[Redis 6.2] Add HRANDFIELD command

lib/redis.rb

@@ -1907,7 +1907,7 @@ def zmscore(key, *members)
   # @example Get multiple random members
   #   redis.zrandmember("zset", 2)
   #     # => ["a", "b"]
-  # @example Gem multiple random members with scores
+  # @example Get multiple random members with scores
   #   redis.zrandmember("zset", 2, with_scores: true)
   #     # => [["a", 2.0], ["b", 3.0]]
   #
@@ -2457,6 +2457,48 @@ def mapped_hmget(key, *fields)
     end
   end
 
+  # Get one or more random fields from a hash.
+  #
+  # @example Get one random field
+  #   redis.hrandfield("hash")
+  #     # => "f1"
+  # @example Get multiple random fields
+  #   redis.hrandfield("hash", 2)
+  #     # => ["f1, "f2"]
+  # @example Get multiple random fields with values
+  #   redis.hrandfield("hash", 2, with_values: true)
+  #     # => [["f1", "s1"], ["f2", "s2"]]
+  #
+  # @param [String] key
+  # @param [Integer] count
+  # @param [Hash] options
+  #   - `:with_values => true`: include values in output
+  #
+  # @return [nil, String, Array<String>, Array<[String, Float]>]
+  #   - when `key` does not exist, `nil`
+  #   - when `count` is not specified, a field name
+  #   - when `count` is specified and `:with_values` is not specified, an array of field names
+  #   - when `:with_values` is specified, an array with `[field, value]` pairs
+  def hrandfield(key, count = nil, withvalues: false, with_values: withvalues)
+    if with_values && count.nil?
+      raise ArgumentError, "count argument must be specified"
+    end
+
+    args = [:hrandfield, key]
+    args << count if count
+    args << "WITHVALUES" if with_values
+
+    synchronize do |client|
+      client.call(args) do |reply|
+        if with_values
+          Pairify.call(reply)
+        else
+          reply
+        end
+      end
+    end
+  end
+
   # Delete one or more hash fields.
   #
   # @param [String] key
@@ -3652,6 +3694,14 @@ def method_missing(command, *args) # rubocop:disable Style/MissingRespondToMissi
     end
   }
 
+  Pairify = lambda { |value|
+    if value.respond_to?(:each_slice)
+      value.each_slice(2).to_a
+    else
+      value
+    end
+  }
+
   Floatify = lambda { |value|
     case value
     when "inf"

lib/redis/distributed.rb

@@ -774,6 +774,10 @@ def mapped_hmget(key, *fields)
       Hash[*fields.zip(hmget(key, *fields)).flatten]
     end
 
+    def hrandfield(key, count = nil, **options)
+      node_for(key).hrandfield(key, count, **options)
+    end
+
     # Delete one or more hash fields.
     def hdel(key, *fields)
       node_for(key).hdel(key, *fields)

test/lint/hashes.rb

@@ -103,6 +103,30 @@ def test_hkeys
       assert_equal ["f1", "f2"], r.hkeys("foo")
     end
 
+    def test_hrandfield
+      target_version("6.2") do
+        assert_nil r.hrandfield("foo")
+        assert_equal [], r.hrandfield("foo", 1)
+
+        error = assert_raises(ArgumentError) do
+          r.hrandfield("foo", with_values: true)
+        end
+        assert_equal "count argument must be specified", error.message
+
+        r.hset("foo", "f1", "s1")
+        r.hset("foo", "f2", "s2")
+
+        assert ["f1", "f2"].include?(r.hrandfield("foo"))
+        assert_equal ["f1", "f2"], r.hrandfield("foo", 2).sort
+        assert_equal 4, r.hrandfield("foo", -4).size
+
+        r.hrandfield("foo", 2, with_values: true) do |(field, value)|
+          assert ["f1", "f2"].include?(field)
+          assert ["s1", "s2"].include?(value)
+        end
+      end
+    end
+
     def test_hvals
       assert_equal [], r.hvals("foo")