When I change my code like this, anythings are not shown at the Expense tag.

myiew.xml

<odoo>

  <data>

    <record model = "ir.ui.view" id = "custom_expense.list">

      <field name = "name"> custom_expense list </field>

      <field name = "model"> custom_expense.custom_expense </field>

      <field name = "arch" type = "xml">

        <tree>

          <field name = "name" />

        </tree>

      </field>

    </record>

    <record model = "ir.ui.view" id = "custom_expense.form">

      <field name = "name"> custom_expense form </field>

      <field name = "model"> custom_expense.custom_expense </field>

      <field name = "arch" type = "xml">

        <form>

          <sheet>

            <notebook>

              <page string = "Expense">

                  <tree>

                      <field name = "name" />

                      <field name = "date" />

                      <field name = "analytic_account_id" groups = "analytic.group_analytic_accounting" />

                      <field name = "analytic_tag_ids" widget = "many2many_tags" groups = "analytic.group_analytic_tags" />

                  </tree>

              </page>

              <page string = "Other Info">

              </page>

            </notebook>

          </sheet>

        </form>

      </field>

    </record>

    <record model = "ir.actions.act_window" id = "custom_expense.action_window">

      <field name = "name"> custom_expense </field>

      <field name = "res_model"> custom_expense.custom_expense </field>

      <field name = "view_mode"> tree, form </field>

    </record>

    <menuitem name = "custom_expense" id = "custom_expense.menu_root" action = "custom_expense.action_window" />

  </data>

</odoo>

mymodel.py

from odoo import models, fields, api

class custom_expense (models.Model):

    _name = 'custom_expense.custom_expense'

    test = fields.Char (string = 'Valuethird') 

    hr_expense_id = fields.Many2one ('hr.expense', string = 'Expense')

    name = fields.Char (related = 'hr_expense_id.name')

    date = fields.Date (related = 'hr_expense_id.date')

    analytic_account_id = fields.Many2one (related = 'hr_expense_id.analytic_account_id')

    analytic_tag_ids = fields.Many2many (related = 'hr_expense_id.analytic_tag_ids')

But I want to get like this(https://drive.google.com/open?id=1ODOSWUxwzPvDy0U0BmyfEY70gcgHoFms). I thought if I inherit the hr.expense model I can display any fields from the parent model (hr.expense) to my custom view. I tried if I inherit hr.expense view to my custom view, it also changes the parent view. I also don't want to do that.

Hi,

Try the following code

.py

from odoo import models, fields, api

class CustomExpense (models.Model):

    _name = 'custom.expense'
    test = fields.Char(string='Valuethird')
    hr_expense_id = fields.Many2one('hr.expense', string='Expense')

.xml

<odoo>
    <data>
        <record model="ir.ui.view" id="custom_expense.list">
            <field name="name">custom_expense_list</field>
            <field name="model">custom.expense</field>
            <field name="arch" type="xml">
                <tree>
                    <field name="test"/>
                    <field name="hr_expense_id"/>
                </tree>
            </field>
        </record>
        <record id="action_custom_expense_form" model="ir.actions.act_window">
            <field name="name">Custom Expense</field>
            <field name="res_model">custom.expense</field>
            <field name="view_mode">tree,form</field>
        </record>
        <menuitem name="custom_expense" id="custom_expense.menu_root" action="action_custom_expense_form"/>
    </data>
</odoo>

Regards