Rename view

CHANGELOG.md

@@ -5,6 +5,13 @@ changelog, see the [commits] for each version via the version links.
 
 [commits]: https://github.com/scenic-views/scenic/commits/master
 
+## next
+
+### Added
+
+- `rename_view` allow to rename a view. Generators have been updated to
+  accept a `--rename` option.
+
 ## [1.5.4] - September 16, 2020
 
 [1.5.4]: https://github.com/scenic-views/scenic/compare/v1.5.3...v1.5.4

README.md

@@ -195,6 +195,68 @@ you would need to refresh view B first, then right after refresh view A. If you
 would like this cascading refresh of materialized views, set `cascade: true`
 when you refresh your materialized view.
 
+## I made a mistake and I need to rename a view?
+
+Run the view generator as following:
+
+```sh
+$ rails generate scenic:view results --rename search_results
+      create  db/views/results_v01.sql
+      create  db/migrate/[TIMESTAMP]_update_results_to_version_2.rb
+```
+
+Now, `db/views/results_v01.sql` sould be identical to 
+`db/views/search_results_v01.sql`, you will need to edit this file if you rename
+another views in this migration that is in this definition, so just rename it
+too accordingly ;-)
+The migration should look something like this:
+
+```ruby
+class UpdateResultsToVersion2 < ActiveRecord::Migration
+  def change
+    rename_view :search_results, :results,
+      version: 2,
+      revert_to_version: 1
+  end
+end
+```
+
+## Need to change a materialized view without downtime?
+
+Before using `replace_view` on materialized views, you need to create and
+populate the next version of the view in a previous release. So you will have
+to follow these steps:
+
+1. Create a new materialized view
+   `rails generate scenic:view table_name_next --materialized --no-data`
+   that will take improvement of your future view `table_name`, you can 
+   copy-paste the content of the last version of `table_name` as a starter.
+2. Deploy and apply this migration
+3. Refresh the view within a task or in the Rails console
+   `Scenic.database.refresh_materialized_view(:table_name_nexts, concurrently: false)`
+4. Use that view by removing the previous and renaming the next one in a single
+   migration 
+   `rails generate scenic:view table_name --materialized --rename table_name_next`
+   and edit the migration to change `rename_view` by `replace_view`:
+   ```ruby
+   def change
+     replace_view :table_name_nexts, :table_names,
+       version: 1,
+       revert_to_version: 1,
+       materialized: true
+   end
+   ```
+
+`replace_view` will internaly do:
+1. store indexes of `table_names`
+2. remove `table_names`
+3. rename `table_names_next` to `table_names`
+4. ensure that the definition on the database is the same as the one in 
+   `db/views` folder
+5. rename indexes by replacing `table_names_next` by `table_names` in 
+   their names
+6. applied valid stored indexes on the new version of `table_names`
+
 ## I don't need this view anymore. Make it go away.
 
 Scenic gives you `drop_view` too:

lib/generators/scenic/view/USAGE

@@ -7,6 +7,7 @@ Description:
 
   To create a materialized view, pass the '--materialized' option.
   To create a materialized view with NO DATA, pass '--no-data' option.
+  To rename a view, pass '--rename actual_view_name' option.
 
 Examples:
     rails generate scenic:view searches

lib/generators/scenic/view/templates/db/migrate/create_view.erb

@@ -1,5 +1,5 @@
 class <%= migration_class_name %> < <%= activerecord_migration_class %>
   def change
-    create_view <%= formatted_plural_name %><%= create_view_options %>
+    create_view <%= format_view_name(plural_name) %><%= create_view_options %>
   end
 end

lib/generators/scenic/view/templates/db/migrate/update_view.erb

@@ -1,12 +1,14 @@
 class <%= migration_class_name %> < <%= activerecord_migration_class %>
   def change
+  <%- if renaming? -%>
+    rename_view <%= format_view_name(previous_plural_name) %>, <%= format_view_name(plural_name) %>,
+  <%- else -%>
+    update_view <%= format_view_name(plural_name) %>,
+  <%- end -%>
+      version: <%= definition.version %>,
+      revert_to_version: <%= previous_definition.version %><%- if materialized? -%>,<%- end -%>
   <%- if materialized? -%>
-    update_view <%= formatted_plural_name %>,
-      version: <%= version %>,
-      revert_to_version: <%= previous_version %>,
       materialized: <%= no_data? ? "{ no_data: true }" : true %>
-  <%- else -%>
-    update_view <%= formatted_plural_name %>, version: <%= version %>, revert_to_version: <%= previous_version %>
   <%- end -%>
   end
 end

lib/generators/scenic/view/view_generator.rb

@@ -1,6 +1,8 @@
 require "rails/generators"
 require "rails/generators/active_record"
 require "generators/scenic/materializable"
+require "scenic/definition"
+require "scenic/definitions"
 
 module Scenic
   module Generators
@@ -10,17 +12,23 @@ class ViewGenerator < Rails::Generators::NamedBase
       include Scenic::Generators::Materializable
       source_root File.expand_path("templates", __dir__)
 
+      class_option :rename,
+        type: :string,
+        required: false,
+        banner: "PREVIOUS_VIEW_NAME",
+        desc: "rename from previous view name"
+
       def create_views_directory
-        unless views_directory_path.exist?
-          empty_directory(views_directory_path)
+        unless Scenic.configuration.definitions_path.exist?
+          empty_directory(Scenic.configuration.definitions_path)
         end
       end
 
       def create_view_definition
         if creating_new_view?
           create_file definition.path
         else
-          copy_file previous_definition.full_path, definition.full_path
+          copy_file previous_definition.path, definition.path
         end
       end
 
@@ -31,6 +39,7 @@ def create_migration_file
             "db/migrate/create_#{plural_file_name}.rb",
           )
         else
+          version = definition.version
           migration_template(
             "db/migrate/update_view.erb",
             "db/migrate/update_#{plural_file_name}_to_version_#{version}.rb",
@@ -43,22 +52,11 @@ def self.next_migration_number(dir)
       end
 
       no_tasks do
-        def previous_version
-          @previous_version ||=
-            Dir.entries(views_directory_path)
-              .map { |name| version_regex.match(name).try(:[], "version").to_i }
-              .max
-        end
-
-        def version
-          @version ||= destroying? ? previous_version : previous_version.next
-        end
-
         def migration_class_name
           if creating_new_view?
             "Create#{class_name.tr('.', '').pluralize}"
           else
-            "Update#{class_name.pluralize}ToVersion#{version}"
+            "Update#{class_name.pluralize}ToVersion#{definition.version}"
           end
         end
 
@@ -79,36 +77,57 @@ def file_name
         super.tr(".", "_")
       end
 
-      def views_directory_path
-        @views_directory_path ||= Rails.root.join("db", "views")
+      def previous_file_name
+        (options[:rename] || singular_name).tr(".", "_")
+      end
+
+      def previous_plural_name
+        (options[:rename] || singular_name).pluralize
       end
 
-      def version_regex
-        /\A#{plural_file_name}_v(?<version>\d+)\.sql\z/
+      def previous_plural_file_name
+        previous_file_name.pluralize
+      end
+
+      def definitions
+        @definitions ||= Scenic::Definitions.new(
+          plural_file_name,
+        )
+      end
+
+      def previous_definitions
+        @previous_definitions ||= Scenic::Definitions.new(
+          previous_plural_file_name,
+        )
       end
 
       def creating_new_view?
-        previous_version.zero?
+        previous_definitions.none?
       end
 
       def definition
-        Scenic::Definition.new(plural_file_name, version)
+        @definition ||= Scenic::Definition.new(
+          plural_file_name,
+          (definitions.max.try(:version) || 0)
+            .public_send(destroying? ? :itself : :next),
+        )
       end
 
       def previous_definition
-        Scenic::Definition.new(plural_file_name, previous_version)
+        @previous_definition ||= previous_definitions.max ||
+          Scenic::Definition.new(previous_plural_file_name, 0)
       end
 
       def destroying?
         behavior == :revoke
       end
 
-      def formatted_plural_name
-        if plural_name.include?(".")
-          "\"#{plural_name}\""
-        else
-          ":#{plural_name}"
-        end
+      def renaming?
+        options[:rename]
+      end
+
+      def format_view_name(name)
+        name.include?(".") ? "\"#{name}\"" : ":#{name}"
       end
 
       def create_view_options
@@ -120,7 +139,7 @@ def create_view_options
       end
 
       def destroying_initial_view?
-        destroying? && version == 1
+        destroying? && definition.version == 1
       end
     end
   end

lib/scenic.rb

@@ -1,7 +1,6 @@
 require "scenic/configuration"
 require "scenic/adapters/postgres"
 require "scenic/command_recorder"
-require "scenic/definition"
 require "scenic/railtie"
 require "scenic/schema_dumper"
 require "scenic/statements"