company_id = company_id if company_id is not None else context.get('company_id', False)

self = self.with_context(company_id=company_id, force_company=company_id)

part = self.env['res.partner'].browse(partner_id)

product = self.env['product.product'].browse(product)

fpos = self.env['account.fiscal.position'].browse(fposition_id)

if type in ('out_invoice', 'out_refund'):

account = product.property_account_income or product.categ_id.property_account_income_categ

else:

account = product.property_account_expense or product.categ_id.property_account_expense_categ

account = fpos.map_account(account)

if type in ('out_invoice', 'out_refund'):

taxes = product.taxes_id or account.tax_ids

else:

taxes = product.supplier_taxes_id or account.tax_ids

taxes = fpos.map_tax(taxes)

taxes.ids

values = res['value']

price = values.get('price_unit', 0) * (1 - values.get('discount', 0) / 100.0)

taxes = values.get('invoice_line_tax_id')

taxes = self.env['account.tax'].browse(taxes)

tax_res = taxes.compute_all(price, qty,product=product, partner=part)

values['price_with_tax'] = tax_res['total_included']

res['value'] = values

return res

@api.multi

def uos_id_change(self, product, uom, qty=0, name='', type_x='out_invoice', partner_id=False,

fposition_id=False, price_unit=False, currency_id=False, company_id=None):

if uom:

super(cap_account_invoice_line, self).uos_id_change(product, uom, qty, name, type_x, partner_id, fposition_id, price_unit, currency_id, company_id)