Reworked things to:

1) maintain separation between "common" and tenant schemas
   (means that "common" tables are not also in the tenant schema!)
2) taks to process all tenants or a single tenant
3) support for per tenant migrations (potentially scary)
4) changed default so that db:migrate does NOT run
   apartment migrations.

lib/apartment.rb

@@ -10,7 +10,7 @@ class << self
 
     extend Forwardable
 
-    ACCESSOR_METHODS  = [:use_schemas, :seed_after_create, :prepend_environment, :append_environment]
+    ACCESSOR_METHODS  = [:use_schemas, :seed_after_create, :prepend_environment, :append_environment, :migration_path]
     WRITER_METHODS    = [:tenant_names, :database_schema_file, :excluded_models, :default_schema, :persistent_schemas, :connection_class, :tld_length, :db_migrate_tenants]
 
     attr_accessor(*ACCESSOR_METHODS)
@@ -33,7 +33,7 @@ def tenant_names
     def db_migrate_tenants
       return @db_migrate_tenants if defined?(@db_migrate_tenants)
 
-      @db_migrate_tenants = true
+      @db_migrate_tenants = false
     end
 
     # Default to empty array

lib/apartment/adapters/abstract_adapter.rb

@@ -65,9 +65,9 @@ def drop(tenant)
       #
       #   @param {String?} tenant Database or schema to connect to
       #
-      def process(tenant = nil)
+      def process(tenant = nil, exclusive = false)
         previous_tenant = current_tenant
-        switch(tenant)
+        switch(tenant, exclusive)
         yield if block_given?
 
       ensure
@@ -93,11 +93,11 @@ def reset
       #
       #   @param {String} tenant Database name
       #
-      def switch(tenant = nil)
+      def switch(tenant = nil, exclusive = false)
         # Just connect to default db and return
         return reset if tenant.nil?
 
-        connect_to_new(tenant).tap do
+        connect_to_new(tenant, exclusive).tap do
           ActiveRecord::Base.connection.clear_query_cache
         end
       end
@@ -126,7 +126,7 @@ def create_tenant(tenant)
       #
       #   @param {String} tenant Database name
       #
-      def connect_to_new(tenant)
+      def connect_to_new(tenant, exclusive = false)
         Apartment.establish_connection multi_tenantify(tenant)
         Apartment.connection.active?   # call active? to manually check if this connection is valid
 

lib/apartment/adapters/postgresql_adapter.rb

@@ -49,6 +49,22 @@ def drop(tenant)
         raise SchemaNotFound, "The schema #{tenant.inspect} cannot be found."
       end
 
+      def load(tenant)
+        # require 'active_record/schema_dumper'
+        # filename = File.join(Apartment.migration_path, "#{tenant}_schema.rb")
+        # File.open(filename, "w:utf-8") do |file|
+        #   ActiveRecord::SchemaDumper.dump(ActiveRecord::Base.connection, file)
+        # end
+      end
+
+      def dump(tenant)
+        require 'active_record/schema_dumper'
+        filename = File.join(Apartment.migration_path, "..", "#{tenant}_schema.rb")
+        File.open(filename, "w:utf-8") do |file|
+          ActiveRecord::SchemaDumper.dump(ActiveRecord::Base.connection, file)
+        end
+      end
+
       #   Reset search path to default search_path
       #   Set the table_name to always use the default namespace for excluded models
       #
@@ -84,12 +100,16 @@ def current_tenant
 
       #   Set schema search path to new schema
       #
-      def connect_to_new(tenant = nil)
+      def connect_to_new(tenant = nil, exclusive = false)
         return reset if tenant.nil?
         raise ActiveRecord::StatementInvalid.new("Could not find schema #{tenant}") unless Apartment.connection.schema_exists? tenant
 
         @current_tenant = tenant.to_s
-        Apartment.connection.schema_search_path = full_search_path
+        if exclusive
+          Apartment.connection.schema_search_path = @current_tenant
+        else
+          Apartment.connection.schema_search_path = full_search_path
+        end
 
       rescue *rescuable_exceptions
         raise SchemaNotFound, "One of the following schema(s) is invalid: #{tenant}, #{full_search_path}"
@@ -113,7 +133,7 @@ def full_search_path
       end
 
       def persistent_schemas
-        [@current_tenant, Apartment.persistent_schemas].flatten
+        [@current_tenant, Apartment.persistent_schemas].flatten.uniq
       end
     end
   end

lib/apartment/database.rb

@@ -8,7 +8,7 @@ module Database
     extend self
     extend Forwardable
 
-    def_delegators :adapter, :create, :current_tenant, :current, :current_database, :drop, :process, :process_excluded_models, :reset, :seed, :switch
+    def_delegators :adapter, :create, :current_tenant, :current, :current_database, :drop, :process, :process_excluded_models, :reset, :seed, :switch, :dump, :load
 
     attr_writer :config
 

lib/apartment/migrator.rb

@@ -7,27 +7,39 @@ module Migrator
 
     # Migrate to latest
     def migrate(database)
-      Database.process(database) do
+      Database.process(database, true) do
         version = ENV["VERSION"] ? ENV["VERSION"].to_i : nil
 
-        ActiveRecord::Migrator.migrate(ActiveRecord::Migrator.migrations_paths, version) do |migration|
+        ActiveRecord::Migrator.migrate(migration_paths(database), version) do |migration|
           ENV["SCOPE"].blank? || (ENV["SCOPE"] == migration.scope)
         end
+        Database.dump(database)
       end
     end
 
     # Migrate up/down to a specific version
     def run(direction, database, version)
-      Database.process(database) do
-        ActiveRecord::Migrator.run(direction, ActiveRecord::Migrator.migrations_paths, version)
+      Database.process(database, true) do
+        ActiveRecord::Migrator.run(direction, migration_paths(database), version)
+        Database.dump(database)
       end
     end
 
     # rollback latest migration `step` number of times
     def rollback(database, step = 1)
-      Database.process(database) do
-        ActiveRecord::Migrator.rollback(ActiveRecord::Migrator.migrations_paths, step)
+      Database.process(database, true) do
+        ActiveRecord::Migrator.rollback(migration_paths(database), step)
+        Database.dump(database)
       end
     end
+
+    private
+
+    def migration_paths(tenant)
+      paths = [Apartment.migration_path]
+      paths << "#{Apartment.migration_path}/../#{tenant}" if File.exists?("#{Apartment.migration_path}/../#{tenant}")
+      paths
+    end
+
   end
 end

lib/apartment/railtie.rb

@@ -11,16 +11,16 @@ class Railtie < Rails::Railtie
     #
     config.before_initialize do
       Apartment.configure do |config|
+        config.db_migrate_tenants = false
         config.excluded_models = []
         config.use_schemas = true
         config.tenant_names = []
         config.seed_after_create = false
         config.prepend_environment = false
         config.append_environment = false
         config.tld_length = 1
+        config.migration_path = "#{Rails.root}/db/apartment/migrate"
       end
-
-      ActiveRecord::Migrator.migrations_paths = Rails.application.paths['db/migrate'].to_a
     end
 
     #   Hook into ActionDispatch::Reloader to ensure Apartment is properly initialized

lib/generators/apartment/install/templates/apartment.rb

@@ -9,6 +9,11 @@
 #
 Apartment.configure do |config|
 
+  # Determines whether db:migrations will automatically
+  # run apartment migrations or not. Defautls to false
+  #
+  # config.db_migrate_tenants = true
+
   # These models will not be multi-tenanted,
   # but remain in the global (public) namespace
   #
@@ -43,7 +48,3 @@
 # Rails.application.config.middleware.use 'Apartment::Elevators::Domain'
 
 Rails.application.config.middleware.use 'Apartment::Elevators::Subdomain'
-
-##
-# Rake enhancements so that db:migrate etc... also runs migrations on all tenants
-require 'apartment/tasks/enhancements'

lib/tasks/apartment.rake

@@ -2,8 +2,10 @@ require 'apartment/migrator'
 
 apartment_namespace = namespace :apartment do
 
+  task :init => ['environment', 'db:load_config']
+
   desc "Create all tenants"
-  task create: 'db:migrate' do
+  task create: :init do
     tenants.each do |tenant|
       begin
         puts("Creating #{tenant} tenant")
@@ -15,8 +17,8 @@ apartment_namespace = namespace :apartment do
   end
 
   desc "Migrate all tenants"
-  task :migrate do
-    warn_if_tenants_empty
+  task migrate: :init do
+    err_if_tenants_empty
 
     tenants.each do |tenant|
       begin
@@ -29,8 +31,8 @@ apartment_namespace = namespace :apartment do
   end
 
   desc "Seed all tenants"
-  task :seed do
-    warn_if_tenants_empty
+  task seed: :init do
+    err_if_tenants_empty
 
     tenants.each do |tenant|
       begin
@@ -45,8 +47,8 @@ apartment_namespace = namespace :apartment do
   end
 
   desc "Rolls the migration back to the previous version (specify steps w/ STEP=n) across all tenants."
-  task :rollback do
-    warn_if_tenants_empty
+  task rollback: :init do
+    err_if_tenants_empty
 
     step = ENV['STEP'] ? ENV['STEP'].to_i : 1
 
@@ -60,10 +62,75 @@ apartment_namespace = namespace :apartment do
     end
   end
 
+  namespace :tenant do
+    desc "Migrate a single tenant: required paramter TENANT=name"
+    task :migrate,[:tenant] => :init do |t, args|
+      tenant = args.tenant || ENV['TENANT']
+
+      err_if_tenants_empty
+      raise 'TENANT is required' unless tenant
+      raise "TENANT #{tenant} is unknown" if !tenants.include?(tenant)
+
+      begin
+        puts("Migrating #{tenant} tenant")
+        Apartment::Migrator.migrate tenant 
+      rescue Apartment::TenantNotFound => e
+        puts e.message
+      end
+    end
+
+    desc "Rolls the migration back to the previous version (specify steps w/ STEP=n) for one TENANT."
+    task :rollback,[:tenant, :step] => :init do |t, args|
+      tenant = args.tenant || ENV['TENANT']
+      step = args.step || ENV['STEP'] ? ENV['STEP'].to_i : 1
+
+      err_if_tenants_empty
+      raise 'TENANT is required' unless tenant
+      raise "TENANT #{tenant} is unknown" if !tenants.include?(tenant)
+
+      begin
+        puts("Rolling back #{tenant} tenant")
+        Apartment::Migrator.rollback tenant, step
+      rescue Apartment::TenantNotFound => e
+        puts e.message
+      end
+    end
+
+    desc 'Create a db/schema.rb file that can be portably used against any DB supported by AR'
+    task :dump, [:tenant] => ['environment', 'db:load_config'] do |t, args|
+
+      tenant = args.tenant || ENV['TENANT']
+
+      err_if_tenants_empty
+      raise 'TENANT is required' unless tenant
+      raise "TENANT #{tenant} is unknown" if !tenants.include?(tenant)
+
+      Apartment::Database.dump(tenant)
+
+      # apartment_namespace['dump'].reenable
+    end
+
+    # desc 'Load a schema.rb file into the database'
+    # task :load,[:tenant] => ['environment', 'db:load_config'] do |t, args|
+    #   tenant = args.tenant || ENV['TENANT']
+
+    #   err_if_tenants_empty
+    #   raise 'TENANT is required' unless tenant
+    #   raise "TENANT #{tenant} is unknown" if !tenants.include?(tenant)
+
+    #   puts "apartment:tenant:load(#{tenant})"
+
+    #   Apartment::Database.load(tenant)
+    # end
+
+  end
+
+
   namespace :migrate do
+
     desc 'Runs the "up" for a given migration VERSION across all tenants.'
-    task :up do
-      warn_if_tenants_empty
+    task up: :init do
+      err_if_tenants_empty
 
       version = ENV['VERSION'] ? ENV['VERSION'].to_i : nil
       raise 'VERSION is required' unless version
@@ -79,8 +146,8 @@ apartment_namespace = namespace :apartment do
     end
 
     desc 'Runs the "down" for a given migration VERSION across all tenants.'
-    task :down do
-      warn_if_tenants_empty
+    task down: :init do
+      err_if_tenants_empty
 
       version = ENV['VERSION'] ? ENV['VERSION'].to_i : nil
       raise 'VERSION is required' unless version
@@ -96,7 +163,7 @@ apartment_namespace = namespace :apartment do
     end
 
     desc  'Rolls back the tenant one migration and re migrate up (options: STEP=x, VERSION=x).'
-    task :redo do
+    task redo: :init do
       if ENV['VERSION']
         apartment_namespace['migrate:down'].invoke
         apartment_namespace['migrate:up'].invoke
@@ -111,17 +178,7 @@ apartment_namespace = namespace :apartment do
     ENV['DB'] ? ENV['DB'].split(',').map { |s| s.strip } : Apartment.tenant_names || []
   end
 
-  def warn_if_tenants_empty
-    if tenants.empty?
-      puts <<-WARNING
-        [WARNING] - The list of tenants to migrate appears to be empty. This could mean a few things:
-
-          1. You may not have created any, in which case you can ignore this message
-          2. You've run `apartment:migrate` directly without loading the Rails environment
-            * `apartment:migrate` is now deprecated. Tenants will automatically be migrated with `db:migrate`
-
-        Note that your tenants currently haven't been migrated. You'll need to run `db:migrate` to rectify this.
-      WARNING
-    end
+  def err_if_tenants_empty
+    raise "tenants is empty" if tenants.empty?
   end
 end