What can prevent an attribute from being created in rails? - ruby-on-rails

Question

Everything doesn't seem to be too hard but I've spent hours yet still can't get it working.
If I do Category.create(:name => "foo") in the rails console, a new category with its name gets created beautifully.
(0.2ms) begin transaction
SQL (0.3ms) INSERT INTO "categories" ("created_at", "name", "updated_at") VALUES (?, ?, ?) [["created_at", "2014-09-16 15:40:01.218700"], ["name", "foo"], ["updated_at", "2014-09-16 15:40:01.218700"]]
(14.5ms) commit transaction
=> #<Category id: 38, created_at: "2014-09-16 15:40:01", updated_at: "2014-09-16 15:40:01", name: "foo">
However, if I do it on the pages something goes wrong. My Category model has only one attribute which is "name", and I want all of them to be listed on my category index page.
<% #categories.each do |category| %>
<ul>
<li>
<b><%= category.name %></b><br />
<% category.products.each do |product| %>
<%= product.title %><br />
<% end %>
</li>
</ul>
<% end %>
<%= link_to "Create new category", categories_new_path %>
If I create a new category with its name in the console, it appears on the page with its name with no problem. But if I create it on the page, there's a category created with its name attribute being "nil". So please help me figure out where the problem is. I'm quite new to rails.
Here's my categories_controller.erb
class CategoriesController < ApplicationController
# load_and_authorize_resource
def new
#category = Category.new
end
def create
#category = Category.new(params[:name])
if #category.save
redirect_to categories_path
else
render 'new'
end
end
def index
#categories = Category.all
end
end
And here's my new.html.erb
<h1>New Category</h1>
<%= form_for(#category) do |f| %>
<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
<%= link_to 'Back', categories_path %>
Here's what appears in the server after I hit the submit button.
Started POST "/categories?locale=en" for 127.0.0.1 at 2014-09-17 00:02:42 +0800
Processing by CategoriesController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"ZdXcC/uEMA/jhGoGhYvp4lSHHfi/tmlm3CovJcYizJ0=", "category"=>{"name"=>"fwefewfw"}, "commit"=>"Create Category", "locale"=>"en"}
(0.1ms) begin transaction
SQL (0.2ms) INSERT INTO "categories" ("created_at", "updated_at") VALUES (?, ?) [["created_at", "2014-09-16 16:02:42.806041"], ["updated_at", "2014-09-16 16:02:42.806041"]]
(21.2ms) commit transaction
Note that there's no "name" being inserted in the sql statement.
I sense I missed something that is very basic. Well forgive me for being a newbie and thank you for the help!!

Answer 1

Looking at your tags, i think you are using rails 4 so you need to permit your attributes first. You can do it by this:
class CategoriesController < ApplicationController
# load_and_authorize_resource
def create
#category = Category.new(category_params)
if #category.save
redirect_to categories_path
else
render 'new'
end
end
private
def category_params
params.require(:category).permit(:name)
end
end
For details checkout Strong Parameters in Rails

Answer 2

It should be:
#category = Category.new(params[:category])
If you're on Rails 4, you should use the strong params and add the following method to your controller:
def category_params
params.require(:category).permit(:name)
end
And then change the Category.new line to:
#category = Category.new(category_params)
That's the new "safe" way to accept user-generated data in Rails models, and works really well once you get used to it.