Flip the values for serializable_hash_with_legacy_only

Author: bpardee

lib/mongoid/config.rb

@@ -259,15 +259,15 @@ def validate_isolation_level!(level)
     # consequences of duplicate index checking.
     option :allow_duplicate_index_declarations, default: false
 
-    # When this flag is false, performing a serializable_hash(only: []) will
+    # When this flag is true, performing a serializable_hash(only: []) will
     # result in all fields being included. This is the traditional (and default)
     # behavior in Mongoid 9 and earlier.
     #
-    # Setting this flag to true will change the behavior to suppress all fields
+    # Setting this flag to false will change the behavior to suppress all fields
     # in the serialized hash. This will be the default in Mongoid 10.
     #
     # See https://jira.mongodb.org/browse/MONGOID-5892 for more details.
-    option :serializable_hash_with_legacy_only, default: false
+    option :serializable_hash_with_legacy_only, default: true
 
     # Returns the Config singleton, for use in the configure DSL.
     #

lib/mongoid/serializable.rb

@@ -79,11 +79,11 @@ def serializable_hash(options = nil)
     def field_names(options)
       names = (as_attributes.keys + attribute_names).uniq.sort
 
+      only = Array.wrap(options[:only]).map(&:to_s)
       except = Array.wrap(options[:except]).map(&:to_s)
       except |= [self.class.discriminator_key] unless Mongoid.include_type_for_serialization
 
-      only = Array.wrap(options[:only]).map(&:to_s)
-      if !options[:only].nil? && (!Mongoid.serializable_hash_with_legacy_only || !only.empty?)
+      if !options[:only].nil? && (Mongoid.serializable_hash_with_legacy_only || !only.empty?)
         names &= only
       elsif !except.empty?
         names -= except

spec/mongoid/serializable_spec.rb

@@ -302,16 +302,16 @@
           )
         end
 
-        context "when serializable_hash_with_legacy_only == false" do # default for <= 9
-          config_override :serializable_hash_with_legacy_only, false
+        context "when serializable_hash_with_legacy_only == true" do # default for <= 9
+          config_override :serializable_hash_with_legacy_only, true
 
           it "includes all fields when passed an empty array" do
             expect(person.serializable_hash(only: [])).to include attributes
           end
         end
 
-        context "when serializable_hash_with_legacy_only == true" do # default for >= 10
-          config_override :serializable_hash_with_legacy_only, true
+        context "when serializable_hash_with_legacy_only == false" do # default for >= 10
+          config_override :serializable_hash_with_legacy_only, false
 
           it "doesn't include any fields when passed an empty array" do
             expect(person.serializable_hash(only: [])).to be_empty