How to access variables and methods across controllers in Rails - ruby-on-rails

Question

Books Controller:
class BooksController < ApplicationController
before_action :set_book, only: [:show, :edit, :update, :destroy]
# GET /books
# GET /books.json
def index
if params[:student_id]
student = Student.find(params[:student_id])
#books = student.books
else
#books = Book.all
end
respond_to do |format|
format.html
format.csv {render text: #books.to_csv }
end
end
def show
end
def new
#book = Book.new
end
def edit
end
def create
#book = Book.new(book_params)
respond_to do |format|
if #book.save
format.html { redirect_to #book, notice: 'Book was successfully created.' }
format.json { render :show, status: :created, location: #book }
else
format.html { render :new }
format.json { render json: #book.errors, status: :unprocessable_entity }
end
end
end
def update
respond_to do |format|
if #book.update(book_params)
format.html { redirect_to #book, notice: 'Book was successfully updated.' }
format.json { render :show, status: :ok, location: #book }
else
format.html { render :edit }
format.json { render json: #book.errors, status: :unprocessable_entity }
end
end
end
def destroy
#book.destroy
respond_to do |format|
format.html { redirect_to books_url, notice: 'Book was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_book
#book = Book.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def book_params
params.require(:book).permit(:book_name, :book_level, :total_words, :words_wrong, :self_corrections, :student_id)
end
end
Here is my "Students Controller"
class StudentsController < ApplicationController
def show
#student = Student.find(params[:id]) rescue nil
#books = Book.where(student_id: params[:id])
#book = Book.new
end
def create
student = Student.new(student_parameters)
student.user_id = current_user.id
if student.save
redirect_to student
else
redirect_to 'students#index'
end
end
def index
#students = Student.where("user_id = ?",current_user.id)
#student = Student.new
end
private
def student_parameters
params.require(:student).permit(:first_name, :last_name)
end
end
Books belong to students, and on the index view where I show an individual's students books, I want the heading at the top of the page to say "{current student}'s book". I'm unsure as to how to call the name of the current student, and I think the source of my confusion is the fact that I'm working with the books controller and student.first_name and student.last_name aren't available to me.
Additionally, I would like to know how to access book data when I'm using the students controller. For instance when I'm at localhost:3000/students/2, I'd like to show all that students books.
I'm looking for something like current_student.books or current_student.name, I think, but I'm not sure how to create them.

Answer 1

Instead of doing...
student = Student.find(params[:student_id])
#books = student.books
do...
#student = Student.find(params[:student_id])
#books = #student.books
This gives you the instance variable #student that you can use in your views, in particular #student.first_name and #student.last_name
you may want to condition the code in the view so that it only shows if #student is not nil (it would be nil if params[:student_id] wasn't passed).