cmd/rc: add --json flag for structured JSON input

cmd/rc/rc.go

@@ -21,12 +21,14 @@ import (
 var (
 	noOutput  = false
 	url       = "http://localhost:5572/"
+	jsonInput = ""
 )
 
 func init() {
 	cmd.Root.AddCommand(commandDefintion)
 	commandDefintion.Flags().BoolVarP(&noOutput, "no-output", "", noOutput, "If set don't output the JSON result.")
 	commandDefintion.Flags().StringVarP(&url, "url", "", url, "URL to connect to rclone remote control.")
+	commandDefintion.Flags().StringVarP(&jsonInput, "json", "", jsonInput, "Input JSON - use instead of key=value args.")
 }
 
 var commandDefintion = &cobra.Command{
@@ -40,6 +42,10 @@ Arguments should be passed in as parameter=value.
 
 The result will be returned as a JSON object by default.
 
+The --json parameter can be used to pass in a JSON blob as an input
+instead of key=value arguments.  This is the only way of passing in
+more complicated values.
+
 Use "rclone rc" to see a list of all possible commands.`,
 	Run: func(command *cobra.Command, args []string) {
 		cmd.CheckArgs(0, 1E9, command, args)
@@ -115,14 +121,25 @@ func run(args []string) (err error) {
 
 	// parse input
 	in := make(rc.Params)
-	for _, param := range args[1:] {
+	params := args[1:]
+	if jsonInput == "" {
+		for _, param := range params {
 			equals := strings.IndexRune(param, '=')
 			if equals < 0 {
-			return errors.Errorf("No '=' found in parameter %q", param)
+				return errors.Errorf("no '=' found in parameter %q", param)
 			}
 			key, value := param[:equals], param[equals+1:]
 			in[key] = value
 		}
+	} else {
+		if len(params) > 0 {
+			return errors.New("can't use --json and parameters together")
+		}
+		err = json.Unmarshal([]byte(jsonInput), &in)
+		if err != nil {
+			return errors.Wrap(err, "bad --json input")
+		}
+	}
 
 	// Do the call
 	out, callErr := doCall(path, in)

docs/content/rc.md

@@ -67,6 +67,25 @@ $ rclone rc rc/noop param1=one param2=two
 Run `rclone rc` on its own to see the help for the installed remote
 control commands.
 
+`rclone rc` also supports a `--json` flag which can be used to send
+more complicated input parameters.
+
+```
+$ rclone rc --json '{ "p1": [1,"2",null,4], "p2": { "a":1, "b":2 } }' rc/noop
+{
+	"p1": [
+		1,
+		"2",
+		null,
+		4
+	],
+	"p2": {
+		"a": 1,
+		"b": 2
+	}
+}
+```
+
 ## Supported commands
 <!--- autogenerated start - run make rcdocs - don't edit here -->
 ### cache/expire: Purge a remote from cache