Implement support for upgrades from older backups.

This is done by using a zip file as backup. This includes both the YAML
data and a schema.rb. When restoring, we create an empty database using
the schema.rb, import the data, and then run all the pending migrations.

Conflicts:
	app/models/backup.rb

app/controllers/backups_controller.rb

@@ -4,11 +4,13 @@ class BackupsController < AttachmentsController
 
   def create
     @backup = current_tenant.export
+    redirect_to current_tenant
   end
 
   def restore
     # TODO: access validation
     @backup = Backup.find(params[:id])
     @backup.import
+    redirect_to current_tenant
   end
 end

app/models/backup.rb

@@ -12,24 +12,70 @@ class Backup < Attachment
   #
   # Use this method for backup or migrations.
   def export
-    temp = Tempfile.open('export')
-    temp.binmode
+    dir = Dir.mktmpdir 'bookyt.backup'
+
+    data = Tempfile.new('data.yml', dir)
+    data.binmode
 
     old_level = ActiveRecord::Base.logger.level
     ActiveRecord::Base.logger.level = 2 # don't log debug or info
-    YamlDb::Helper.dumper.dump(temp)
+    YamlDb::Helper.dumper.dump(data)
     ActiveRecord::Base.logger.level = old_level
 
-    temp.close
-    title = "Backup %s.yaml" % DateTime.now.to_s(:db)
+    data.close
+
+    schema = Tempfile.new('schema.rb', dir)
+    schema.binmode
+
+    ActiveRecord::SchemaDumper.dump(ActiveRecord::Base.connection, schema)
+    schema.close
+
+    zip = Pathname.new(dir).join('backup-v1.zip')
+    Zip::File.open(zip, Zip::File::CREATE) do |zipfile|
+      zipfile.add('schema.rb', schema.path)
+      zipfile.add('data.yml', data.path)
+    end
 
-    self.file = temp
+    data.unlink
+    schema.unlink
+
+    title = "Backup %s" % DateTime.now.to_s(:db)
+
+    zip_file = File.new(zip, 'r')
+    # TODO: test if we can remove the directory before finishing reading
+    # a file it contains on Windows.
+    FileUtils.rmdir(dir)
+
+    self.file = zip_file
     self.title = title
   end
 
   # Import Data from YAML
   #
-  # This method loas a YAML file out of all the records in the database.
+  # This method restores a backup from a Backup record
+  # This record is normaly attached to a Tenant record.
+  #
+  # Use this method to restore.
+  def import
+    dir = Dir.mktmpdir 'bookyt.backup'
+    dirname = Pathname.new(dir)
+
+    Zip::File.open(file.current_path) do |zipfile|
+      schema = zipfile.glob('schema.rb').first
+      schema.extract(dirname.join('schema.rb'))
+      data = zipfile.glob('data.yml').first
+      data.extract(dirname.join('data.yml'))
+    end
+
+    load(dirname.join('schema.rb'))
+    ActiveRecord::Migrator.migrate(ActiveRecord::Migrator.migrations_paths, nil)
+
+    self.class.import_file(dirname.join('data.yml'))
+  end
+
+  # Import Data from a file
+  #
+  # This method loads a backup YAML file and creates records in the database.
   # This file is normaly attached to a Tenant record.
   #
   # Use this method for restore or migrations.

app/models/tenant.rb

@@ -94,7 +94,4 @@ def export
 
     backup
   end
-
-  def import
-  end
 end