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

for 1 of views in rails application, have set controller such. want students records db , append values each student. giving me 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 |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 student[:current_target] = current[0].

am not allowed append values hash? there workaround this?

edit: although student.all model instance, want turn hash , append more key value pairs it.

in case, student not hash student model instance.

when call student[:current_target] attempting write student's current_target attribute, surely not actual attribute in db students table. hence error.

to obtain hash models containing data, may consider refactor:

class memomaintestercontroller < applicationcontroller   def test_students     @all_students = student.all     @students_with_steroids = @all_students.map |student|       current            = current_target(student)       previous_test_info = last_pass(student)       student_attributes = student.attributes # <= hash, 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