commands: Support outputting <-chan interface{}

commands/command.go

@@ -125,6 +125,15 @@ func (c *Command) Call(req Request) Response {
 		isChan = actualType.Kind() == reflect.Chan
 	}
 
+	if isChan {
+		if ch, ok := output.(<-chan interface{}); ok {
+			output = ch
+
+		} else if ch, ok := output.(chan interface{}); ok {
+			output = (<-chan interface{})(ch)
+		}
+	}
+
 	// If the command specified an output type, ensure the actual value returned is of that type
 	if cmd.Type != nil && !isChan {
 		expectedType := reflect.TypeOf(cmd.Type)

commands/http/client.go

@@ -167,7 +167,7 @@ func getResponse(httpRes *http.Response, req cmds.Request) (cmds.Response, error
 			}
 		}()
 
-		res.SetOutput(outChan)
+		res.SetOutput((<-chan interface{})(outChan))
 		return res, nil
 	}
 

commands/http/handler.go

@@ -112,6 +112,10 @@ func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// if output is a channel and user requested streaming channels,
 	// use chunk copier for the output
 	_, isChan := res.Output().(chan interface{})
+	if !isChan {
+		_, isChan = res.Output().(<-chan interface{})
+	}
+
 	streamChans, _, _ := req.Option("stream-channels").Bool()
 	if isChan && streamChans {
 		// w.WriteString(transferEncodingHeader + ": chunked\r\n")

commands/response.go

@@ -50,7 +50,8 @@ func marshalJson(value interface{}) (io.Reader, error) {
 
 var marshallers = map[EncodingType]Marshaler{
 	JSON: func(res Response) (io.Reader, error) {
-		if ch, ok := res.Output().(chan interface{}); ok {
+		ch, ok := res.Output().(<-chan interface{})
+		if ok {
 			return &ChannelMarshaler{
 				Channel:   ch,
 				Marshaler: marshalJson,

core/commands/add.go

@@ -72,7 +72,7 @@ remains to be implemented.
 	},
 	Marshalers: cmds.MarshalerMap{
 		cmds.Text: func(res cmds.Response) (io.Reader, error) {
-			outChan, ok := res.Output().(chan interface{})
+			outChan, ok := res.Output().(<-chan interface{})
 			if !ok {
 				return nil, u.ErrCast()
 			}

core/commands/ping.go

@@ -44,7 +44,7 @@ trip latency information.
 	},
 	Marshalers: cmds.MarshalerMap{
 		cmds.Text: func(res cmds.Response) (io.Reader, error) {
-			outChan, ok := res.Output().(chan interface{})
+			outChan, ok := res.Output().(<-chan interface{})
 			if !ok {
 				return nil, u.ErrCast()
 			}