// printField prints the field of the config struct for the flag.Usage
func (e *EnvironmentLoader) printField(prefix string, field *structs.Field) {
fieldName := e.generateFieldName(prefix, field)
if field.IsExported() {
switch {
case field.Kind() == reflect.Struct && !implementsTextUnmarshaler(field):
for _, f := range field.Fields() {
e.printField(fieldName, f)
}
default:
fmt.Println(" ", fieldName)
}
}
}
// processField generates a flag based on the given field and fieldName. If a
// nested struct is detected, a flag for each field of that nested struct is
// generated too.
func (f *FlagLoader) processField(fieldName string, field *structs.Field) error {
if f.CamelCase {
fieldName = strings.Join(camelcase.Split(fieldName), "-")
}
switch field.Kind() {
case reflect.Struct:
for _, ff := range field.Fields() {
flagName := field.Name() + "-" + ff.Name()
if f.Flatten {
// first check if it's set or not, because if we have duplicate
// we don't want to break the flag. Panic by giving a readable
// output
f.flagSet.VisitAll(func(fl *flag.Flag) {
if strings.ToLower(ff.Name()) == fl.Name {
// already defined
panic(fmt.Sprintf("flag '%s' is already defined in outer struct", fl.Name))
}
})
flagName = ff.Name()
}
if err := f.processField(flagName, ff); err != nil {
return err
}
}
default:
// Add custom prefix to the flag if it's set
if f.Prefix != "" {
fieldName = f.Prefix + "-" + fieldName
}
// we only can get the value from expored fields, unexported fields panics
if field.IsExported() {
// use built-in or custom flag usage message
flagUsageFunc := flagUsageDefault
if f.FlagUsageFunc != nil {
flagUsageFunc = f.FlagUsageFunc
}
f.flagSet.Var(newFieldValue(field), flagName(fieldName), flagUsageFunc(fieldName))
}
}
return nil
}
// processField generates a flag based on the given field and fieldName. If a
// nested struct is detected, a flag for each field of that nested struct is
// generated too.
func (f *FlagLoader) processField(flagSet *flag.FlagSet, fieldName string, field *structs.Field) error {
if !field.IsExported() {
return nil
}
if f.CamelCase {
fieldName = strings.Join(camelcase.Split(fieldName), "-")
}
switch {
case field.Kind() == reflect.Struct && !implementsTextUnmarshaler(field):
for _, ff := range field.Fields() {
flagName := fieldName + "-" + ff.Name()
if f.Flatten {
// first check if it's set or not, because if we have duplicate
// we don't want to break the flag. Panic by giving a readable
// output
flagSet.VisitAll(func(fl *flag.Flag) {
if strings.ToLower(ff.Name()) == fl.Name {
// already defined
panic(fmt.Sprintf("flag '%s' is already defined in outer struct", fl.Name))
}
})
flagName = ff.Name()
}
if err := f.processField(flagSet, flagName, ff); err != nil {
return err
}
}
case field.Kind() == reflect.Ptr:
field.InitElem()
return f.processField(flagSet, fieldName, field)
default:
// Add custom prefix to the flag if it's set
if f.Prefix != "" {
fieldName = f.Prefix + "-" + fieldName
}
flagSet.Var(newFieldValue(field), flagName(fieldName), flagUsage(fieldName))
}
return nil
}