Support for sorting.

README

@@ -57,8 +57,6 @@ type
 
 * Capped collection support.
 
-* Implement order_by (right now, sort order is ignored)
-
 * More code comments. More text in this file.
 
 * Support more types: REF, SYMBOL, CODE_W_SCOPE, etc.

lib/mongo/message/query_message.rb

@@ -1,5 +1,6 @@
 require 'mongo/message/message'
 require 'mongo/message/opcodes'
+require 'mongo/util/ordered_hash'
 
 module XGen
   module Mongo
@@ -13,7 +14,30 @@ module XGen
           write_string("#{db_name}.#{collection_name}")
           write_int(query.number_to_skip)
           write_int(query.number_to_return)
-          write_doc(query.selector)
+          sel = query.selector
+          if query.order_by
+            sel = OrderedHash.new
+            sel['query'] = query.selector
+            sel['orderby'] = case query.order_by
+                             when Array
+                               if query.order_by.empty? # Empty array of order_by values 
+                                []
+                               else
+                                 case query.order_by[0]
+                                 when Hash # Array of hashes
+                                   query.order_by
+                                 else      # ['a', 'b']
+                                   query.order_by.collect { |v| {v => 1} } # Assume ascending order for all values
+                                 end
+                               end
+                             when Hash # Should be an ordered hash, but this message doesn't care
+                               a = []
+                               query.order_by.each { |k,v| a << {k => v }}
+                               a
+                             end
+                               
+          end
+          write_doc(sel)
           write_doc(query.fields) if query.fields
         end
 

tests/test_db_api.rb

@@ -107,16 +107,30 @@ class DBAPITest < Test::Unit::TestCase
     @coll.insert('b' => 3)
 
     # Sorting (ascending)
-    order_by = OrderedHash.new
-    order_by['a'] = 1
-    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => order_by).map
+    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => [{'a' => 1}]).map
     assert_equal 2, docs.size
     assert_equal 1, docs.first['a']
 
     # Sorting (descending)
-    order_by = OrderedHash.new
-    order_by['a'] = -1
-    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => order_by).map
+    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => [{'a' => -1}]).map
+    assert_equal 2, docs.size
+    assert_equal 2, docs.first['a']
+
+    # Sorting using array of names; assumes ascending order
+    # NOTE: Mongo itself does not yet properly sort by multiple names
+    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => ['a']).map
+    assert_equal 2, docs.size
+    assert_equal 1, docs.first['a']
+
+    # Sorting using empty array; no order guarantee but should not blow up.
+    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => [{'a' => -1}]).map
+    assert_equal 2, docs.size
+
+    # Sorting using ordered hash. You can use an unordered one, but then the
+    # order of the keys won't be guaranteed thus your sort won't make sense.
+    oh = OrderedHash.new
+    oh['a'] = -1
+    docs = @coll.find({'a' => { '$lt' => 10 }}, :sort => oh).map
     assert_equal 2, docs.size
     assert_equal 2, docs.first['a']
   end