Cannot Update field from another doctype

Hello Guys,
So i have been trying to update the odometer/mileage field of the default Vehicle doctype from a custom doctype i have called “Vehicle Service Log” i have tried updating it through the server and client side and i keep getting the same error on both
and a CannotChangeConstantError is thrown
i have created a custom field in the doctype and tried placing my value there and it worked properly , i am curious about the fact that i cannot update that particular field ,
an explanation will be very much appreciated. Thanks

When you set up a Vehicle, you have to enter the starting Odometer value (which cannot be changed). Any subsequent updates that you make need to be done through Vehicle Log doctype. Why create a custom doctype “Vehicle Service Log” when “Vehicle Log” can serve the same purpose?


how to get vehicle-doc.type odometer value (last) to shown in another one doc type field name.

eg : last vehicle odometer value is :10000

the same values shown in another one doc.type field.

pl explain

@Sendilkumar i’m sorry i’m not sure i fully understand you, do you want to display the odometer value of a vehicle on another doctype form???

@Ebuka_Joseph_Akeru, i have already entered odometer value of 16000 in vehicle doc type .
i want to display the last value of 16000 in vehicle log doc type.