Deprecate inferred JOINs with includes + SQL snippets.

See the CHANGELOG for details.

Fixes #950.

4 files changed, 29 insertions, 7 deletions

diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index 3759af26d6..0209ce36df 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -20,7 +20,7 @@ module ActiveRecord
         # It's okay to just apply all these like this. The options will only be present if the
         # association supports that option; this is enforced by the association builder.
         scope = scope.apply_finder_options(options.slice(
-          :readonly, :include, :order, :limit, :joins, :group, :having, :offset, :select))
+          :readonly, :include, :references, :order, :limit, :joins, :group, :having, :offset, :select))
 
         if options[:through] && !options[:include]
           scope = scope.includes(source_options[:include])
diff --git a/activerecord/lib/active_record/associations/builder/association.rb b/activerecord/lib/active_record/associations/builder/association.rb
index d4f59100e8..6e2e5f9de0 100644
--- a/activerecord/lib/active_record/associations/builder/association.rb
+++ b/activerecord/lib/active_record/associations/builder/association.rb
@@ -1,7 +1,7 @@
 module ActiveRecord::Associations::Builder
   class Association #:nodoc:
     class_attribute :valid_options
-    self.valid_options = [:class_name, :foreign_key, :select, :conditions, :include, :extend, :readonly, :validate]
+    self.valid_options = [:class_name, :foreign_key, :select, :conditions, :include, :extend, :readonly, :validate, :references]
 
     # Set by subclasses
     class_attribute :macro
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 7838271e5c..01019db2cc 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 require 'active_support/core_ext/object/blank'
+require 'active_support/deprecation'
 
 module ActiveRecord
   # = Active Record Relation
@@ -520,9 +521,30 @@ module ActiveRecord
 
       # always convert table names to downcase as in Oracle quoted table names are in uppercase
       joined_tables = joined_tables.flatten.compact.map { |t| t.downcase }.uniq
-
-      (tables_in_string(to_sql) - joined_tables).any? ||
-      (references_values - joined_tables).any?
+      string_tables = tables_in_string(to_sql)
+
+      if (references_values - joined_tables).any?
+        true
+      elsif (string_tables - joined_tables).any?
+        ActiveSupport::Deprecation.warn(
+          "It looks like you are eager loading table(s) (one of: #{string_tables.join(', ')}) " \
+          "that are referenced in a string SQL snippet. For example: \n" \
+          "\n" \
+          "    Post.includes(:comments).where(\"comments.title = 'foo'\")\n" \
+          "\n" \
+          "Currently, Active Record recognises the table in the string, and knows to JOIN the " \
+          "comments table to the query, rather than loading comments in a separate query. " \
+          "However, doing this without writing a full-blown SQL parser is inherently flawed. " \
+          "Since we don't want to write an SQL parser, we are removing this functionality. " \
+          "From now on, you must explicitly tell Active Record when you are referencing a table " \
+          "from a string:\n" \
+          "\n" \
+          "    Post.includes(:comments).where(\"comments.title = 'foo'\").references(:comments)\n\n"
+        )
+        true
+      else
+        false
+      end
     end
 
     def tables_in_string(string)
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index c25570d758..7131aa29b6 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -122,7 +122,7 @@ module ActiveRecord
       result
     end
 
-    VALID_FIND_OPTIONS = [ :conditions, :include, :joins, :limit, :offset, :extend,
+    VALID_FIND_OPTIONS = [ :conditions, :include, :joins, :limit, :offset, :extend, :references,
                            :order, :select, :readonly, :group, :having, :from, :lock ]
 
     def apply_finder_options(options)
@@ -133,7 +133,7 @@ module ActiveRecord
       finders = options.dup
       finders.delete_if { |key, value| value.nil? && key != :limit }
 
-      ([:joins, :select, :group, :order, :having, :limit, :offset, :from, :lock, :readonly] & finders.keys).each do |finder|
+      ((VALID_FIND_OPTIONS - [:conditions, :include, :extend]) & finders.keys).each do |finder|
         relation = relation.send(finder, finders[finder])
       end