I have 2 model: Contract & Room. 

In model room I have a selection field to set state for room. 

They are my model:

- Room:

	​
class PmaApartmentRoom(models.Model):    
	​_inherit = "pma.apartment.room"
    contract = fields.One2many("pma.contract", "room", string="Contract")
    state = fields.Selection([
	​	​("available", "Available"),
	​	​("rented", "Rented")],
	​	​string="Status", copy=False, 
	​	​index=True, readonly=True, store=True, tracking=True)


 
class PmaContract(models.Model):    
	​_name = "pma.contract"   
	​_inherit = ["mail.thread", "mail.activity.mixin"]   
	​_description = "Manage contract"
    state = fields.Selection([
	​	​("draft", "Draft"),            
	​	​("to_link", "To link"), 
        	​("active", "Active"),
         ("expired", "Expired"),  
         ("liquidated", "Liquidated")],        
	​	​string="Status", default="draft", copy=False,       
	​	​ index=True, readonly=True, store=True, tracking=True,)
    
	​room = fields.Many2one("pma.apartment.room", string="Room name",        	​	​domain="[('apartment', '=', apartment)]",        	​	​	​	​	​	​ondelete="restrict", store=True, required=True, tracking=True)


State of contract = "active" => state of room = "rented".

State of contract in ["draft", "to_link", "expried", "liquidated"] => state of room = "available"


Please help me ....