Initial commit

lib/carto/db/sql_interface.rb

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+module Carto
+  module Db
+    # Simple database interface that can be used through Sequel or ActiveRecord connections
+    # (e.g. as returned by User#in_database and Carto::User#in_database respectively)
+    # It provides two operations:
+    # * run to execute an SQL statement disregarding any results
+    # * fetch to obtain the resulting rows of a SQL SELECT
+    #   the result is an array of hashes using symbol keys (with the name of the columns).
+    #   The types of tuple values may vary between Sequel and ActiveRecord (ActiveRecord keeps them as text)
+    #   If a block is passed to this method it receives each of the rows
+    class SqlInterface
+      class Error < RuntimeError; end
+
+      module SequelConnection
+        def run(sql)
+          @db_connection.run(sql)
+          nil
+        rescue Sequel::DatabaseError => e
+          raise Error.new(e.message)
+        end
+
+        def fetch(sql, &block)
+          if block
+            @db_connection.fetch(sql, &block)
+            nil
+          else
+            @db_connection.fetch(sql, &block).all
+          end
+        rescue Sequel::DatabaseError => e
+          raise Error.new(e.message)
+        end
+      end
+
+      module ActiveRecordConnection
+        def run(sql)
+          @db_connection.execute(sql)
+          nil
+        rescue ActiveRecord::StatementInvalid => e
+          raise Error.new(e.message)
+        end
+
+        def fetch(sql, &block)
+          rows = @db_connection.select_all(sql).map(&:symbolize_keys)
+          if block
+            rows.each &block
+            nil
+          else
+            rows
+          end
+        rescue ActiveRecord::StatementInvalid => e
+          raise Error.new(e.message)
+        end
+      end
+
+      def initialize(db_connection)
+        @db_connection = db_connection
+        case db_connection
+        when Sequel::Postgres::Database
+          extend SequelConnection
+        when ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
+          extend ActiveRecordConnection
+        else
+          raise "Invalid database connection"
+        end
+      end
+    end
+  end
+end