Add expire_after_seconds to index options.

[ close #2443 ]

CHANGELOG.md

@@ -7,6 +7,14 @@ For instructions on upgrading to newer versions, visit
 
 ### New Features
 
+* \#2443 `expire_after_seconds` is now a valid index option.
+
+        class Event
+          include Mongoid::Document
+          field :status, type: Integer
+          index({ status: 1 }, { expire_after_seconds: 3600 })
+        end
+
 * Added `Document.first_or_create!` and `Criteria#first_or_create!`. This
   raises a validations error if creation fails validation.
 

lib/mongoid/indexes.rb

@@ -99,6 +99,9 @@ def normalize_index_options(options)
         opts = options || {}
         opts[:dropDups] = opts.delete(:drop_dups) if opts.has_key?(:drop_dups)
         opts[:bucketSize] = opts.delete(:bucket_size) if opts.has_key?(:bucket_size)
+        if opts.has_key?(:expire_after_seconds)
+          opts[:expireAfterSeconds] = opts.delete(:expire_after_seconds)
+        end
         opts
       end
 

lib/mongoid/indexes/validators/options.rb

@@ -7,7 +7,19 @@ module Validators
       module Options
         extend self
 
-        VALID_OPTIONS = [ :background, :drop_dups, :name, :sparse, :unique, :max, :min, :bits, :bucket_size ]
+        VALID_OPTIONS = [
+          :background,
+          :drop_dups,
+          :name,
+          :sparse,
+          :unique,
+          :max,
+          :min,
+          :bits,
+          :bucket_size,
+          :expire_after_seconds
+        ]
+
         VALID_TYPES = [ 1, -1, "2d", "geoHaystack" ]
 
         # Validate the index specification.

spec/mongoid/indexes_spec.rb

@@ -227,6 +227,21 @@ def self.hereditary?
       end
     end
 
+    context "when providing an expire_after_seconds option" do
+
+      before do
+        klass.index({ name: 1 }, { expire_after_seconds: 3600 })
+      end
+
+      let(:options) do
+        klass.index_options[name: 1]
+      end
+
+      it "sets the index with sparse options" do
+        options.should eq(expireAfterSeconds: 3600)
+      end
+    end
+
     context "when providing an invalid option" do
 
       it "raises an error" do