Rails -- ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: - activerecord

Question

Having major Rails issues currently. I'm creating a School-Dashboard app that takes an xref table called Enrollments that relates Courses and Students.
Any time I try to update a grade for an Enrollment, I constantly get this line
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: UPDATE
"enrollments" SET "grade" = ?, "updated_at" = ? WHERE "enrollments"."" IS NULL
This line does not appear when I update attributes for Courses or Students. Only for the :grade attribute in Enrollment.
For some reason, it isn't being read properly, even though it is a legitimate attribute in my db for Enrollment (check out my schema).
I do all of my preliminary work in the rails sandbox.
Using ruby 2.1.1, Rails 4.1.0.rc1
I'd really love some help here.
Here are my corresponding models
class Student < ActiveRecord::Base
has_many :enrollments
has_many :courses, through: :enrollments
end
class Course < ActiveRecord::Base
has_many :enrollments
has_many :students, through: :enrollments
end
class Enrollment < ActiveRecord::Base
belongs_to :student
belongs_to :course
end
The controllers:
Students
class StudentsController < ApplicationController
def index
#students = Student.all
end
def new
#student = Student.new
end
def show
end
def update
#student.update_attributes(student_params) ? redirect_to #student : render 'edit'
end
def create
#student = Student.new(student_params)
#student.save ? redirect_to #student : render 'new'
end
def destroy
end
def edit
end
private
def student_params
params.require(:student).permit(:first_name, :last_name, :student_number, :email)
end
end
Courses
class CoursesController < ApplicationController
def index
#courses = Course.all
end
def new
#course = Course.new
end
def show
end
def update
#course.update_attributes(course_params) ? redirect_to #course : render 'edit'
end
def create
#course = Course.new(course_params)
#course.save ? redirect_to #course : render 'new'
end
def destroy
end
def edit
# code here
end
private
def course_params
params.require(:course).permit(:course_name, :course_number)
end
end
Enrollments
class EnrollmentsController < ApplicationController
attr_accessor :course_id, :student_id, :grade
def index
#enrollments = Enrollment.all
end
def new
#enrollment = Enrollment.new
end
def create
#enrollment = Enrollment.new(enrollment_params)
#enrollment.save ? redirect_to #enrollment : render 'new'
end
def update
#enrollment.update_attributes(enrollment_params) ? redirect_to #enrollment : render 'edit'
end
def show
end
def destroy
#enrollment.destroy
end
def edit
# code here
end
private
def enrollment_params
params.require(:enrollment).permit(:course_id, :student_id, :grade)
end
end
And finally my schema.rb
ActiveRecord::Schema.define(version: 20140417152720) do
create_table "courses", force: true do |t|
t.string "course_name"
t.integer "course_number"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "enrollments", id: false, force: true do |t|
t.integer "course_id", null: false
t.integer "student_id", null: false
t.decimal "grade", precision: 5, scale: 2
t.datetime "created_at"
t.datetime "updated_at"
end
# noinspection RailsParamDefResolve
add_index "enrollments", ["course_id", "student_id"], name: "index_enrollments_on_course_id_and_student_id"
# noinspection RailsParamDefResolve
add_index "enrollments", ["student_id", "course_id"], name: "index_enrollments_on_student_id_and_course_id"
create_table "students", force: true do |t|
t.string "first_name"
t.string "last_name"
t.string "email"
t.integer "student_number"
t.datetime "created_at"
t.datetime "updated_at"
end
end

Answer 1

Looks like I figured it out on my own!
So here's a bit of rails convention that needs to be addressed. The problem was with my database setup for 'Enrollments'. When I run the command
rails g migration CreateJoinTableEnrollments course student
Rails does too much work for me in my migration file (except for the table name and grade, I added that)
class CreateJoinTableEnrollments < ActiveRecord::Migration
def change
create_join_table :courses, :students, table_name: :enrollments, id: false, force: true do |t|
t.index [:course_id, :student_id], null: false
t.index [:student_id, :course_id], null :false
t.decimal :grade, precision: 5, scale: 2
t.timestamps
end
end
end
In reality, I didn't need any of that. In order to manipulate specific data in a row for Enrollments, there has to be an identifier for that row. With id: false, force: true that option got nullified. I also simplified things with the indexing. I just created regular old columns instead. Now my migration file looks like this.
class CreateJoinTableEnrollments < ActiveRecord::Migration
def change
create_table :enrollments do |t|
t.integer :course_id, null: false
t.integer :student_id, null: false
t.decimal :grade, precision: 5, scale: 2
t.timestamps
end
end
end
And with that, no issues! I've just been breaking my head over that for the past 2 days. Hope this helps anyone else who has this issue.