Add database tasks to help with dumping DB

lib/tasks/db.rake

@@ -0,0 +1,132 @@
+# Source: https://gist.github.com/amit/45e750edde94b70431f5d42caadee423
+namespace :db do
+
+    desc "Dumps the database to backups"
+    task :dump => :environment do
+
+        dump_fmt = 'p'      # 'c' or 'p', 't', 'd'
+        dump_sfx = suffix_for_format dump_fmt
+        backup_dir = backup_directory true
+        cmd = nil
+        with_config do |app, host, db, user, passw|
+            file_name = Time.now.strftime("%Y%m%d%H%M%S") + "_" + db + '.' + dump_sfx
+            # puts "app = #{app}"
+            # puts "host = #{host}"
+            # puts "db = #{db}"
+            # puts "user = #{user}"
+            # puts "Password = #{passw}"
+            cmd = "PGPASSWORD=#{passw}  pg_dump -F #{dump_fmt} -v -U #{user} -h #{host} -d #{db} -f #{backup_dir}/#{file_name}"
+        end
+        puts cmd
+        exec cmd
+    end
+
+    desc "Writes forum posts to CSV"
+    task :csv => :environment do
+        require "csv"
+
+        file_name = Time.now.strftime("%Y%m%d%H%M%S") + "_posts.csv"
+
+        CSV.open(file_name, "wb") do |csv|
+            headers = [:id, :author, :topic, :topic_id, :body, :created_at]
+            csv << headers
+
+            Post.includes(:author, :topic).in_batches do |batch|
+                batch.each do |post|
+                    csv << [
+                        post.id,
+                        post.author.username,
+                        post.topic.title,
+                        post.topic_id,
+                        post.body,
+                        post.created_at
+                    ]
+                end
+            end
+        end
+
+        puts "Created CSV export at #{file_name}"
+    end
+
+    desc "Show the existing database backups"
+    task :list => :environment do
+        backup_dir = backup_directory
+        puts "#{backup_dir}"
+        exec "/bin/ls -lt #{backup_dir}"
+    end
+
+    desc "Restores the database from a backup using PATTERN"
+    task :restore, [:pat] => :environment do |task,args|
+        if args.pat.present?
+            cmd = nil
+            with_config do |app, host, db, user, passwd|
+                backup_dir = backup_directory
+                files = Dir.glob("#{backup_dir}/*#{args.pat}*")
+                case files.size
+                when 0
+                  puts "No backups found for the pattern '#{args.pat}'"
+                when 1
+                  file = files.first
+                  fmt = format_for_file file
+                  if fmt.nil?
+                    puts "No recognized dump file suffix: #{file}"
+                  else
+                    cmd = "pg_restore -F #{fmt} -v -c -C #{file}"
+                  end
+                else
+                  puts "Too many files match the pattern '#{args.pat}':"
+                  puts ' ' + files.join("\n ")
+                  puts "Try a more specific pattern"
+                end
+            end
+            unless cmd.nil?
+              Rake::Task["db:drop"].invoke
+              Rake::Task["db:create"].invoke
+              puts cmd
+              exec cmd
+            end
+        else
+            puts 'Please pass a pattern to the task'
+        end
+    end
+
+    private
+
+    def suffix_for_format suffix
+        case suffix
+        when 'c' then 'dump'
+        when 'p' then 'sql'
+        when 't' then 'tar'
+        when 'd' then 'dir'
+        else nil
+        end
+    end
+
+    def format_for_file file
+        case file
+        when /\.dump$/ then 'c'
+        when /\.sql$/  then 'p'
+        when /\.dir$/  then 'd'
+        when /\.tar$/  then 't'
+        else nil
+        end
+    end
+
+    def backup_directory create=false
+        backup_dir = "#{Rails.root}/db/backups"
+        if create and not Dir.exists?(backup_dir)
+          puts "Creating #{backup_dir} .."
+          Dir.mkdir(backup_dir)
+        end
+        backup_dir
+    end
+
+    def with_config
+        yield Rails.application.class.module_parent_name.underscore,
+          ActiveRecord::Base.connection_db_config.host,
+          ActiveRecord::Base.connection_db_config.database,
+          ActiveRecord::Base.connection_db_config.configuration_hash[:username],
+          ActiveRecord::Base.connection_db_config.configuration_hash[:password]
+    end
+
+end