Rails calling create method from same controller instance variable - ruby-on-rails

Question

I have a few hours with something that is probably very easy.
I have a nested model
resources :grades do
resources :students
end
So I defined
before_action :set_grade, except: [:mass_input]
to my students_controller
def set_grade
#grade = Grade.find(params[:grade_id])
end
I'm very good with this, the problem is that now I'm using another action that takes :grade_id from another source, so I cant use set_grade, instead I'm passing the id with javascript. Works.
My problem appears here, when I try to call to create method, I'm probably doing it wrong ..
def mass_input
#grade = Grade.find(#data['grade'])
#data = JSON.parse(params[:form_data])
#is this create way ok or I'm overriding???
Student.create(:rut => #data['mass_students'][1][0], :nombre => #data['mass_students'][1][1], :apellido => #data['mass_students'][1][2])
end
This is my create action
def create
#student = Student.new(student_params)
#grade.students << #student
respond_to do |format|
if #student.save
format.html { redirect_to school_grade_path(#grade.school,#grade), notice: 'Alumno creado con éxito.' }
format.json { render :show, status: :created, location: #student }
else
format.html { render :new }
format.json { render json: #student.errors, status: :unprocessable_entity }
end
end
end
By this way code works but this line is not working
#grade.students << #student
#grade is not passing from mass_input to create. I think I'm not calling create properly but I cant find how to do it , because is not redirecting neither
My mass_input action is working by this way
def mass_input
#grade = Grade.find(#data['grade'])
#data = JSON.parse(params[:form_data])
Student.create(:rut => #data['mass_students'][1][0], :nombre => #data['mass_students'][1][1], :apellido => #data['mass_students'][1][2])
grade.students << student
respond_to do |format|
if student.save
format.html { redirect_to school_grade_path(grade.school,grade), notice: 'Alumno creado con éxito.' }
format.json { render :show, status: :created, location: student }
else
format.html { render :new }
format.json { render json: student.errors, status: :unprocessable_entity }
end
end
end
but I think is AWFUL, I must use my own create action
Thanks!!

Answer 1

Oh... From my point of view you are doing smth strange... The fast solution for your issue would be smth like this:
1) Rewrite before action in a new way:
before_action :set_grade
And method set_grade:
def set_grade
#grade = Grade.find(params[:grade_id].presence || #data['grade'])
end
2) Set method for student params
def student_params
data = JSON.parse(params[:form_data])['mass_students']
#Transform data to be student params. For ex:
data.map{|_key, info| {:rut => info[0], :nombre => info[1], :apellido => info[2]}}
end
3) Rewrite mass_input method
def mass_input
respond_to do |format|
if (#students = #grade.students.create(student_params).all?(&:persisted?)
#some actions when everything is great.
else
#some actions if not of them valid (maybe redirect & show info about not created students)
end
end
end
But you should definetly read more rails guides... http://guides.rubyonrails.org/

Answer 2

Sorry, I couldn't comment it. So I can just post a reply, it is not an complete answer though. In the student controller
Try to use
#student = #grade.students.new
or
#student = Student.new
#student.grade = #grade or #student.grade_id = params[:grade_id]
So when you do #student.save, you won't need to do the line below, and it will still work
#grade.students << #student

Answer 3

Ruby on rails has conventions you should follow to simplify lots of things. The first thing I see here is that in your def mass_input, you are using
Student.create(...)
The method create, as it says, creates an object but also saves it into database. So you should have new instead of create because new does not save it to database, just instantiates it:
#student = Student.new
...inside def mass_input, and by default the submit action in your view will take your object to the create method (if the object is new it goes to create, other way it goes to update, thanks to Rails). For this you could take a look at http://guides.rubyonrails.org/action_controller_overview.html
About the line #grade.students << #student, I assume you are intending to add the newly created student to his grade. See this example of usage of nested resources when trying to create, edit or destroy http://railscasts.com/episodes/139-nested-resources. In any case, nested resources implies this:
class Grade < ActiveRecord::Base
has_many :student
end
class Student < ActiveRecord::Base
belongs_to :grade
end
So, in your model Student you should have a column to store the Grade of that student. And then in your params you should receive the actual grade and store it in the grade_id inside your #student.
If something is not clear, I suggest you to take a look at the nested resources guide http://guides.rubyonrails.org/routing.html#nested-resources
As a commentary, << is used to add "things" to the end of an array, i.e. if you want to quickly store in an array some info you use:
array = []
Student.all.each do |s|
array << s.name
end
It will store in the array all the names of your students. Obviously there is a simpler way to do this by doing this:
Student.pluck(:name)