Determine if flags were actually passed in (sub)command invocation in golang's cobra/viper

Question

I have a cobra command

var mycommandCmd = &cobra.Command{
    Use:   "mycommand",
    PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
        viper.BindPFlags(cmd.Flags())

and a subcommand

var mysubcommandCmd = &cobra.Command{
    Use:   "mysubcommand",
    Args:  cobra.ExactArgs(1),
    RunE: func(cmd *cobra.Command, args []string) error {
        viper.BindPFlags(cmd.Flags())

which I of course bind together

mycommandCmd.AddCommand(mysubcommandCmd)

I also have some flags for both of them

mycommandCmd.PersistentFlags().BoolP("foo", "", true, "Whether to foo")
mysubcommandCmd.Flags().BoolP("foobar", "", true,  "Whether to foobar")

My question is the following:

Assuming the end go binary is named prog, is there a (cobra / viper) built in way of checking of whether any flags were actually passed during subcommand invocation?

i.e. how can I programmatically distinguish between this

prog mycommand mysubcommand --foobar

and this

prog mycommand mysubcommand

Checking against the default flag values will not work of course (and does not scale against the flag number)

score 2 · Accepted Answer · answered Nov 16 '21 at 17:41

2

You can do:

isSet:=cmd.Flags().Lookup("foobar").Changed

That should return if the flag was set, or if the default value was used.

answered Nov 16 '21 at 17:41

Burak Serdar

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so in order for me to check say if NONE of them was actually set, this has to be done for all flags, one by one, right? – pkaramol Nov 16 '21 at 17:55
For bools, yes. For strings, you can give an empty default and check if it is empty. – Burak Serdar Nov 16 '21 at 17:58

Determine if flags were actually passed in (sub)command invocation in golang's cobra/viper

1 Answers1