Add go template shell completion for --format

The --format flags accepts go template strings. I use this often but I
consistently forget the field names. This commit adds a way to provide
shell completion for the --format flag. It works by automatically
receiving the field names with the reflect package from the given
struct. This requires almost no maintenance since this ensures that we
always use the correct field names. This also works for nested structs.

```
$ podman ps --format "{{.P"
{{.Pid}}      {{.PIDNS}}    {{.Pod}}      {{.PodName}}  {{.Ports}}
```

NOTE: This only works when you use quotes otherwise the shell does not
provide completions. Also this does not work for fish at the moment.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

2 files changed, 2 insertions, 2 deletions

diff --git a/cmd/podman/networks/inspect.go b/cmd/podman/networks/inspect.go
index 953f5e6e8..a05b9026d 100644
--- a/cmd/podman/networks/inspect.go
+++ b/cmd/podman/networks/inspect.go
@@ -33,7 +33,7 @@ func init() {
 
 	formatFlagName := "format"
 	flags.StringVarP(&inspectOpts.Format, formatFlagName, "f", "", "Pretty-print network to JSON or using a Go template")
-	_ = networkinspectCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+	_ = networkinspectCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(nil))
 }
 
 func networkInspect(_ *cobra.Command, args []string) error {
diff --git a/cmd/podman/networks/list.go b/cmd/podman/networks/list.go
index bc100da8c..e1b182cbf 100644
--- a/cmd/podman/networks/list.go
+++ b/cmd/podman/networks/list.go
@@ -41,7 +41,7 @@ var (
 func networkListFlags(flags *pflag.FlagSet) {
 	formatFlagName := "format"
 	flags.StringVar(&networkListOptions.Format, formatFlagName, "", "Pretty-print networks to JSON or using a Go template")
-	_ = networklistCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+	_ = networklistCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(ListPrintReports{}))
 
 	flags.BoolVarP(&networkListOptions.Quiet, "quiet", "q", false, "display only names")
 	flags.BoolVar(&noTrunc, "no-trunc", false, "Do not truncate the network ID")