#382 Tagging

Do we have XSS vulnerability because of displaying 'raw tags.map'? Hacker could inject some sort of malicious code in a tag name so it would be sent to user without escaping.

Thanks Ryan. I've been working on a some simple tagging with the native Postgres string-array type this week, it seems to work very well although I don't have any comparative data on performance yet.

https://github.com/dockyard/postgres_ext was a huge help for getting started with it.

Shouldn't the assignment of self.tags in the method tag_names= be moved to an after_save callback method? What if the validations on a newly created article fail? The tags would still be created without proper referencing.

Assuming that a tag should only be created once (unique constraint on name) I'd rather use:

self.tags = names.split(",").map do |n|
  Tag.find_or_create_by_name(n.strip)
end

instead of

self.tags = names.split(",").map do |n|
  Tag.where(name: n.strip).first_or_create!
end

For better performance one should also consider a counter cache on the belongs_to :tags in the taggings model. This would avoid the join when calculating the tag counts in:

def self.tag_counts
  Tag.select("tags.*, count(taggings.tag_id) as count").
    joins(:taggings).group("taggings.tag_id")
end

I implemented my own tagging system similar to the code you wrote a while back, but I noticed that it did not scale well. If you only have a few tags it works fine, but if you have hundreds of thousands or millions and similar numbers of articles then performance degrades substantially. I ended up having to do quite a bit of caching to get acceptable performance, especially for the tag cloud.

I did not use, or know about, the acts_as_taggable_on gem at the time. Does anybody know how well it scales? If not I will definitely be running some performance tests on it this week.

Such an awesome episode. Though to get this example to work, I had to adjust the syntax from line 2 of your routes.rb example from:

puts "get 'tags/:tag', to: 'articles#index', as: :tag"

to

puts "get 'tags/:tag' => 'articles#index', :as => :tag"

You probably want to replace

max = tags.sort_by(&:count).last

with

max = tags.max_by(&:count)

There's no need to sort the array only to pick the largest element.

article.tags.map(&:name).map { |t| link_to t, tag_path(t) }.join(', ')

should really be

article.tags.map { |t| link_to t.name, tag_path(t.name) }.join(', ')

The original code will produce unnecessary iterations that might start to affect performance once the number of tags increases. In general: Keep iterations to a minimum – in my experience, it's the number one performance problem of most Rails apps.

What if I want to query for articles that belong to multiple tags?

I tried this method:

Article.joins(:tags).where(:tags => { :name => ["foo", "bar"] } )

but this returns me every post that has either tag foo, or bar or both.

How do I search only for posts that have both foo and bar at the same time?

To complete the full circle, it would be great to see how to use tags with http://aehlke.github.com/tag-it/

There is only one thing that the gem covers in the example and the solution made from scratch doesn't cover: the relation for the tagging to belong to a user (act_as_tagger in the user model). How do you think this might be done, as most user authentication solutions (like Devise, Authlogic or Sorcery) doesn't provide the current_user helper in the ActiveRecord layer.

I haven't touched RoR in a month and getting rusty, took a small break came back to computer and it hit me, the problem was with a haml conversion from html:

WRONG WAY

#tag_cloud
  = tag_cloud Post.tag_counts, %w[css1 css2 css3 css4] do |tag, css_class|
    = link_to tag.name, tag_path(tag.name), class: css_class

RIGHT WAY

#tag_cloud
  - tag_cloud Post.tag_counts, %w[css1 css2 css3 css4] do |tag, css_class|
    = link_to tag.name, tag_path(tag.name), class: css_class

Can delete my questions to clean up this railscast =)

Any ideas how to overwrite the to_param method? Overwriting it in /app/models/tag.rb just doesn't work in urls, though it works in console when invokung Tag.first.to_param

What i mean is instead of urls like /tags/foo%20bar i would like to have urls like /tags/foo-bar

the tag_cloud from scratch isn't working here. Is it may be because I'm using postgresql as a database?

Hello! Thanks for gem. But I have problem: on editing model with tags, I have empty tags field. I tried both ways of realising but also empty.

<%= form_for(@post) do |f| %>
...
    <div class="field">
      <%= f.label :tag_list, "Tags (separated by commas)" %><br />
      <%= f.text_field :tag_list %>
    </div>
...
<% end %>

I tried to print simple @post.tag_list, an it is not empty but in form it is empty( Need help.

Awesome! With the help of this and http://railscasts.com/episodes/17-habtm-checkboxes-revised I was able to integrate this to work the way I wanted. Thanks Ryan.

Was noticing that this was not doing anything to standardize the capitalizations so therefore tagname and Tagname are two different things in this implementation, in order to fix this I simply used a before_save to titleize the names with this:

before_save :titleize

def titleize
  self.name = self.name.titleize
end

Pretty simple but assigning of the name threw me for a loop for a minute. Great cast!

Here are the necessary model methods for any DataMapper users:

has n, :taggings
has n, :tags, :through => :taggings

def self.tagged_with(name)
  Tag.all(name: name).articles
end

def tag_list
  tags.map(&:name).join(", ")
end

def self.tag_counts
  DataMapper.repository.adapter.select('select tags.*, t.count from tags inner join (select taggings.tag_id, count(taggings.tag_id) as count from taggings group by taggings.tag_id) t where tags.id = t.tag_id')
end

def tag_list=(names)
  self.tags = names.split(',').map do |n|
    Tag.first_or_create(name: n.strip)
  end
end

Hope that helps.

When trying to tag an article, lets say "chemistry, sept 20/2012" as in want to organize all the articles posted on a certain date.
How do you rewrite the routes.rb:
get 'tags/:tag', to: 'articles#index', as: :tag
in order to access tag names that embed "/" forward slash?!
I get this error when I try to access sept 20/2012:
No route matches [GET] "/tags/sept%2020/2012"

Hello. I have a problem. This app use sqlite3, but i need postgresql. I edit my Gemfile and database.yml. My app work in rails server, but on heroku doesn't. May be it's needs to edit something other. Write me please, what i needs to edit to use postgersql.

Hello there,

This episode is great and helpful,but what if I need additional fields for storing like tag description? Any idea?

What would it look like to add two tags to an existing or new article at the rails command line?
Thanks!

Hi there,

I'm having an issue. So far I installed it and run the migrations :

gem 'acts-as-taggable-on', '2.4.1'

rails g acts_as_taggable_on:migration
rake db:migrate

But then as soon as I add this line :

acts_as_taggable

into my model, I've got the following error :
wrong number of arguments (3 for 1..2)

I'm using Ruby 2.0.0-p247 and Rails4.0.0.beta1 (The project is already pretty big and we can't dare to update the Rails version).

Anyone already faced the same issue?

Thanks a lot

Trying to follow this tutorial with Rails 4 but getting a 'RuntimeError' when trying to insert the tags_list into the view.

Do I need to change anything for Rails 4? Do I need to do anything with the 'attr_accessible' method, as this is moved for Rails 4?

Great episode, as usual.

Is there any way to make this work for multi-word tags?

My index page works fine with one-word tags (e.g. 'superman', 'comic', etc.), but when I have a multi-word tag (e.g. 'the riddler', 'the penguin', etc.) I get the following error:

undefined method 'joins' for []:Array.

When I try to filter my articles by the tag 'Tag 3', the URL that I am directed to is:

http://localhost:3000/tags/Tag%203

I imagine it has something to do with this line:

<p>Tags: <%= raw @article.tag_list.map { |t| link_to t, tag_path(t) }.join(", ") %></p>

Anyone know how to make this work with multi-word tags?

How can I list specific tags in route file? I want to create a link and filter specific tags. I want to be able to link the path to specific filtered tags for my posts using link_to. e.g. <%= link_to "Blog", posts_path %>

puts "
  get 'tags/:tag', to: 'posts#index', as: :tag"

I am using Rails 4, and instead of: rails generate acts_as_taggable_on:migration,
I have to use: rake acts_as_taggable_on_engine:install:migrations.

But I want to remove this rake acts_as_taggable_on_engine:install:migrations that I did, but I can't find anywhere how to do this

I'm on rails4 ruby2.1 and I can't seem to get the tagging table to record the association. Any help will be much appreciated. (doing this from scratch)

# records.rb

has_many :taggings
has_many :tags, through: :taggings


def tag_list
  tags.map(&:name).join(", ")
end
  
def tag_list=(names)
  self.tags = names.split(",").map do |n|
    Tag.where(name: n.strip).first_or_create!
  end
end

# tagging.rb

belongs_to :record
belongs_to :tag

# tag.rb

has_many :taggings
has_many :records, through: :taggings

# views/records/_form.html.erb

<div class="field">
  <%= f.label :tag_list %><br />
  <%= f.text_field :tag_list %>
</div>

# records_controller.rb

def record_params
  params.require(:record).permit(:name, :tag_list)
end

The tags do get created in the tag table; but no association defined in the tagging table between the record and the tag.

When I got to the 2 minute mark, at the page refresh, I got the following error: 'undefined method write_inheritable_attribute' for #<Class:0x007fccb5cd1c50>. Additionally it points to line 1:

1: <%- model_class = Factoid -%>
2: <div class="page-header">
3:   <h1><%=t '.title', :default => [:'helpers.titles.edit', 'Edit %{model}'], :model => model_class.model_name.human.titleize %></h1>
4: </div>

The Model:

class Factoid < ActiveRecord::Base
  attr_accessible :description, :name, :title, :tag_list

  acts_as_taggable

  validates_presence_of :description, :name, :title
  validates_uniqueness_of :title


  UNRANSACKABLE_ATTRIBUTES = ["id", "updated_at"]

  def self.ransackable_attributes auth_object = nil
    (column_names - UNRANSACKABLE_ATTRIBUTES) + _ransackers.keys
  end

end

I succesfully implemented a tag cloud in Ruby, from scratch. Excellent tutorial!

Now I would like to make my tag cloud more dynamic, so that it allows you to narrow down listings.

On my photoblog, each photo has several tags. Once you click on a tag, say "Tokyo", all photos tagged with "Tokyo" are listed. I now want to add two things:
* I want the tag cloud to be updated and display only tags associated to the remaining photos, the "Tokyo" subset.
* When you click on a tag in this subset-tag cloud, say "2008", I want all photos to be listed that are tagged with "Tokyo" and "2008" (instead of all photos tagged with "2008").

I have been trying to implement this for days, no luck so far. I'm new to Ruby so any help will be much appreciated!

Why exactly is the tagging model necessary? It's being used kind of as a join table right, but for the simpler functionality it seems unnecessary. Is there something I'm missing?

Mind you: In rails 4 dont use attr_accessible in the model, instead in the controller add:

   private
    def post_params
      params.require(:post).permit(:title, :intro, :content, :user_id, :tag_list)
    end

ehh this took me an hour to figure out :)

ps: nice to add this in the modell though:

  validates :tag_list, presence: true

You have a wrong gem, the correct gem is:

gem 'foundation-rails'

And not:

    gem 'zurb-foundation'

Here is a reddit post that really helped me get this working:

http://www.reddit.com/r/rails/comments/2chtgw/tagging_in_rails_4/

Ai perfecta dreptate in ce priveste http://calculatoaresecondhand.xyz/ pentru aplicabilitatea pe sistemele refurbished

This episode covering tagging from scratch has been upgraded to Rails 5. Checkout Tagging from Scratch in Rails 5