Add support for ActiveRecord driver for ClickHouse

README.md

@@ -716,7 +716,7 @@ data_sources:
 
 ### ClickHouse
 
-Add [ClickHouse Ruby driver](https://github.com/shlima/click_house) to your Gemfile and set:
+Add [ClickHouse Ruby driver](https://github.com/shlima/click_house) OR [Clickhouse::Activerecord](https://github.com/PNixx/clickhouse-activerecord) to your Gemfile and set:
 ```yml
 data_sources:
   my_source:

lib/blazer/adapters/clickhouse_adapter.rb

@@ -1,14 +1,55 @@
 module Blazer
   module Adapters
     class ClickhouseAdapter < BaseAdapter
+      SUPPORTED_DRIVERS_MAPPING = {
+        "click_house" => ClickHouseDriver,
+        "clickhouse-activerecord" => ClickhouseActiverecordDriver
+      }.freeze
+
+      delegate :tables, to: :driver
+
+      # Wrapper for ClickHouse Ruby driver (https://github.com/shlima/click_house)
+      class ClickHouseDriver
+        delegate :tables, to: :connection
+
+        def initialize(config)
+          @config = ClickHouse::Config.new(**config)
+        end
+
+        def connection
+          @connection ||= ClickHouse::Connection.new(@config)
+        end
+
+        def execute(statement, format)
+          connection.post(query: { query: statement, default_format: format }).body
+        end
+      end
+
+      # Wrapper for Clickhouse::Activerecord driver (https://github.com/PNixx/clickhouse-activerecord)
+      class ClickhouseActiverecordDriver
+        delegate :tables, to: :connection
+
+        def initialize(config)
+          @config = config
+        end
+
+        def connection
+          @connection ||= ActiveRecord::Base.clickhouse_connection(@config)
+        end
+
+        def execute(statement, format)
+          body = connection.do_execute(statement, format: format)
+          format.in?(%w[CSV CSVWithNames]) ? CSV.parse(body) : body
+        end
+      end
+
       def run_statement(statement, _comment)
         columns = []
         rows = []
         error = nil
 
         begin
-          response = connection.post(query: { query: statement, default_format: "CSVWithNames" })
-          rows = response.body
+          rows = driver.execute(statement, "CSVWithNames")
           columns = rows.shift
         rescue => e
           error = e.message
@@ -17,54 +58,59 @@ def run_statement(statement, _comment)
         [columns, rows, error]
       end
 
-      def tables
-        connection.tables
-      end
-
       def schema
         statement = <<-SQL
           SELECT table, name, type
           FROM system.columns
-          WHERE database = '#{connection.config.database}'
+          WHERE database = '#{config[:database]}'
           ORDER BY table, position
         SQL
 
-        response = connection.post(query: { query: statement, default_format: "CSV" })
-        response.body
-                .group_by { |row| row[0] }
-                .transform_values { |columns| columns.map { |c| { name: c[1], data_type: c[2] } } }
-                .map { |table, columns| { schema: "public", table: table, columns: columns } }
+        rows = driver.execute(statement, "CSV")
+        rows.group_by { |row| row[0] }
+            .transform_values { |columns| columns.map { |c| { name: c[1], data_type: c[2] } } }
+            .map { |table, columns| { schema: "public", table: table, columns: columns } }
       end
 
       def preview_statement
         "SELECT * FROM {table} LIMIT 10"
       end
 
       def explain(statement)
-        connection.explain(statement)
+        driver.execute("EXPLAIN #{statement.gsub(/\A(\s*EXPLAIN)/io, '')}", "TSV")
       end
 
       protected
 
-      def connection
-        @connection ||= ClickHouse::Connection.new(config)
+      def driver
+        @driver ||= begin
+          driver = SUPPORTED_DRIVERS_MAPPING.keys.find { |driver| installed?(driver) }
+          raise Blazer::Error, "ClickHouse driver not installed!" unless driver
+
+          SUPPORTED_DRIVERS_MAPPING[driver].new(config)
+        end
       end
 
       def config
         @config ||= begin
           uri = URI.parse(settings["url"])
-          options = {
+          {
             scheme: uri.scheme,
             host: uri.host,
             port: uri.port,
             username: uri.user,
             password: uri.password,
             database: uri.path.split("/").last
           }.compact
-
-          ClickHouse::Config.new(**options)
         end
       end
+
+      def installed?(driver_name)
+        Gem::Specification.find_by_name(driver_name)
+        true
+      rescue Gem::LoadError
+        false
+      end
     end
   end
 end