While saving simple_form data, rails save values as NULL problem

Problem solution is here.

The model you have are heavily populated with attr_accessor. attr_accessor is a way to create "virtual attributes" in Ruby / Rails, as it defines a custom getter and setter method, which will essentially define the "attributes" for use on the system

The problem you have is attr_accessor, in the simplest of terms, will not permit your data to be saved in the database. This will be one of the bigger issues you have - you need to get rid of any attr_accessors which override your database attributes.

It should be removed the attr_accessor methods from your model