Use route-level multitenancy

Multitenancy is not a far-fetched concept, and you might need it when you reach a certain level with your app. Avo is ready to handle that.

This guide will show you one way of achieving that, but if can be changed if you have different needs.

Prepare the Current model

We will use Rails' Current model to hold the account.

# app/models/current.rb
class Current < ActiveSupport::CurrentAttributes
  attribute :account
end

Add middleware to catch the account param

We're trying to fetch the account number from the params and see if we have an account with that ID in this middleware. If so, store it in the Current.account model, where we can use it throughout the app.

## Multitenant Account Middleware
#
# Included in the Rails engine if enabled.
#
# Used for setting the Account by the first ID in the URL like Basecamp 3.
# This means we don't have to include the Account ID in every URL helper.
# From JumpstartRails AccountMiddleware

class AccountMiddleware
  def initialize(app)
    @app = app
  end

  # http://example.com/12345/projects
  def call(env)
    request = ActionDispatch::Request.new env
    # Fetch the account id from the path
    _, account_id, request_path = request.path.split("/", 3)

    # Check if the id is a number
    if /\d+/.match?(account_id)
      # See if that account is present in the database.
      if (account = Account.find_by(id: account_id))
        # If the account is present, set the Current.account to that
        Current.account = account
      else
        # If not, redirect to the root path
        return [302, {"Location" => "/"}, []]
      end

      request.script_name = "/#{account_id}"
      request.path_info = "/#{request_path}"
    end

    @app.call(request.env)
  end
end

Update the custom tools routes

By default, when generating custom tools, we're adding them to the parent app's routes. Because we're declaring them there, the link helpers don't hold the account id in the params.

Rails.application.routes.draw do
  scope :avo do
    get "custom_page", to: "avo/tools#custom_page"
  end

  devise_for :users

  # Your routes

  authenticate :user, -> user { user.admin? } do
    mount Avo::Engine => Avo.configuration.root_path
  end
end

To fix that, we need to move them as if they were added to Avo's routes.

# config/routes.rb
Rails.application.routes.draw do
  devise_for :users

  # Your routes

  authenticate :user, -> user { user.admin? } do
    mount Avo::Engine => Avo.configuration.root_path
  end
end

# Move Avo custom tools routes to Avo engine
if defined? ::Avo
  Avo::Engine.routes.draw do
    # make sure you don't add the `avo/` prefix to the controller below
    get 'custom_page', to: "tools#custom_page"
  end
end

# app/controllers/avo/tools_controller.rb
class Avo::ToolsController < Avo::ApplicationController
  def custom_page
    @page_title = "Your custom page"

    add_breadcrumb "Your custom page"
  end
end

Retrieve and use the account

Throughout your app you can use Current.account or if you add it to Avo's context object and use it from there.

# config/initializers/avo.rb
Avo.configure do |config|
  config.set_context do
    {
      foo: 'bar',
      user: current_user,
      params: request.params,
      account: Current.account
    }
  end
end

Check out this PR for how to update an app to support multitenancy.