Actually I am using odoo online but I have created a new field named x_old_date_order but it doesn't show in po form.

first add the field name any name you want 


add automation action 
state =sales order 

3 add this code in python 

if record.x_studio_old_order_date_1:

    record.write({

        'date_order':record.x_studio_old_order_date_1

    })

 
for inventory same step 


for inventory same add field 

for invensible condition 
state == "draft"
for require 

for read only 


after than add automation action 

and add this code for python 

if record.scheduled_date:

    record.write({

        'date_done':record.scheduled_date

    })

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