Mongoid Slug

Mongoid Slug generates a URL slug or permalink based on one or more fields in a Mongoid model. It sits idly on top of stringex, supporting non-Latin characters.

Installation

Add to your Gemfile:

gem 'mongoid-slug'

Usage

Set Up a Slug

class Book
  include Mongoid::Document
  include Mongoid::Slug

  field :title
  slug :title
end

Find a Document by its Slug

# GET /books/a-thousand-plateaus
book = Book.find params[:book_id]

Mongoid Slug will attempt to determine whether you want to find using the slugs field or the _id field by inspecting the supplied parameters.

Mongoid Slug will perform a find based on slugs only if all arguments passed to find are of the type String.
If your document uses BSON::ObjectId identifiers, and all arguments look like valid BSON::ObjectId, then Mongoid Slug will perform a find based on _id.
If your document uses any other type of identifiers, and all arguments passed to find are of the same type, then Mongoid Slug will perform a find based on _id.
If your document uses String identifiers and you want to be able find by slugs or ids, to get the correct behaviour, you should add a slug_id_strategy option to your _id field definition. This option should return something that responds to call (a callable) and takes one string argument, e.g. a lambda. This callable must return true if the string looks like one of your ids.

Book.fields['_id'].type
=> String
book = Book.find 'a-thousand-plateaus' # Finds by slugs
=> ...

class Post
  include Mongoid::Document
  include Mongoid::Slug

  field :_id, type: String, slug_id_strategy: lambda { |id| id.start_with?('...') }

  field :name
  slug  :name, history: true
end

Post.fields['_id'].type
=> String
post = Post.find 'a-thousand-plateaus' # Finds by slugs
=> ...
post = Post.find '50b1386a0482939864000001' # Finds by bson ids
=> ...

Examine slug.rb for all available options.

Updating Existing Records

To set slugs for existing records run following rake task:

rake mongoid_slug:set

You can pass model names as an option for which you want to set slugs:

rake mongoid_slug:set[Model1,Model2]

Nil Slugs

Empty slugs are possible and generate a nil value for the _slugs field. In the Post example above, a blank post name will cause the document record not to contain a _slugs field in the database. The default _slugs index is sparse, allowing that. If you wish to change this behavior add a custom validates_presence_of :_slugs validator to the document or change the database index to sparse: false.

Custom Slug Generation

By default Mongoid Slug generates slugs with stringex. If this is not desired you can define your own slug generator.

There are two ways to define slug generator.

Globally

Configure a block in config/initializers/mongoid_slug.rb as follows:

Mongoid::Slug.configure do |c|
  # create a block that takes the current object as an argument and return the slug
  c.slug = proc { |cur_obj|
    cur_object.slug_builder.to_url
  }
end

On Model

class Caption
  include Mongoid::Document
  include Mongoid::Slug

  # create a block that takes the current object as an argument and returns the slug
  slug do |cur_object|
    cur_object.slug_builder.to_url
  end
end

The to_url method comes from stringex.

You can define a slug builder globally and/or override it per model.

Scoping

To scope a slug by a reference association, pass :scope:

class Company
  include Mongoid::Document

  references_many :employees
end

class Employee
  include Mongoid::Document
  include Mongoid::Slug

  field :name
  referenced_in :company

  slug :name, scope: :company
end

In this example, if you create an employee without associating it with any company, the scope will fall back to the root employees collection.

Currently, if you have an irregular association name, you must specify the :inverse_of option on the other side of the assocation.

Embedded objects are automatically scoped by their parent.

Note that the unique index on the Employee collection in this example is derived from the scope value and is { _slugs: 1, company_id: 1}. Therefore :company must be referenced_in above the definition of slug or it will not be able to resolve the association and mistakenly create a { _slugs: 1, company: 1} index. An alternative is to scope to the field itself as follows:

class Employee
  include Mongoid::Document
  include Mongoid::Slug

  field :name
  field :company_id

  slug :name, scope: :company_id
end

Limit Slug Length

MongoDB has a default limit around 1KB to the size of the index keys and will raise error 17280, key too large to index when trying to create a record that causes an index key to exceed that limit. By default slugs are of the form text[-number] and the text portion is limited in size to Mongoid::Slug::MONGO_INDEX_KEY_LIMIT_BYTES - 32 bytes. You can change this limit with max_length or set it to nil if you're running MongoDB with failIndexKeyTooLong set to false.

class Company
  include Mongoid::Document
  include Mongoid::Slug

  field :name

  slug  :name, max_length: 24
end

Optionally Find and Create Slugs per Model Type

By default when using STI, the scope will be around the super-class.

class Book
  include Mongoid::Document
  include Mongoid::Slug
  field :title

  slug  :title, history: true
  embeds_many :subjects
  has_many :authors
end

class ComicBook < Book
end

book = Book.create(title: 'Anti Oedipus')
comic_book = ComicBook.create(title: 'Anti Oedipus')
comic_book.slugs.should_not eql(book.slugs)

If you want the scope to be around the subclass, then set the option by_model_type: true.

class Book
  include Mongoid::Document
  include Mongoid::Slug
  field :title

  slug  :title, history: true, by_model_type: true
  embeds_many :subjects
  has_many :authors
end

class ComicBook < Book
end

book = Book.create(title: 'Anti Oedipus')
comic_book = ComicBook.create(title: 'Anti Oedipus')
comic_book.slugs.should eql(book.slugs)

History

Enable slug history tracking by setting history: true.

class Page
  include Mongoid::Document
  include Mongoid::Slug

  field :title

  slug :title, history: true
end

The document will then be returned for any of the saved slugs:

page = Page.new title: "Home"
page.save
page.update_attributes title: "Welcome"

Page.find("welcome") == Page.find("home") # => true

Reserved Slugs

Pass words you do not want to be slugged using the reserve option:

class Friend
  include Mongoid::Document

  field :name
  slug :name, reserve: ['admin', 'root']
end

friend = Friend.create name: 'admin'
Friend.find('admin') # => nil
friend.slug # => 'admin-1'

When reserved words are not specified, the words 'new' and 'edit' are considered reserved by default. Specifying an array of custom reserved words will overwrite these defaults.

Localize Slugs

The slugs can be localized:

class PageSlugLocalize
  include Mongoid::Document
  include Mongoid::Slug

  field :title, localize: true
  slug  :title, localize: true
end

This feature is built upon Mongoid localized fields, so fallbacks and localization works as documented in the Mongoid manual.

Custom Find Strategies

By default find will search for the document by the id field if the provided id looks like a BSON::ObjectId, and it will otherwise find by the _slugs field. However, custom strategies can ovveride the default behavior, like e.g:

module Mongoid::Slug::UuidIdStrategy
  def self.call id
    id =~ /\A([0-9a-fA-F]){8}-(([0-9a-fA-F]){4}-){3}([0-9a-fA-F]){12}\z/
  end
end

Use a custom strategy by adding the slug_id_strategy annotation to the _id field:

class Entity
  include Mongoid::Document
  include Mongoid::Slug

  field :_id, type: String, slug_id_strategy: UuidIdStrategy

  field :user_edited_variation
  slug  :user_edited_variation, history: true
end

Adhoc Checking Whether a Slug is Unique

Lets say you want to have a auto-suggest function on your GUI that could provide a preview of what the url or slug could be before the form to create the record was submitted.

You can use the UniqueSlug class in your server side code to do this, e.g.

title = params[:title]
unique = Mongoid::Slug::UniqueSlug.new(Book.new).find_unique(title)
...
# return some representation of unique

Mongoid::Paranoia Support

The Mongoid::Paranoia gem adds "soft-destroy" functionality to Mongoid documents.

Mongoid::Slug contains special handling for Mongoid::Paranoia:

When destroying a paranoid document, the slug will be unset from the database.
When restoring a paranoid document, the slug will be rebuilt. Note that the new slug may not match the old one.
When resaving a destroyed paranoid document, the slug will remain unset in the database.
For indexing purposes, sparse unique indexes are used. The sparse condition will ignore any destroyed paranoid documents, since their slug is not set in database.

class Entity
  include Mongoid::Document
  include Mongoid::Slug
  include Mongoid::Paranoia
end

The following variants of Mongoid Paranoia are officially supported:

Mongoid 3 built-in Mongoid::Paranoia
Mongoid 4 or 5 gem http://github.com/simi/mongoid_paranoia

Contributing

Mongoid-slug is work of many of contributors. You're encouraged to submit pull requests, propose features, ask questions and discuss issues. See CONTRIBUTING for details.

onomated/mongoid-slug