Step1: Created module with scaffold command.

Step2: model.py

# -*- coding: utf-8 -*-
from odoo import models, fields, api
from openerp import models, api _
from openerp.tools import amount_to_text_en
from openerp import tools
from openerp.tools.amount_to_text import amount_to_text

 class purchase_agreement_updates(models.Model):
     _name = 'purchase_agreement_updates.purchase_agreement_updates'
     _inherit = 'self.header'

     @api.multi
     def amount_to_text(self, amount, currency='Euro'):
         return amount_to_text(amount, currency)
purchase_agreement_updates()
class purchase_requisition(models.Model):
    _inherit = 'purchase.requisition'

     @api.multi
     def amount_to_text(self, amount, currency='Euro'):
         return amount_to_text(amount, currency)

templates.xml:

        <t t-name="purchase_requisition.report_purchaserequisitions">
            <t t-call="report.html_container">
                <t t-foreach="docs" t-as="o">
                    <!--<t t-call="report.external_layout">-->
                        <div class="header">


                              <div style="float:left;width:100px;"></div>
                              <div style="margin:0 auto;width:100%;">
                                  <h3 style="text-align:center;text-decoration: underline;margin-top:50px;">PURCHASE REQUISITION</h3></div>
                              <div style="float:right;width:100px;">
                                  <img t-if="res_company.logo" t-att-src="'data:image/png;base64,%s' %res_company.logo" height="120px" width="100px"/></div>

                            <!--<t t-esc="o.name"/>-->
                        </div>
.
.
.
.
.
.
               <tr t-foreach="o.line_ids" t-as="line_ids">
                                    <t t-set="total_value" t-value="total_value+line_ids.product_qty * line_ids.price_unit"/>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"><span t-esc="line_ids_index+1"/> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"><span t-field="line_ids.product_id.name"/></td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"><span t-field="line_ids.product_qty"/> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"><span t-field="line_ids.price_unit"/> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"><span t-esc="line_ids.product_qty * line_ids.price_unit"/> </td></tr>

                                <tr><td style="border:1px solid #000;padding-left:5px;height:25px;"> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"> </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;">Total </td>
                                    <td style="border:1px solid #000;padding-left:5px;height:25px;"> <t t-esc="total_value"/></td></tr>


                                <tr><td style="border:1px solid #000;padding-left:5px;height:25px;" colspan="5"><span style="font-weight:bold;">TOTAL PURCHASE:</span> <t t-esc="total_value"/> </td></tr>
                                <tr><td style="border:1px solid #000;padding-left:5px;height:25px;" colspan="5"><span style="font-weight:bold;">TOTAL PURCHASE IN WORDS:</span> <span t-esc="o.amount_to_text(total_value, 'Aed')"/>
                                        <!--<span t-esc="o.amount_to_text('2000', o.currency_id)"/>-->  </td></tr>

Error: Error to render compiling AST AttributeError: 'purchase.requisition' object has no attribute 'amount_to_text' Template: 844 Path: /templates/t/t/t/t/div[2]/table[2]/tr[5]/td/span[2] Node: