ActiveModel::MissingAttributeError in Controller can't write unknown attribute - ruby-on-rails

Question

For one of the views in my rails application, I have set up the controller as such. I want to get all students records from the db and append extra values to each student. This is giving me the error:
ActiveModel::MissingAttributeError in MemoMainTesterController#test_students
can't write unknown attribute current_target
class MemoMainTesterController < ApplicationController
def test_students
#all_students = Student.all
#all_students.each do |student|
current = current_target(student)
previous_test_info = last_pass(student)
student[:current_target] = current[0]
student[:current_level] = current[1]
student[:current_target_string] = "Level #{current[0]} - Target #{current[1]}"
student[:last_pass] = previous_test_info[0]
student[:attempts] = previous_test_info[1]
student[:last_pass_string] = previous_test_info[2]
end
end
.
.
.
end
It occurs specifically where student[:current_target] = current[0].
Am I not allowed to append extra values to this hash?
Is there a workaround for this?
EDIT: Although Student.all is a model instance, I want to turn it into a hash and append more key value pairs to it.

Answer 1

In your case, student is not a Hash but a Student model instance.
When you call student[:current_target] you are attempting to write Student's current_target attribute, which surely is not an actual attribute in the DB for students table. Hence the error.
To obtain a hash from your models containing the extra data, you may consider this refactor:
class MemoMainTesterController < ApplicationController
def test_students
#all_students = Student.all
#students_with_steroids = #all_students.map do |student|
current = current_target(student)
previous_test_info = last_pass(student)
student_attributes = student.attributes # <= this is a hash, that you store in student_attributes hash variable
student_attributes.merge(current_target: current[0],
current_level: current[1],
current_target_string: "Level #{current[0]} - Target #{current[1]}",
last_pass: previous_test_info[0],
attempts: previous_test_info[1],
last_pass_string: previous_test_info[2])
end
end