Apply monkey patches for SQL Server connections only (#933) (#1054)

Author: djezzzl

CHANGELOG.md

@@ -1,3 +1,9 @@
+## Unreleased
+
+#### Fixed
+
+[#1054](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1054) Conditionally apply SQL Server monkey patches to ActiveRecord so that it is safe to use this gem alongside other database adapters (e.g. PostgreSQL) in a multi-database Rails app
+
 ## v6.0.2
 
 #### Fixed

lib/active_record/connection_adapters/sqlserver/core_ext/attribute_methods.rb

@@ -10,6 +10,8 @@ module AttributeMethods
           private
 
           def attributes_for_update(attribute_names)
+            return super unless self.class.connection.adapter_name == "SQLServer"
+
             super.reject do |name|
               column = self.class.columns_hash[name]
               column && column.respond_to?(:is_identity?) && column.is_identity?

lib/active_record/connection_adapters/sqlserver/core_ext/calculations.rb

@@ -10,6 +10,8 @@ module CoreExt
         module Calculations
           # Same as original except we don't perform PostgreSQL hack that removes ordering.
           def calculate(operation, column_name)
+            return super unless klass.connection.adapter_name == "SQLServer"
+
             if has_include?(column_name)
               relation = apply_join_dependency
 
@@ -29,6 +31,8 @@ def calculate(operation, column_name)
           private
 
           def build_count_subquery(relation, column_name, distinct)
+            return super unless klass.connection.adapter_name == "SQLServer"
+
             super(relation.unscope(:order), column_name, distinct)
           end
 

lib/active_record/connection_adapters/sqlserver/core_ext/explain.rb

@@ -9,6 +9,8 @@ module Explain
           SQLSERVER_STATEMENT_REGEXP = /N'(.+)', N'(.+)', (.+)/
 
           def exec_explain(queries)
+            return super unless connection.adapter_name == "SQLServer"
+
             unprepared_queries = queries.map do |(sql, binds)|
               [unprepare_sqlserver_statement(sql, binds), binds]
             end

lib/active_record/connection_adapters/sqlserver/core_ext/finder_methods.rb

@@ -12,6 +12,8 @@ module FinderMethods
 
           # Same as original except we order by values in distinct select if present.
           def construct_relation_for_exists(conditions)
+            return super unless klass.connection.adapter_name == "SQLServer"
+
             conditions = sanitize_forbidden_attributes(conditions)
 
             if distinct_value && offset_value

lib/active_record/connection_adapters/sqlserver/core_ext/preloader.rb

@@ -10,6 +10,8 @@ module Preloader
           private
 
           def records_for(ids)
+            return super unless klass.connection.adapter_name == "SQLServer"
+
             ids.each_slice(in_clause_length).flat_map do |slice|
               scope.where(association_key_name => slice).load do |record|
                 # Processing only the first owner