Rails - collection_select is converting output to a string instead of an integer (and not saving)

Question

I am having a problem with my collection_select in rails and I can't seem to find what's causing it. I have 3 models, users, projects and budgets.

Users can have multiple projects, and projects can have one budget. Each budget has one project.

I created a collection_select field to display a list of the possible budgets for users to select, which is working fine, except that for some reason, its converting the budget 'id' (an integer) into a string before saving it as an integer in the 'budget_id' field in my 'projects' table. I can't figure out why its doing this! Any help would be greatly appreciated!

Code as follows:

Extract from the terminal when I submit a new project form (which displays correctly). As far as I can see, it's correctly selecting the id of the budget item selected, but it's somehow converted it from an integer to a string which is why it won't save?:

Started POST "/projects" for ::1 at 2016-08-23 22:24:10 +0200
Processing by ProjectsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"DCY3kFtDVDguJUqznBDuJcXEZBqbsxz3Q1bCxNngkPIaccAFpl43vKD9308cOLlZboVcjvDu2FTTmLwI+9ERdw==", "project"=>{"description"=>"this is a test"}, "Project"=>{"budget_id"=>"4"}, "commit"=>"Create Project"}
User Load (0.4ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT $2  [["id", 1], ["LIMIT", 1]]
(0.1ms)  BEGIN
SQL (0.5ms)  INSERT INTO "projects" ("description", "created_at", "updated_at", "user_id") VALUES ($1, $2, $3, $4) RETURNING "id"  [["description", "this is a test"], ["created_at", 2016-08-23 20:24:10 UTC], ["updated_at", 2016-08-23 20:24:10 UTC], ["user_id", 1]]
(5.8ms)  COMMIT
Redirected to http://localhost:3000/projects/27
Completed 302 Found in 16ms (ActiveRecord: 6.8ms)

Here is the schema for the budgets, users and projects tables:

create_table "budgets", force: :cascade do |t|
  t.string   "name"
  t.integer  "minimum"
  t.integer  "maximum"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
end

create_table "projects", force: :cascade do |t|
  t.string   "description"
  t.datetime "created_at",  null: false
  t.datetime "updated_at",  null: false
  t.integer  "user_id"
  t.integer  "budget_id"
  t.index ["user_id"], name: "index_projects_on_user_id", using: :btree
end

create_table "users", force: :cascade do |t|
  t.string   "email",                  default: "", null: false
  t.string   "encrypted_password",     default: "", null: false
  t.string   "reset_password_token"
  t.datetime "reset_password_sent_at"
  t.datetime "remember_created_at"
  t.integer  "sign_in_count",          default: 0,  null: false
  t.datetime "current_sign_in_at"
  t.datetime "last_sign_in_at"
  t.inet     "current_sign_in_ip"
  t.inet     "last_sign_in_ip"
  t.datetime "created_at",                          null: false
  t.datetime "updated_at",                          null: false
  t.string   "first_name"
  t.string   "last_name"
  t.string   "phone"
  t.index ["email"], name: "index_users_on_email", unique: true, using: :btree
  t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree
end

Extract from projects controller

def new
  @project = current_user.projects.new
  @budgets = Budget.all
end

def create
  @project = current_user.projects.new(project_params)
    if @project.save!
      redirect_to @project, notice: 'Project was successfully created.'
    else
      render :new
    end
end

def project_params
  params.require(:project).permit(:user_id, :description, :budget_id)
end

Extract from the _form view for the new project

<div class="field">
  <%= f.label :budget %>
  <%= collection_select(:Project, :budget_id, @budgets, :id, :list_of_budgets) %>
  </div>

Projects model

class Project < ApplicationRecord
  belongs_to :user
  has_one :budget
end

Budgets model

class Budget < ApplicationRecord
  belongs_to :project


 def list_of_budgets
    "#{name} (#{minimum} to #{maximum})"
  end 


end

I'm at a loss! Thanks for any help!

Answer 1

Form parameters always submit as strings - rails will handle that.

Your issue is that you've used :Project instead of :project so the value ends up as params[:Project][:budget_id] instead of params[:project][:budget_id].