[ruby-on-rails] Is there a way to get a collection of all the Models in your Rails app?

Is there a way that you can get a collection of all of the Models in your Rails app?

Basically, can I do the likes of: -

Models.each do |model|
  puts model.class.name
end

I'm just throwing this example here if anyone finds it useful. Solution is based on this answer https://stackoverflow.com/a/10712838/473040.

Let say you have a column public_uid that is used as a primary ID to outside world (you can findjreasons why you would want to do that here)

Now let say you've introduced this field on bunch of existing Models and now you want to regenerate all the records that are not yet set. You can do that like this

# lib/tasks/data_integirity.rake
namespace :di do
  namespace :public_uids do
    desc "Data Integrity: genereate public_uid for any model record that doesn't have value of public_uid"
    task generate: :environment do
      Rails.application.eager_load!
      ActiveRecord::Base
        .descendants
        .select {|f| f.attribute_names.include?("public_uid") }
        .each do |m| 
          m.where(public_uid: nil).each { |mi| puts "Generating public_uid for #{m}#id #{mi.id}"; mi.generate_public_uid; mi.save }
      end 
    end 
  end 
end

you can now run rake di:public_uids:generate

This worked for me. Special thanks to all the posts above. This should return a collection of all your models.

models = []

Dir.glob("#{Rails.root}/app/models/**/*.rb") do |model_path|
  temp = model_path.split(/\/models\//)
  models.push temp.last.gsub(/\.rb$/, '').camelize.constantize rescue nil
end

ActiveRecord::Base.connection.tables

Just in case anyone stumbles on this one, I've got another solution, not relying on dir reading or extending the Class class...

ActiveRecord::Base.send :subclasses

This will return an array of classes. So you can then do

ActiveRecord::Base.send(:subclasses).map(&:name)

Here's a solution that has been vetted with a complex Rails app (the one powering Square)

def all_models
  # must eager load all the classes...
  Dir.glob("#{RAILS_ROOT}/app/models/**/*.rb") do |model_path|
    begin
      require model_path
    rescue
      # ignore
    end
  end
  # simply return them
  ActiveRecord::Base.send(:subclasses)
end

It takes the best parts of the answers in this thread and combines them in the simplest and most thorough solution. This handle cases where your models are in subdirectories, use set_table_name etc.

The whole answer for Rails 3, 4 and 5 is:

If cache_classes is off (by default it's off in development, but on in production):

Rails.application.eager_load!

Then:

ActiveRecord::Base.descendants

This makes sure all models in your application, regardless of where they are, are loaded, and any gems you are using which provide models are also loaded.

This should also work on classes that inherit from ActiveRecord::Base, like ApplicationRecord in Rails 5, and return only that subtree of descendants:

ApplicationRecord.descendants

If you'd like to know more about how this is done, check out ActiveSupport::DescendantsTracker.

I looked for ways to do this and ended up choosing this way:

in the controller:
    @data_tables = ActiveRecord::Base.connection.tables

in the view:
  <% @data_tables.each do |dt|  %>
  <br>
  <%= dt %>
  <% end %>
  <br>

source: http://portfo.li/rails/348561-how-can-one-list-all-database-tables-from-one-project

ActiveRecord::Base.connection.tables.map do |model|
  model.capitalize.singularize.camelize
end

will return

["Article", "MenuItem", "Post", "ZebraStripePerson"]

Additional information If you want to call a method on the object name without model:string unknown method or variable errors use this

model.classify.constantize.attribute_names

Dir.foreach("#{Rails.root.to_s}/app/models") do |model_path|
  next unless model_path.match(/.rb$/)
  model_class = model_path.gsub(/.rb$/, '').classify.constantize
  puts model_class
end

This will give to you all the model classes you have on your project.

The Rails implements the method descendants, but models not necessarily ever inherits from ActiveRecord::Base, for example, the class that includes the module ActiveModel::Model will have the same behavior as a model, just doesn't will be linked to a table.

So complementing what says the colleagues above, the slightest effort would do this:

Monkey Patch of class Class of the Ruby:

class Class
  def extends? constant
    ancestors.include?(constant) if constant != self
  end
end

and the method models, including ancestors, as this:

The method Module.constants returns (superficially) a collection of symbols, instead of constants, so, the method Array#select can be substituted like this monkey patch of the Module:

class Module

  def demodulize
    splitted_trail = self.to_s.split("::")
    constant = splitted_trail.last

    const_get(constant) if defines?(constant)
  end
  private :demodulize

  def defines? constant, verbose=false
    splitted_trail = constant.split("::")
    trail_name = splitted_trail.first

    begin
      trail = const_get(trail_name) if Object.send(:const_defined?, trail_name)
      splitted_trail.slice(1, splitted_trail.length - 1).each do |constant_name|
        trail = trail.send(:const_defined?, constant_name) ? trail.const_get(constant_name) : nil
      end
      true if trail
    rescue Exception => e
      $stderr.puts "Exception recovered when trying to check if the constant \"#{constant}\" is defined: #{e}" if verbose
    end unless constant.empty?
  end

  def has_constants?
    true if constants.any?
  end

  def nestings counted=[], &block
    trail = self.to_s
    collected = []
    recursivityQueue = []

    constants.each do |const_name|
      const_name = const_name.to_s
      const_for_try = "#{trail}::#{const_name}"
      constant = const_for_try.constantize

      begin
        constant_sym = constant.to_s.to_sym
        if constant && !counted.include?(constant_sym)
          counted << constant_sym
          if (constant.is_a?(Module) || constant.is_a?(Class))
            value = block_given? ? block.call(constant) : constant
            collected << value if value

            recursivityQueue.push({
              constant: constant,
              counted: counted,
              block: block
            }) if constant.has_constants?
          end
        end
      rescue Exception
      end

    end

    recursivityQueue.each do |data|
      collected.concat data[:constant].nestings(data[:counted], &data[:block])
    end

    collected
  end

end

Monkey patch of String.

class String
  def constantize
    if Module.defines?(self)
      Module.const_get self
    else
      demodulized = self.split("::").last
      Module.const_get(demodulized) if Module.defines?(demodulized)
    end
  end
end

And, finally, the models method

def models
  # preload only models
  application.config.eager_load_paths = model_eager_load_paths
  application.eager_load!

  models = Module.nestings do |const|
    const if const.is_a?(Class) && const != ActiveRecord::SchemaMigration && (const.extends?(ActiveRecord::Base) || const.include?(ActiveModel::Model))
  end
end

private

  def application
    ::Rails.application
  end

  def model_eager_load_paths
    eager_load_paths = application.config.eager_load_paths.collect do |eager_load_path|
      model_paths = application.config.paths["app/models"].collect do |model_path|
        eager_load_path if Regexp.new("(#{model_path})$").match(eager_load_path)
      end
    end.flatten.compact
  end

I've tried so many of these answers unsuccessfully in Rails 4 (wow they changed a thing or two for god sakes) I decided to add my own. The ones that called ActiveRecord::Base.connection and pulled the table names worked but didn't get the result I wanted because I've hidden some models (in a folder inside of app/models/) that I didn't want to delete:

def list_models
  Dir.glob("#{Rails.root}/app/models/*.rb").map{|x| x.split("/").last.split(".").first.camelize}
end

I put that in an initializer and can call it from anywhere. Prevents unnecessary mouse-usage.

In just one line:

 ActiveRecord::Base.subclasses.map(&:name)

I think @hnovick's solution is a cool one if you dont have table-less models. This solution would work in development mode as well

My approach is subtly different though -

ActiveRecord::Base.connection.tables.map{|x|x.classify.safe_constantize}.compact

classify is well supposed to give you the name of the class from a string properly. safe_constantize ensures that you can turn it into a class safely without throwing an exception. This is needed in case you have database tables which are not models. compact so that any nils in the enumeration are removed.

For Rails5 models are now subclasses of ApplicationRecord so to get list of all models in your app you do:

ApplicationRecord.descendants.collect { |type| type.name }

Or shorter:

ApplicationRecord.descendants.collect(&:name)

If you are in dev mode, you will need to eager load models before:

Rails.application.eager_load!

To avoid pre-load all Rails, you can do this:

Dir.glob("#{Rails.root}/app/models/**/*.rb").each {|f| require_dependency(f) }

require_dependency(f) is the same that Rails.application.eager_load! uses. This should avoid already required file errors.

Then you can use all kind of solutions to list AR models, like ActiveRecord::Base.descendants

This works for Rails 3.2.18

Rails.application.eager_load!

def all_models
  models = Dir["#{Rails.root}/app/models/**/*.rb"].map do |m|
    m.chomp('.rb').camelize.split("::").last
  end
end

can check this

@models = ActiveRecord::Base.connection.tables.collect{|t| t.underscore.singularize.camelize}

Just came across this one, as I need to print all models with their attributes(built on @Aditya Sanghi's comment):

ActiveRecord::Base.connection.tables.map{|x|x.classify.safe_constantize}.compact.each{ |model| print "\n\n"+model.name; model.new.attributes.each{|a,b| print "\n#{a}"}}

I can't comment yet, but I think sj26 answer should be the top answer. Just a hint:

Rails.application.eager_load! unless Rails.configuration.cache_classes
ActiveRecord::Base.descendants

With Rails 6, Zetiwerk became the default code loader.

For eager loading, try:

Zeitwerk::Loader.eager_load_all

Then

ApplicationRecord.descendants

def load_models_in_development
  if Rails.env == "development"
    load_models_for(Rails.root)
    Rails.application.railties.engines.each do |r|
      load_models_for(r.root)
    end
  end
end

def load_models_for(root)
  Dir.glob("#{root}/app/models/**/*.rb") do |model_path|
    begin
      require model_path
    rescue
      # ignore
    end
  end
end

Module.constants.select { |c| (eval c).is_a?(Class) && (eval c) < ActiveRecord::Base }

Assuming all models are in app/models and you have grep & awk on your server (majority of the cases),

# extract lines that match specific string, and print 2nd word of each line
results = `grep -r "< ActiveRecord::Base" app/models/ | awk '{print $2}'`
model_names = results.split("\n")

It it faster than Rails.application.eager_load! or looping through each file with Dir.

EDIT:

The disadvantage of this method is that it misses models that indirectly inherit from ActiveRecord (e.g. FictionalBook < Book). The surest way is Rails.application.eager_load!; ActiveRecord::Base.descendants.map(&:name), even though it's kinda slow.

If you want just the Class names:

ActiveRecord::Base.descendants.map {|f| puts f}

Just run it in Rails console, nothing more. Good luck!

EDIT: @sj26 is right, you need to run this first before you can call descendants:

Rails.application.eager_load!

Yes there are many ways you can find all model names but what I did in my gem model_info is , it will give you all the models even included in the gems.

array=[], @model_array=[]
Rails.application.eager_load!
array=ActiveRecord::Base.descendants.collect{|x| x.to_s if x.table_exists?}.compact
array.each do |x|
  if  x.split('::').last.split('_').first != "HABTM"
    @model_array.push(x)
  end
  @model_array.delete('ActiveRecord::SchemaMigration')
end

then simply print this

@model_array

This seems to work for me:

  Dir.glob(RAILS_ROOT + '/app/models/*.rb').each { |file| require file }
  @models = Object.subclasses_of(ActiveRecord::Base)

Rails only loads models when they are used, so the Dir.glob line "requires" all the files in the models directory.

Once you have the models in an array, you can do what you were thinking (e.g. in view code):

<% @models.each do |v| %>
  <li><%= h v.to_s %></li>
<% end %>

On one line: Dir['app/models/\*.rb'].map {|f| File.basename(f, '.*').camelize.constantize }