ruby on rails: instance variable returns nil - ruby-on-rails

Question

I've been trying to push the input data from my form to the database using the create function, but the instance variable in create function keeps returning 'nil' and after the 'begin transaction', it does 'rollback transaction'
The model function works fine as I get the desired parsed data, and so does the timetables_params function. But timetables_params[:start_time] always returns 'nil' even though the timetables_params returns all the start_time values and end_time values.
How can I fix this?
Here is my controller
def index
#user = current_user
#timetables = #user.timetable.all
end
def new
#timetable = Timetable.new
end
def create
timetables_params[:start_time] = Timetable.parse_timetable_time(timetables_params, 'start')
timetables_params[:end_time] = Timetable.parse_timetable_time(timetables_params, 'end')
#timetable = Timetable.create(timetables_params)
if #timetable.save
flash[:success] = "Done"
else
render 'new'
end
end
private
def timetables_params
params.require(:timetable).permit(:user_id, :start_time, :end_time)
end
end
Here is my model
belongs_to :user
attr_accessor :user, :start_time, :end_time
def self.parse_timetable_time(hash, type)
date_string = hash["#{type}_time(1i)"].to_s + "=" + hash["#{type}_time(2i)"].to_s + "=" + hash["#{type}_time(3i)"]
Time.parse(date_string)
end

Answer 1

You probably have not set the user since its belongs_to :user and i dont see it anywhere in your code. That's why its rolling back and you probably required user_id in your Timetable model. My suggestion is below
Instead of:
#timetable = Timetable.create(timetables_params)
Use build:
#timetable = current_user.timetables.build(timetables_params)

Answer 2

Thanks for all the help above, but turns out that I just had to add the following lines in the model and modify the controller create function:
model
validates :user_id, presence: true
validates :start_time, :end_time, presence: true
controller
def create
#timetable = current_user.timetables.build(timetables_params)
if #timetable.save
flash[:success] = "Done"
else
render 'new'
end
And, I don't necessarily need to parse the datetime values, Rails does do it automatically