Hi,

You can click following button for creating reports in odoo 12  Qweb reports in odoo 12

Thanks for your answers. 

I had a look at the manual. This specific manual is for changing an existing report. My aim is to add a new report. 

Nevertheless I inherited the account.invoice module in my module in the following way: 

from openerp import models, fields, api
 class custom_vierimpott(models.Model):
     _name = 'custom_module.custom_module'
  _inherit="account.invoice"
     name = fields.Char()

Furthermore I wrote in my report.xml:

<openerp>
    <data>
        <report 
            id="custom_report_without_prices"
            model="account.invoice"
            string="Invoice without prices"
            report_type="qweb-pdf"
            name="custom_module.report_without_prices"
            attachment_use="False"
            file="custom_module.custom_module"
        />
    </data>
</openerp>

After this I refreshed the module. Unfortuneatly there were no results. That means under Invoicing I can only print the default invoice-report.

What is wrong in my approach?