mongoid-multitenancy

mongoid-multitenancy adds the ability to scope Mongoid models to a tenant in a shared database strategy. Tenants are represented by a tenant model, such as Client. mongoid-multitenancy will help you set the current tenant on each request and ensures that all 'tenant models' are always properly scoped to the current tenant: when viewing, searching and creating.

It is directly inspired by the acts_as_tenant gem for Active Record.

In addition, mongoid-multitenancy:

• allows you to set the current tenant
• allows shared items between the tenants
• allows you to define an immutable tenant field once it is persisted
• is thread safe
• redefines some mongoid functions like index, validates_with and delete_all to take in account the multitenancy.

Installation

Add this line to your application's Gemfile:

gem 'mongoid-multitenancy'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mongoid-multitenancy

Usage

There are two steps to add multi-tenancy to your app with mongoid-multitenancy:

1. setting the current tenant and
2. scoping your models.

Setting the current tenant

There are two ways to set the current tenant: (1) by setting the current tenant manually, or (2) by setting the current tenant for a block.

Setting the current tenant in a controller, manually

Mongoid::Multitenancy.current_tenant = client_instance

Setting the current_tenant yourself requires you to use a before_filter to set the Mongoid::Multitenancy.current_tenant variable.

Setting the current tenant for a block

Mongoid::Multitenancy.with_tenant(client_instance) do
  # Current tenant is set for all code in this block
end

This approach is useful when running background processes for a specified tenant. For example, by putting this in your worker's run method, any code in this block will be scoped to the current tenant. All methods that set the current tenant are thread safe.

Note: If the current tenant is not set by one of these methods, mongoid-multitenancy will apply a global scope to your models, not related to any tenant. So make sure you use one of the two methods to tell mongoid-multitenancy about the current tenant.

Scoping your models

class Client
  include Mongoid::Document

  field :name, :type => String
  validates_uniqueness_of :name
end

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant(:client)

  field :title, :type => String
end

Adding tenant to your model declaration will scope that model to the current tenant BUT ONLY if a current tenant has been set. The association passed to the tenant function must be valid.

tenant accepts several options:

Option	Default	Description
:optional	false	set to true when the tenant is optional
:immutable	true	set to true when the tenant field is immutable
:full_indexes	true	set to true to add the tenant field automatically to all the indexes
:index	false	set to true to define an index for the tenant field
:scopes	true	set to true to define scopes :shared and :unshared
:class_name, etc.		all the other options will be passed to the mongoid relation (belongs_to)

Some examples to illustrate this behavior:

 # This manually sets the current tenant for testing purposes. In your app this is handled by the gem.
Mongoid::Multitenancy.current_tenant = Client.find_by(:name => 'Perfect Memory') # => <#Client _id:50ca04b86c82bfc125000025, :name: "Perfect Memory">

 # All searches are scoped by the tenant, the following searches will only return objects belonging to the current client.
Article.all # => all articles where client_id => 50ca04b86c82bfc125000025

 # New objects are scoped to the current tenant
article = Article.new(:title => 'New blog')
article.save # => <#Article _id: 50ca04b86c82bfc125000044, title: 'New blog', client_id: 50ca04b86c82bfc125000025>

 # It can make the tenant field immutable once it is persisted to avoid inconsistency
article.persisted? # => true
article.client = another_client
article.valid? # => false

Optional tenant

When setting an optional tenant, for example to allow shared instances between all the tenants, the default scope will return both the tenant and the free-tenant items. That means that using Article.delete_all or Article.destroy_all will remove the shared items too.

Note: if a current tenant is set and you want to mark the item shared, you must explicitly set the tenant relation to nil after the initialization.

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant(:client, optional: true)

  field :title, :type => String
end

Mongoid::Multitenancy.with_tenant(client_instance) do
  Article.all # => all articles where client_id.in [50ca04b86c82bfc125000025, nil]
  article = Article.new(:title => 'New article')
  article.save # => <#Article _id: 50ca04b86c82bfc125000044, title: 'New blog', client_id: 50ca04b86c82bfc125000025>

  # tenant needs to be set manually to nil
  article = Article.new(:title => 'New article', :client => nil)
  article.save # => <#Article _id: 50ca04b86c82bfc125000044, title: 'New blog', client_id: 50ca04b86c82bfc125000025>
  article.tenant = nil
  article.save => <#Article _id: 50ca04b86c82bfc125000044, title: 'New blog', client_id: nil>
end

Rails

If you are using Rails, you may want to set the current tenant at each request.

Manually set the current tenant in ApplicationController using the host request

class ApplicationController < ActionController::Base
  before_filter :set_current_client

  def set_current_client
    current_client = Client.find_by_host(request.host)
    Mongoid::Multitenancy.current_tenant = current_client
  end
end

Setting the current_tenant yourself requires you to use a before_filter to set the Mongoid::Multitenancy.current_tenant variable.

Mongoid Uniqueness validators

mongoid-multitenancy brings a TenantUniqueness validator that will, depending on the tenant options, check that your uniqueness constraints are respected:

• When used with a mandatory tenant, the uniqueness constraint is scoped to the current client.

In the following case, 2 articles can have the same slug if they belongs to 2 different clients.

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant :client

  field :slug

  validates_tenant_uniqueness_of :slug
end

• When used with an optional tenant, the uniqueness constraint by default is not scoped if the item is shared, but is scoped to the client new item otherwise. Note that by default in that case a private item cannot have a value if a shared item already uses it. You can change that behaviour by setting the option exclude_shared to true.

In the following case, 2 private articles can have the same slug if they belongs to 2 different clients. But if a shared article has the slug "slugA", no client will be able to use that slug again, like a standard validates_uniqueness_of does.

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant :client, optional: true

  field :slug

  validates_tenant_uniqueness_of :slug
end

In the following case, 2 private articles can have the same slug if they belongs to 2 different clients even if a shared article already uses that same slug, like a validates_uniqueness_of scope: :client does.

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant :client, optional: true

  field :slug

  validates_tenant_uniqueness_of :slug, exclude_shared: true
end

Mongoid indexes

mongoid-multitenancy automatically adds the tenant foreign key in all your mongoid indexes to avoid to redefine all your validators. If you prefer to define manually the indexes, you can use the option full_indexes: false.

To create a single index on the tenant field, you can use the option index: true like any belongs_to declaration (false by default)

On the example below, only one indexe will be created:

• { 'title_id' => 1, 'client_id' => 1 }

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant :client, full_indexes: true

  field :title

  index({ :title => 1 })
end

On the example below, 2 indexes will be created:

• { 'client_id' => 1 }
• { 'title_id' => 1 }

class Article
  include Mongoid::Document
  include Mongoid::Multitenancy::Document

  tenant :client, index: true

  field :title

  index({ :title => 1 })
end

Author & Credits

mongoid-multitenancy is written by Aymeric Brisse, from Perfect Memory.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request