Rails Nested Attributes properly assigning parent_id as index, but isn't assigning additional attributes

Question

I've been working on implementing a new model that belongs to one of our web apps existing models. Eventually, I want to build out a nested form. I understand that the form, and strong params can have it's own suite of issues, but I am currently struggling to get the models to behave as I would expect in the rails console.

Rails 4.2.7, Postgres DB

UPDATE - 10/3/16 - Still trying to find the right solution, but have made some changes

Our work is with Schools and Districts, and this particular case deals with surveys and how a survey is assigned to a school and district. Until now, a survey has been assigned to a district with a SurveyAssignment model, and some down the line logic assumed that all schools in a district were also "assigned" to the survey. Now, we want to be able to add more granularity to the SurveyAssignment and allow some specificity at the school level.

So I created a SchoolSurveyAssignment model and started to get the bits in place.

Here is the relevant model info:

class District < ActiveRecord::Base
  ...
  has_many :schools, dependent: :destroy
  has_many :survey_assignments, dependent: :destroy
  ...
end

class School
  ...
  belongs_to :district
  has_many :school_survey_assignments
  has_many :survey_assignments, :through => :school_survey_assignments

  ...
end

class SurveyAssignment
  belongs_to :district
  belongs_to :survey
  has_one :survey_version, through: :survey
  has_many :school_survey_assignments, inverse_of: survey_assignment
  has_many :schools, :through => :school_survey_assignments

  accepts_nested_attributes_for :school_survey_assignments

  attr_accessor :survey_group, :survey_version_type, :survey_version_id, :school_survey_assignments_attributes
  validates :survey_id, presence: true
end 

class SchoolSurveyAssignment
  belongs_to :survey_assignment, inverse_of: :school_survey_assignments
  belongs_to :school

  attr_accessor :school_id, :survey_assignment_id, :grades_affected, :ulc_affected
  validates_presence_of :survey_assignment
  validates :school_id, presence: true, uniqueness: {scope: :survey_assignment_id}
end

Relevant Controller code:

class SurveyAssignmentsController < ApplicationController
  before_action :set_district
  before_action :set_survey_assignment, only: [:show, :edit, :update, :destroy]

  respond_to :html, :json, :js

  def new
    @new_survey_assignment = SurveyAssignment.new()
    @district.schools.each do |school|
      @new_survey_assignment.school_survey_assignments.build(school_id: school.id)
    end
  end

  def create
    @survey_assignment = SurveyAssignment.new(survey_assignment_params)
    if @survey_assignment.save
      flash[:notice] = "Survey successfully assigned to #{@district.name}"
    else
      flash[:alert] = "There was a problem assigning this survey to #{@district.name}"
    end
    redirect_to district_survey_assignments_path(@district)
  end

  def survey_assignment_params
    params.require(:survey_assignment).permit(:survey_id, :status, :survey_version_id, school_survey_assignments_attributes: [:id, :survey_assignment_id, :school_id, grades_affected: [], ulc_affected: []]).tap do |p|
      p[:district_id] = @district.id
      p[:school_year] = session[:selected_year]
    end
  end

  def set_district
    @district = District.find(params[:district_id])
  end

Here is the relevant schema info:

create_table "school_survey_assignments", force: :cascade do |t|
  t.integer "survey_assignment_id"
  t.integer "school_id"
  t.integer "grades_affected",      default: [], array: true
  t.string  "ulc_affected",         default: [], array: true
 end

add_index "school_survey_assignments", ["school_id"], name: "index_school_survey_assignments_on_school_id", using: :btree
add_index "school_survey_assignments", ["survey_assignment_id"], name: "index_school_survey_assignments_on_survey_assignment_id", using: :btree

create_table "survey_assignments", force: :cascade do |t|
  t.integer  "district_id"
  t.integer  "survey_id"
  t.integer  "status"
  t.datetime "created_at"
  t.datetime "updated_at"
  t.integer  "school_year"
  t.integer  "last_response_status_id"
end

add_index "survey_assignments", ["district_id"], name: "index_survey_assignments_on_district_id", using: :btree

Once these were in place, I stepped into my rails console and attempted the following:

2.3.1 :002 > sa1 = SurveyAssignment.create(district_id: 3, survey_id: 508, school_year: 2017)
  (0.2ms)  BEGIN
 SQL (0.7ms)  INSERT INTO "survey_assignments" ("district_id", "survey_id", "school_year", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["district_id", 3], ["survey_id", 508], ["school_year", 2017], ["created_at", "2016-09-30 21:30:20.205144"], ["updated_at", "2016-09-30 21:30:20.205144"]]
  (7.2ms)  COMMIT
=> #<SurveyAssignment id: 369, district_id: 3, survey_id: 508, status: nil, created_at: "2016-09-30 21:30:20", updated_at: "2016-09-30 21:30:20", school_year: 2017, last_response_status_id: nil>
2.3.1 :003 > sa2 = SurveyAssignment.create(district_id: 3, survey_id: 508, school_year: 2017)
  (0.3ms)  BEGIN
 SQL (0.4ms)  INSERT INTO "survey_assignments" ("district_id", "survey_id", "school_year", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["district_id", 3], ["survey_id", 508], ["school_year", 2017], ["created_at", "2016-09-30 21:30:30.701197"], ["updated_at", "2016-09-30 21:30:30.701197"]]
  (0.5ms)  COMMIT
=> #<SurveyAssignment id: 370, district_id: 3, survey_id: 508, status: nil, created_at: "2016-09-30 21:30:30", updated_at: "2016-09-30 21:30:30", school_year: 2017, last_response_status_id: nil>

So now, I've successfully created two Survey Assignments. I'm now going to create two School Survey Assignments off of sa1:

2.3.1 :004 > [{school_id: 5}, {school_id: 6}].each do |ssa|
2.3.1 :005 >     sa1.school_survey_assignments.create(ssa)
2.3.1 :006?>   end
  (0.2ms)  BEGIN
 SchoolSurveyAssignment Exists (2.4ms)  SELECT  1 AS one FROM "school_survey_assignments" WHERE ("school_survey_assignments"."school_id" = 5 AND "school_survey_assignments"."survey_assignment_id" = 369) LIMIT 1
 SQL (0.4ms)  INSERT INTO "school_survey_assignments" ("survey_assignment_id") VALUES ($1) RETURNING "id"  [["survey_assignment_id", 369]]
  (6.4ms)  COMMIT
  (0.6ms)  BEGIN
 SchoolSurveyAssignment Exists (0.4ms)  SELECT  1 AS one FROM "school_survey_assignments" WHERE ("school_survey_assignments"."school_id" = 6 AND "school_survey_assignments"."survey_assignment_id" = 369) LIMIT 1
  SQL (0.3ms)  INSERT INTO "school_survey_assignments" ("survey_assignment_id") VALUES ($1) RETURNING "id"  [["survey_assignment_id", 369]]
  (0.4ms)  COMMIT
=> [{:school_id=>5}, {:school_id=>6}]
2.3.1 :007 > sa1.save
  (0.3ms)  BEGIN
  (0.4ms)  COMMIT
=> true

Now, it looks like I've successfully created two SchoolSurveyAssignments with survey_assignment_id = 369 and school_ids = 5 and 6

2.3.1 :008 > sa1.school_survey_assignments
  SchoolSurveyAssignment Load (0.3ms)  SELECT "school_survey_assignments".* FROM "school_survey_assignments" WHERE "school_survey_assignments"."survey_assignment_id" = $1  [["survey_assignment_id", 369]]
=> #<ActiveRecord::Associations::CollectionProxy [#<SchoolSurveyAssignment id: 5, survey_assignment_id: 369, school_id: nil, grades_affected: [], ulc_affected: []>, #<SchoolSurveyAssignment id: 6, survey_assignment_id: 369, school_id: nil, grades_affected: [], ulc_affected: []>]>

As you can see from the ActivRecord::Associations::CollectionProxy, both of the SchoolSurveyAssignments were created, with survey_assignment_id: 369, but with a nil school_id. This is troubling as it seems to be

1. Ignoring the parameters being passed into the create function, and
2. ignoring the validation of school_id

Another item that I don't understand is the following:

2.3.1 :009 > SchoolSurveyAssignment.find(5).survey_assignment_id
  SchoolSurveyAssignment Load (0.6ms)  SELECT  "school_survey_assignments".* FROM "school_survey_assignments" WHERE "school_survey_assignments"."id" = $1 LIMIT 1  [["id", 5]]
=> nil
2.3.1 :011 > SchoolSurveyAssignment.find(5).survey_assignment.id
  SchoolSurveyAssignment Load (0.3ms)  SELECT  "school_survey_assignments".* FROM "school_survey_assignments" WHERE "school_survey_assignments"."id" = $1 LIMIT 1  [["id", 5]]
  SurveyAssignment Load (0.4ms)  SELECT  "survey_assignments".* FROM "survey_assignments" WHERE "survey_assignments"."id" = $1 LIMIT 1  [["id", 369]]
 => 369

Calling .survey_assignment_id should return the attribute on the SchoolSurveyAssignment and give 369. .survey_assignment.id is simply just grabbing the parent object's ID. I would expect both to return the same value, but one returns nil.

The end use case is making a SurveyAssignment form that lets the user set the attributes for a new SurveyAssignment and also set the attributes for X number of SchoolSurveyAssignments (based on # of schools in a district; varies from 2 to 15). Once I get a better grasp on how these models are interacting, I feel confident in executing this goal, but the behavior I'm seeing doesn't make sense to me, and I was hoping to find some clarity on implementing these related models. I feel like I'm bouncing around the answer, but am missing a key detail.

Thanks,

Alex

Answer 1

Try removing your attr_accessor lines of code. attr_accessor shouldn't be used for attributes that are persisted in the database and it's probably messing up the methods that ActiveRecord already provides by default, causing those attributes to not be saved properly

class SurveyAssignment
  belongs_to :district
  belongs_to :survey
  has_one :survey_version, through: :survey
  has_many :school_survey_assignments, inverse_of: survey_assignment
  has_many :schools, :through => :school_survey_assignments

  accepts_nested_attributes_for :school_survey_assignments

  validates :survey_id, presence: true
end 

class SchoolSurveyAssignment
  belongs_to :survey_assignment, inverse_of: :school_survey_assignments
  belongs_to :school

  validates_presence_of :survey_assignment
  validates :school_id, presence: true, uniqueness: {scope: :survey_assignment_id}
end