Hi, this is exactly what you need: https://youtu.be/An6YTH3kJD8

Thanks

Answer of Mily Shajan works ! saved my day, thanks

Hi

In xml, you can have this code. Here we are inheriting the signup page template and add the field

<?xml version="1.0" encoding="utf-8"?>
<!--Add an input field in sign up page, to have the gender-->
<odoo>
<template id="signup_add_gender" inherit_id="auth_signup.signup">
        <xpath expr="//input[@name='token']" position="before">
            <div class="mb-3">
                <label for="sex">Sex</label>
                <select name="gender" class="form-control link-style">
                    <option value="">--select--</option>
                    <option value="male">Male</option>
                    <option value="female">Female</option>
<option value="transgender">Transgender</option>
                </select>
            </div>
        </xpath>
    </template>
</odoo>

In controllers, by overwriting the function 'web_auth_signup' like this, and we can update the qcontext with gender,  later we can have the value

import werkzeug
from werkzeug.urls import url_encode
from odoo import _
from odoo.addons.auth_signup.controllers.main import AuthSignupHome
from odoo.addons.auth_signup.models.res_users import SignupError
from odoo.exceptions import UserError
from odoo.http import _logger, request


class WebsiteLogin(AuthSignupHome):
def web_auth_signup(self, *args, **kw):
    """Overwrite the function web_auth_signup, to add the value of gender
    to qcontext"""
    qcontext = self.get_auth_signup_qcontext()
    qcontext.update({
        'gender': kw.get('gender')
    })
      if not qcontext.get('token') and not qcontext.get('signup_enabled'):
        raise werkzeug.exceptions.NotFound()
    if 'error' not in qcontext and request.httprequest.method == 'POST':
        try:
            self.do_signup(qcontext)
            User = request.env['res.users']
            user_sudo = User.sudo().search(
                User._get_login_domain(qcontext.get('login')),
                order=User._get_login_order(), limit=1
            )
            template = request.env.ref(
                'auth_signup.mail_template_user_signup_account_created',
                raise_if_not_found=False)
            if user_sudo and template:
                template.sudo().send_mail(user_sudo.id, force_send=True)
            return self.web_login(*args, **kw)
        except UserError as e:
            qcontext['error'] = e.args[0]
        except (SignupError, AssertionError) as e:
            if request.env["res.users"].sudo().search(
                    [("login", "=", qcontext.get("login"))]):
                qcontext["error"] = _("Another user is already registered"
                                      " using this email address.")
            else:
                _logger.error("%s", e)
                qcontext['error'] = _("Could not create a new account.")
    elif 'signup_email' in qcontext:
        user = request.env['res.users'].sudo().search(
            [('email', '=', qcontext.get('signup_email')),
             ('state', '!=', 'new')], limit=1)
        if user:
            return request.redirect('/web/login?%s' % url_encode(
                {'login': user.login, 'redirect': '/web'}))
    response = request.render('auth_signup.signup', qcontext)
    response.headers['X-Frame-Options'] = 'SAMEORIGIN'
    response.headers['Content-Security-Policy'] = "frame-ancestors 'self'"
    return response

Hope it helps

for python

class AuthSignupHomePage(AuthSignupHome):
    @http.route('/web/signup', type='http', auth='public', website=True, sitemap=False)
    def web_auth_signup(self, *args, **kw):
        qcontext = self.get_auth_signup_qcontext()
        web_company = request.env.company

        res = super(AuthSignupHomePage, self).web_auth_signup()
        user = request.env['res.users'].sudo().search([("login", "=", qcontext.get("login"))])
        user.sudo().write({
        'sex': kw.get('sex'),
                })
        return res

    def get_auth_signup_qcontext(self):
        qcontext = super(AuthSignupHomePage, self).get_auth_signup_qcontext()
        sex = request.env['res.partner']._fields['sex'].selection
        # print("dddddddddddddddddddddddddddddddddd", sex)
qcontext['sex'] = sex
        return qcontext

for xml 

id="signup_edit" name="edit signup" inherit_id="auth_signup.fields" >

     expr="//div[hasclass('field-confirm_password')]" position="after">
  
  
t-attf-class="form-group ">
        for="sex" >Sex