Form submission help needed - ruby-on-rails

Question

I'm developing a small project using Ruby on Rails where basically student can sign up for a study room. I have one modification that I'm trying to make that I can't figure out yet.
On default when I create new submission, it creates it and goes to the view screen that basically shows all the info from the submission. Here is the controller for the form:
# POST /students
# POST /students.json
def create
#student = Student.new(params[:student])
respond_to do |format|
if #student.save
format.html { redirect_to #student, notice: 'Student was successfully created.' }
format.json { render json: #student, status: :created, location: #student }
else
format.html { render action: "new" }
format.json { render json: #student.errors, status: :unprocessable_entity }
end
end
end
What I'm trying to do is when the user clicks the submit button it doesn't automatically save it to the DB, but instead it goes to the next screen where the user can review their submission and confirm the submission by clicking the button. Once they click the confirm button it should save it to the DB and show the 'Student was successfully created.' notice and take them back to the form screen.
Here is the controller for the show (which is the next page that gets displayed):
# GET /students/1
# GET /students/1.json
def show
#student = Student.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.json { render json: #student }
end
end

Answer 1

Some key points:
Don't use #show to display the preview. #show is supposed to display normal persist objects, while your new object is not persist yet. You also need extra element on preview such as "confirm" link/button.
It's better to use a separate #preview action, which accepts form submit from #new, and will send confirmed object to #create.
You need a vehicle to pass object in #preview, both force(to #create) and back(to #new if not satisfied). Though I don't like to use session, it seems there are not too much choices.
The example code:
def new
#student = session[:student].blank? ? Student.new : session[:student]
# ...
render
end
def preview
#student = Student.new(params[:student])
session[:student] = #student
# ....
render
end
def create
#student = session[:student]
session[:student].clear
# ...
render
end
Add
More about #3. In #create you need params to build a new object with full data to save. However in this case the form is not submitted to #create but #preview instead. So how do you get the data? There are three ways:
a. Plain display(just like #show). In #preview, build a form with hidden fields filled with data sent by #new.
b. Plain display. Use session to pass data instead of form. Much simple than #a.
c. Show both plain text and a form in #preview. User can preview the submission and edit it right in #preview.
According to your need, #b and #c are all good IMO.