Issue Adding Category to Article in Rails

Question

I have an issue adding Categories to article in my simple form. The categories are showing up in the simple_form_for but the category_id is not attributed to the article when creating it ! (params ?)

Tx for your help !

I have created two models

class Category < ApplicationRecord
  has_many :articles
end

class Article < ApplicationRecord
  belongs_to :category
  has_attachments :photos, maximum: 2
end

and a foreign key between them

create_table "articles", force: :cascade do |t|
  t.string   "title"
  t.text     "body"
  t.datetime "created_at",   null: false
  t.datetime "updated_at",   null: false
  t.string   "card_summary"
  t.text     "summary"
  t.integer  "category_id"
  t.index ["category_id"], name: "index_articles_on_category_id",      using: :btree
end

The Articles controller to create an article

def new
  @article = Article.new
end

def create
  @article = Article.new(article_params)
  if @article.save
    redirect_to article_path(@article)
  else
    render :new
  end
end

private

def article_params
  params.require(:article).permit(:title, :card_summary, :summary, :body, photos: [])
end

and the simple_form_for where I used f.association (which shows correctly the different categories)

<%= simple_form_for @article do |f| %>
  <%= f.input :title %>
  <%= f.input :card_summary %>
  <%= f.input :summary %>
  <%= f.input :photos, as: :attachinary %>
  <%= f.input :body %>
  <%= f.association :category %>

  <%= f.submit "Soumettre un article", class: "btn btn-primary" %>
<% end %>

I think my db is ok because I can attribute a category to an article with the console but I m stuck in this form. Any help would be much appreciated. Thx Edouard

EDIT

Here is my migration. Anything wrong?

class AddCategoryReferenceToArticles < ActiveRecord::Migration[5.0]
  def change
    add_reference :articles, :category, foreign_key: true, index: true
  end
end

Answer 1

Adding category_id in article_params should solve the issue

def article_params
  params.require(:article).permit(:title, :card_summary, :summary, :category_id, photos: [])
end