feat(printer): add a json function in the template printer (#4667)

Author: Gnoale

cmd/scw/testdata/test-all-usage-help-output-usage.golden

@@ -76,6 +76,10 @@ Visit https://golang.org/pkg/text/template/ to learn more about Go template form
 	foo||11111111-1111-1111-1111-111111111111
 	bar||22222222-2222-2222-2222-222222222222
 
+In case the command returns data that is not correctly converted, for instance a []byte, you can use the json function to marshal the data as json and print it as is.
+
+       scw instance server list -o template="{{ json . }}"
+
 USAGE:
   scw help output
 

core/printer.go

@@ -106,6 +106,17 @@ func setupJSONPrinter(printer *Printer, opts string) error {
 }
 
 func setupTemplatePrinter(printer *Printer, opts string) error {
+	funcMap := template.FuncMap{
+		"json": func(v interface{}) string {
+			b, err := json.Marshal(v)
+			if err != nil {
+				return fmt.Sprintf("Error: %s", err)
+			}
+
+			return string(b)
+		},
+	}
+
 	printer.printerType = PrinterTypeTemplate
 	if opts == "" {
 		return &CliError{
@@ -115,7 +126,7 @@ func setupTemplatePrinter(printer *Printer, opts string) error {
 		}
 	}
 
-	t, err := template.New("OutputFormat").Parse(opts)
+	t, err := template.New("OutputFormat").Funcs(funcMap).Parse(opts)
 	if err != nil {
 		return err
 	}

docs/commands/help.md

@@ -160,6 +160,10 @@ Visit https://golang.org/pkg/text/template/ to learn more about Go template form
 	foo||11111111-1111-1111-1111-111111111111
 	bar||22222222-2222-2222-2222-222222222222
 
+In case the command returns data that is not correctly converted, for instance a []byte, you can use the json function to marshal the data as json and print it as is.
+
+       scw instance server list -o template="{{ json . }}"
+
 
 Output formatting in the CLI
 
@@ -237,6 +241,10 @@ Visit https://golang.org/pkg/text/template/ to learn more about Go template form
 	foo||11111111-1111-1111-1111-111111111111
 	bar||22222222-2222-2222-2222-222222222222
 
+In case the command returns data that is not correctly converted, for instance a []byte, you can use the json function to marshal the data as json and print it as is.
+
+       scw instance server list -o template="{{ json . }}"
+
 
 **Usage:**
 

internal/namespaces/help/output.go

@@ -77,5 +77,9 @@ Visit https://golang.org/pkg/text/template/ to learn more about Go template form
 
 	foo||11111111-1111-1111-1111-111111111111
 	bar||22222222-2222-2222-2222-222222222222
+
+In case the command returns data that is not correctly converted, for instance a []byte, you can use the json function to marshal the data as json and print it as is.
+
+       scw instance server list -o template="{{ json . }}"
 `
 )