Add ability to override the session globally via Mongoid.override_ses…

…sion.

CHANGELOG.md

@@ -7,10 +7,12 @@ For instructions on upgrading to newer versions, visit
 
 ### New Features
 
-* \#2080/\#2087 The database that Mongoid persists to can now be overridden
-  on a global level for cases where `Model#with` is not a viable option.
+* \#2080/\#2087 The database or session that Mongoid persists to can now be
+  overridden on a global level for cases where `Model#with` is not a viable
+  option.
 
         Mongoid.override_database(:secondary)
+        Mongoid.override_session(:secondary)
 
         Band.create(name: "Placebo") #=> Persists to secondary.
         band.albums.create #=> Persists to secondary.
@@ -20,6 +22,7 @@ For instructions on upgrading to newer versions, visit
     to nil if you no longer want the override to happen.
 
         Mongoid.override_database(nil)
+        Mongoid.override_session(nil)
 
 * \#1989 Criteria `count`, `size` and `length` now behave as Active Record
   with regards to database access.

lib/mongoid/config.rb

@@ -85,6 +85,20 @@ def override_database(name)
       Threaded.database_override = name
     end
 
+    # Override the session to use globally.
+    #
+    # @example Override the session globally.
+    #   config.override_session(:optional)
+    #
+    # @param [ String, Symbol ] name The name of the session.
+    #
+    # @return [ String, Symbol ] The global override.
+    #
+    # @since 3.0.0
+    def override_session(name)
+      Threaded.session_override = name ? name.to_s : nil
+    end
+
     # Purge all data in all collections, including indexes.
     #
     # @example Purge all data.

lib/mongoid/sessions.rb

@@ -227,6 +227,20 @@ def persistence_options
         Threaded.persistence_options(self)
       end
 
+      # Get the overridden session name. This either can be overridden by
+      # using +Model.with+ or by overriding at the global level via
+      # +Mongoid.override_session(:name)+.
+      #
+      # @example Get the overridden session name.
+      #   Model.session_override
+      #
+      # @return [ String, Symbol ] The overridden session name.
+      #
+      # @since 3.0.0
+      def session_override
+        persistence_options.try { |opts| opts[:session] } || Threaded.session_override
+      end
+
       # Give this model specific custom default storage options.
       #
       # @example Store this model by default in "artists"
@@ -356,7 +370,7 @@ def __session_name__
       #
       # @since 3.0.0
       def __session__
-        if persistence_options && name = persistence_options[:session]
+        if name = session_override
           Sessions.with_name(name)
         elsif storage_options && name = storage_options[:session]
           Sessions.with_name(name)

lib/mongoid/threaded.rb

@@ -322,6 +322,32 @@ def selection=(value)
       Thread.current["[mongoid]:selection"] = value
     end
 
+    # Get the global session override.
+    #
+    # @example Get the global session override.
+    #   Threaded.session_override
+    #
+    # @return [ String, Symbol ] The override.
+    #
+    # @since 3.0.0
+    def session_override
+      Thread.current["[mongoid]:session-override"]
+    end
+
+    # Set the global session override.
+    #
+    # @example Set the global session override.
+    #   Threaded.session_override = :testing
+    #
+    # @param [ String, Symbol ] The global override name.
+    #
+    # @return [ String, Symbol ] The override.
+    #
+    # @since 3.0.0
+    def session_override=(name)
+      Thread.current["[mongoid]:session-override"] = name
+    end
+
     # Get the mongoid scope stack for chained criteria.
     #
     # @example Get the scope stack.

spec/mongoid/sessions_spec.rb

@@ -753,4 +753,31 @@
       end
     end
   end
+
+  context "when overriding the default session", config: :mongohq do
+
+    context "when the override is global" do
+
+      before do
+        Mongoid.override_session(:mongohq_single)
+      end
+
+      after do
+        Band.with(database: "mongoid").delete_all
+        Mongoid.override_session(nil)
+      end
+
+      let!(:band) do
+        Band.with(database: "mongoid").create(name: "Tool")
+      end
+
+      let(:persisted) do
+        Band.with(session: :mongohq_single, database: "mongoid").where(name: "Tool").first
+      end
+
+      it "persists to the overridden session" do
+        persisted.should eq(band)
+      end
+    end
+  end
 end