[Resolves #27] Added before hook to connected to to try to set the te…

…nant

- Monkeypatch `connected_to` rails active record method to try to ensure that whenever we switch connection we connect to the proper tenant

- Removed `allow_prepend_tenant_name` configuration because we ran into concurrency issues. When the connection goes back to the pool its attributes are set with the old values and we were getting queries being made to the wrong tenant. I still think that using this prepend_tenant seems like a good idea but I'll need further testing and investigation on how to make it safe. There is a bug reported in the original apartment gem that seems to report similar issues (influitive/apartment#186)

README.md

@@ -341,28 +341,6 @@ Rails will always access the 'public' tenant when accessing these models, but no
 
 ### Postgresql Schemas
 
-#### Allow prepend tenant name
-
-`config.allow_prepend_tenant_name` currently defaults to `false`.
-
-This configuration only applies while using postgres adapter and `config.use_schemas` is set to `true`.
-This is also intended to be used in combination with `Apartment::Model` module. What this module
-does is to overwrite the `arel_table` method, used internally by Rails to create the arel_table
-object and build the final SQL query to include the apartment's current tenant schema name.
-This becomes particularly helpful when we have read/write replicas in our rails application and
-we need to switch the connection between read and write DB.
-When in our application we run `SomeModel.connected_to(role: :reading)` this will switch the connection but also reset the schema that it is pointing to.
-
-The alternative to this is whenever you switch the connection manually, ensure that you switch to
-the expected schema as well. E.g.
-
-```ruby
-ActiveRecord::Base.connected_to(role: :reading) do
-  Apartment::Tenant.switch!(your_schema)
-  do_your_logic
-end
-```
-
 #### Alternative: Creating new schemas by using raw SQL dumps
 
 Apartment can be forced to use raw SQL dumps insted of `schema.rb` for creating new schemas. Use this when you are using some extra features in postgres that can't be represented in `schema.rb`, like materialized views etc.

lib/apartment.rb

@@ -6,7 +6,9 @@
 require 'active_record'
 require 'apartment/tenant'
 
-require_relative 'apartment/arel/visitors/postgresql'
+# require_relative 'apartment/arel/visitors/postgresql'
+
+require_relative 'apartment/active_record/connection_handling' if ActiveRecord.version.release >= Gem::Version.new('6.0')
 
 if ActiveRecord.version.release >= Gem::Version.new('6.1')
   require_relative 'apartment/active_record/schema_migration'
@@ -18,8 +20,7 @@ class << self
     extend Forwardable
 
     ACCESSOR_METHODS = %i[use_schemas use_sql seed_after_create prepend_environment
-                          append_environment with_multi_server_setup
-                          allow_prepend_tenant_name].freeze
+                          append_environment with_multi_server_setup].freeze
 
     WRITER_METHODS = %i[tenant_names database_schema_file excluded_models
                         default_schema persistent_schemas connection_class

lib/apartment/active_record/connection_handling.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module ConnectionHandling
+    def connected_to_with_tenant(database: nil, role: nil, prevent_writes: false, &blk)
+      current_tenant = Apartment::Tenant.current
+
+      connected_to_without_tenant(database: database, role: role, prevent_writes: prevent_writes) do
+        Apartment::Tenant.switch!(current_tenant)
+        yield(blk)
+      end
+    end
+
+    alias connected_to_without_tenant connected_to
+    alias connected_to connected_to_with_tenant
+  end
+end

lib/apartment/railtie.rb

@@ -18,7 +18,6 @@ class Railtie < Rails::Railtie
         config.seed_after_create = false
         config.prepend_environment = false
         config.append_environment = false
-        config.allow_prepend_tenant_name = false
       end
 
       ActiveRecord::Migrator.migrations_paths = Rails.application.paths['db/migrate'].to_a

spec/adapters/jdbc_postgresql_adapter_spec.rb

@@ -20,27 +20,6 @@ def tenant_names
 
       it_should_behave_like 'a generic apartment adapter'
       it_should_behave_like 'a schema based apartment adapter'
-
-      context 'using allow_prepend_tenant_name' do
-        let(:api) { Apartment::Tenant }
-
-        before do
-          Apartment.allow_prepend_tenant_name = true
-          api.create(db1)
-          api.create(db2)
-        end
-
-        it 'prepends the tenant schema name to the table name when building the query' do
-          Apartment::Tenant.switch!(db1)
-          sql = "SELECT \"users\".* FROM \"#{db1}\".\"users\" LIMIT 10"
-          # NOTE: for some reason there is an extra space in the output of to_sql
-          expect(UserWithTenantModel.all.limit(10).to_sql.gsub(/\s+/, ' ')).to eq(sql)
-
-          Apartment::Tenant.switch!(db2)
-          sql = "SELECT \"users\".* FROM \"#{db2}\".\"users\" LIMIT 10"
-          expect(UserWithTenantModel.all.limit(10).to_sql.gsub(/\s+/, ' ')).to eq(sql)
-        end
-      end
     end
 
     context 'using databases' do

spec/adapters/postgresql_adapter_spec.rb

@@ -20,27 +20,6 @@ def tenant_names
 
       it_should_behave_like 'a generic apartment adapter'
       it_should_behave_like 'a schema based apartment adapter'
-
-      context 'using allow_prepend_tenant_name' do
-        let(:api) { Apartment::Tenant }
-
-        before do
-          Apartment.allow_prepend_tenant_name = true
-          api.create(db1)
-          api.create(db2)
-        end
-
-        it 'prepends the tenant schema name to the table name when building the query' do
-          Apartment::Tenant.switch!(db1)
-          sql = "SELECT \"users\".* FROM \"#{db1}\".\"users\" LIMIT 10"
-          # NOTE: for some reason there is an extra space in the output of to_sql
-          expect(UserWithTenantModel.all.limit(10).to_sql.gsub(/\s+/, ' ')).to eq(sql)
-
-          Apartment::Tenant.switch!(db2)
-          sql = "SELECT \"users\".* FROM \"#{db2}\".\"users\" LIMIT 10"
-          expect(UserWithTenantModel.all.limit(10).to_sql.gsub(/\s+/, ' ')).to eq(sql)
-        end
-      end
     end
 
     context 'using schemas with SQL dump' do

spec/unit/config_spec.rb

@@ -35,14 +35,6 @@ def tenant_names_from_array(names)
       expect(Apartment.use_schemas).to be false
     end
 
-    it 'should set allow_prepend_tenant_name' do
-      Apartment.configure do |config|
-        config.excluded_models = []
-        config.allow_prepend_tenant_name = true
-      end
-      expect(Apartment.allow_prepend_tenant_name).to be true
-    end
-
     it 'should set seed_data_file' do
       Apartment.configure do |config|
         config.seed_data_file = seed_data_file_path