I have a functioning Rails 3 app that uses has_many :through associations which is not, as I remake it as a Rails 4 app, letting me save ids from the associated model in the Rails 4 version.
These are the three relevant models are the same for the two versions.
Categorization.rb
class Categorization < ActiveRecord::Base
belongs_to :question
belongs_to :category
end
Question.rb
has_many :categorizations
has_many :categories, through: :categorizations
Category.rb
has_many :categorizations
has_many :questions, through: :categorizations
In both apps, the category ids are getting passed into the create action like this
"question"=>{"question_content"=>"How do you spell car?", "question_details"=>"blah ", "category_ids"=>["", "2"],
In the Rails 3 app, when I create a new question, it inserts into questions table and then into the categorizations table
SQL (82.1ms) INSERT INTO "questions" ("accepted_answer_id", "city", "created_at", "details", "province", "province_id", "question", "updated_at", "user_id") VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?) [["accepted_answer_id", nil], ["city", "dd"], ["created_at", Tue, 14 May 2013 17:10:25 UTC +00:00], ["details", "greyound?"], ["province", nil], ["province_id", 2], ["question", "Whos' the biggest dog in the world"], ["updated_at", Tue, 14 May 2013 17:10:25 UTC +00:00], ["user_id", 53]]
SQL (0.4ms) INSERT INTO "categorizations" ("category_id", "created_at", "question_id", "updated_at") VALUES (?, ?, ?, ?) [["category_id", 2], ["created_at", Tue, 14 May 2013 17:10:25 UTC +00:00], ["question_id", 66], ["updated_at", Tue, 14 May 2013 17:10:25 UTC +00:00]]
In the rails 4 app, after it processes the parameters in QuestionController#create, I'm getting this error in the server logs
Unpermitted parameters: category_ids
and the question is only getting inserted into the questions table
(0.2ms) BEGIN
SQL (67.6ms) INSERT INTO "questions" ("city", "created_at", "province_id", "question_content", "question_details", "updated_at", "user_id") VALUES ($1, $2, $3, $4, $5, $6, $7) RETURNING "id" [["city", "dd"], ["created_at", Tue, 14 May 2013 17:17:53 UTC +00:00], ["province_id", 3], ["question_content", "How's your car?"], ["question_details", "is it runnign"], ["updated_at", Tue, 14 May 2013 17:17:53 UTC +00:00], ["user_id", 12]]
(31.9ms) COMMIT
Although I am not storing the category_ids on the Questions model, I set category_ids as a permitted parameter in the questions_controller
def question_params
params.require(:question).permit(:question_details, :question_content, :user_id, :accepted_answer_id, :province_id, :city, :category_ids)
end
Can anyone explain how I'm supposed to save the category_ids? Note, there is no create action in the categories_controller.rb of either app.
These are the three tables that are the same in both apps
create_table "questions", force: true do |t|
t.text "question_details"
t.string "question_content"
t.integer "user_id"
t.integer "accepted_answer_id"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "province_id"
t.string "city"
end
create_table "categories", force: true do |t|
t.string "name"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "categorizations", force: true do |t|
t.integer "category_id"
t.integer "question_id"
t.datetime "created_at"
t.datetime "updated_at"
end
Update
This is the create action from the Rails 3 app
def create
@question = Question.new(params[:question])
respond_to do |format|
if @question.save
format.html { redirect_to @question, notice: 'Question was successfully created.' }
format.json { render json: @question, status: :created, location: @question }
else
format.html { render action: "new" }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
This is the create action from the Rails 4 app
def create
@question = Question.new(question_params)
respond_to do |format|
if @question.save
format.html { redirect_to @question, notice: 'Question was successfully created.' }
format.json { render json: @question, status: :created, location: @question }
else
format.html { render action: "new" }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
This is the question_params method
private
def question_params
params.require(:question).permit(:question_details, :question_content, :user_id, :accepted_answer_id, :province_id, :city, :category_ids)
end
This https://github.com/rails/strong_parameters seems like the relevant section of the docs:
The permitted scalar types are String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile and Rack::Test::UploadedFile.
To declare that the value in params must be an array of permitted scalar values map the key to an empty array:
params.permit(:id => [])
In my app, the category_ids are passed to the create action in an array
"category_ids"=>["", "2"],
Therefore, when declaring strong parameters, I explicitly set category_ids to be an array
params.require(:question).permit(:question_details, :question_content, :user_id, :accepted_answer_id, :province_id, :city, :category_ids => [])
Works perfectly now!
(IMPORTANT: As @Lenart notes in the comments, the array declarations must be at the end of the attributes list, otherwise you'll get a syntax error.)