Question

Just to simplify my question here: Update Geocode latitude and logitude everytime address is updated

I wanna do this:

Two input field for user to enter values for A, B. When it is saved, value A and B are saved to the database. In the database column, there is a column C, which dynamically C = A + B.

First save:

A = 1
B = 2
C = A + B = 3

Then when user updates value for A and B, C is also changed dynamically and replace the new sum value in the database.

A = 2
B = 2
Now C will calculate: C = A + B = 4

Now value C is 4 instead of 3.

Can anyone write this thing in Rails? Thanks.

Answer 1

I can!

The key are callbacks. This will update C before you save the object.

before_save :update_c

def update_c
  self.c = a + b
end