Fix initialization crash when no DB connection (#177)

Author: NeverovDS

lib/actual_db_schema/engine.rb

@@ -15,21 +15,50 @@ class Engine < ::Rails::Engine
 
     initializer "actual_db_schema.schema_dump_exclusions" do
       ActiveSupport.on_load(:active_record) do
-        table_name = ActualDbSchema::Store::DbAdapter::TABLE_NAME
+        apply_schema_dump_exclusions
+      end
+    end
+
+    def self.apply_schema_dump_exclusions
+      table_name = ActualDbSchema::Store::DbAdapter::TABLE_NAME
+      ignore_schema_dump_table(table_name)
+      return unless schema_dump_flags_supported?
+      return unless schema_dump_connection_available?
+
+      apply_structure_dump_flags(table_name)
+    end
+
+    class << self
+      private
+
+      def ignore_schema_dump_table(table_name)
+        return unless defined?(ActiveRecord::SchemaDumper)
+        return unless ActiveRecord::SchemaDumper.respond_to?(:ignore_tables)
+
+        ActiveRecord::SchemaDumper.ignore_tables |= [table_name]
+      end
+
+      def schema_dump_flags_supported?
+        defined?(ActiveRecord::Tasks::DatabaseTasks) &&
+          ActiveRecord::Tasks::DatabaseTasks.respond_to?(:structure_dump_flags)
+      end
 
-        if defined?(ActiveRecord::SchemaDumper) && ActiveRecord::SchemaDumper.respond_to?(:ignore_tables)
-          ActiveRecord::SchemaDumper.ignore_tables |= [table_name]
+      # Avoid touching db config unless we explicitly use DB storage
+      # or a connection is already available.
+      def schema_dump_connection_available?
+        has_connection = begin
+          ActiveRecord::Base.connection_pool.connected?
+        rescue ActiveRecord::ConnectionNotDefined, ActiveRecord::ConnectionNotEstablished
+          false
         end
 
-        next unless defined?(ActiveRecord::Tasks::DatabaseTasks)
-        next unless ActiveRecord::Tasks::DatabaseTasks.respond_to?(:structure_dump_flags)
+        ActualDbSchema.config[:migrations_storage] == :db || has_connection
+      end
 
+      def apply_structure_dump_flags(table_name)
         flags = Array(ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags)
         adapter = ActualDbSchema.db_config[:adapter].to_s
-        database = ActualDbSchema.db_config[:database]
-        if database.nil? && ActiveRecord::Base.respond_to?(:connection_db_config)
-          database = ActiveRecord::Base.connection_db_config&.database
-        end
+        database = database_name
 
         if adapter.match?(/postgres/i)
           flag = "--exclude-table=#{table_name}*"
@@ -41,6 +70,14 @@ class Engine < ::Rails::Engine
 
         ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = flags
       end
+
+      def database_name
+        database = ActualDbSchema.db_config[:database]
+        if database.nil? && ActiveRecord::Base.respond_to?(:connection_db_config)
+          database = ActiveRecord::Base.connection_db_config&.database
+        end
+        database
+      end
     end
   end
 end

test/rake_task_db_storage_full_test.rb

@@ -110,7 +110,6 @@ def down
               TestingState.down << :ts360
             end
           end
-          TS360 = Ts360 unless defined?(TS360)
         RUBY
       end
 
@@ -175,7 +174,6 @@ def down
   after do
     utils.clear_db_storage_table
     ActualDbSchema.config[:migrations_storage] = :file
-    utils.reset_acronyms
   end
 
   describe "db:rollback_branches:manual" do

test/support/test_utils.rb

@@ -136,6 +136,7 @@ def prepare_phantom_migrations(db_config = nil)
   end
 
   def cleanup(db_config = nil)
+    reset_acronyms
     if db_config
       db_config.each do |name, c|
         ActiveRecord::Base.establish_connection(**c)