Hello,
I am new in odoo. I wanted to generate a report - an excel format. I am looking for a python approach example for these sample data.

This my xml for the qweb in my pdf format:

<tbody class="table_data">
											<t t-set="pickings" t-value="o.get_pickings(date_start, date_end)" />
											<t t-foreach="pickings" t-as="pick">
												<t t-set="line_items" t-value="o.get_line_items(pick)"/>
											    <t t-foreach="line_items" t-as="line">
											        <tr>
											        	<td><span t-esc="i"/><t t-set="i" t-value="i+1"/></td>
											            <td><span t-esc="line.get('partner_name')" /></td>
											            <td><span t-esc="line.get('si_number')" /></td>
											            <td><span t-esc="line.get('product_name')" /></td>
											            <td><span t-esc="line.get('done_qty')" /></td>
											            <t t-set="qty" t-value="qty + line.get('done_qty')"/>
											        </tr>
											    </t>
											</t>
											<tr class="total">
												<td colspan="3"></td>
												<td><span>Total:</span></td>
												<td><span t-esc="qty" /></td>
											</tr>
										</tbody>

I tried to display this in excel but got error.

the items:

    @api.multi
    def get_line_items(self, picking_id):
        line_items = picking_id.pack_operation_ids
        items = []
        for item in line_items:
            items.append({"product_name": item.product_id.name, "done_qty": item.qty_done, 
                          "si_number": " ".join([ invoice.name for invoice in picking_id.sale_id.invoice_ids]),
                          "partner_name": picking_id.partner_id.name })
        
        
        return items

for excel:

        sheet.write(0, 1, "REPORT", header_title)    
        sheet.write(4, 0, "CUSTOMER NAME")
        sheet.write(4, 1, "I.S. #")
        sheet.write(4, 2, "PRODUCT NAME")
        sheet.write(4, 3, "NO. OF BAGS")
               
        get_line_items = self.get_line_items(picking_id)     
                
        for i in get_line_items:
            print("get_line_items",i)      

error:

get_line_items = self.get_line_items(picking_id)
NameError: global name 'picking_id' is not defined