Hi, In my opinion,2 ways solved it: 1. change the field's attribute of the order object, exmpale:

'shop_id': fields.many2one('sale.shop', 'Shop', required=True, readonly=True, states={'draft': [('readonly', False)], 'sent': [('readonly', False)]}),

only the draft and sent state the fields can be edited

2. add access rule for the object

Settings >> Technical >> Security >> Record Rules

remove Apply for Write..

then set the domain filtter example:

 [('state', '=', 'Quotation')]...

Hope it wil help you

HI,

Go in Settings >> Technical >> Security >> Access Controls List

Search Purchase you file find access control list for purchase order remove write access as show in screen shot.

To see screen shot click here