Usage

An example of CSV report for partners on a module called module_name:

A python class

from odoo import models

class PartnerCSV(models.AbstractModel):
    _name = 'report.base_report_csv.partner_csv'
    _inherit = 'report.base_report_csv.abstract'

    def generate_csv_report(self, writer, data, partners):
        writer.writeheader()
        for obj in partners:
            writer.writerow({
                'name': obj.name,
                'email': obj.email,
            })

    def csv_report_options(self):
        res = super().csv_report_options()
        res['fieldnames'].append('name')
        res['fieldnames'].append('email')
        res['delimiter'] = ';'
        res['quoting'] = csv.QUOTE_ALL
        return res

A report XML record

<report
    id="partner_csv"
    model="res.partner"
    string="Print to CSV"
    report_type="csv"
    name="module_name.report_name"
    file="res_partner"
    attachment_use="False"
/>