func ExampleGetFieldTag() {
s := MyStruct{}
tag, err := reflections.GetFieldTag(s, "FirstField", "matched")
if err != nil {
log.Fatal(err)
}
fmt.Println(tag)
tag, err = reflections.GetFieldTag(s, "ThirdField", "unmatched")
if err != nil {
log.Fatal(err)
}
fmt.Println(tag)
}
// ProcessCopy processes copy.
func (dc *DeepCopier) ProcessCopy() error {
fields, _ := reflections.Fields(dc.Tagged)
for _, field := range fields {
fieldOptions := &FieldOptions{
SourceField: field,
DestinationField: field,
WithContext: false,
Skip: false,
}
tagOptions, _ := reflections.GetFieldTag(dc.Tagged, field, TagName)
if tagOptions != "" {
opts := dc.GetTagOptions(tagOptions)
if _, ok := opts[FieldOptionName]; ok {
fieldName := opts[FieldOptionName]
if !dc.Reversed {
fieldOptions.SourceField = fieldName
} else {
fieldOptions.DestinationField = fieldName
}
}
if _, ok := opts[ContextOptionName]; ok {
fieldOptions.WithContext = true
}
if _, ok := opts[SkipOptionName]; ok {
fieldOptions.Skip = true
}
}
if err := dc.SetField(fieldOptions); err != nil {
return err
}
}
return nil
}
func (t *MyTools) GetValueByNamespace(object interface{}, ns []string) interface{} {
// current level of namespace
current := ns[0]
fields, err := reflections.Fields(object)
if err != nil {
fmt.Printf("Could not return fields for object{%v}\n", object)
return nil
}
for _, field := range fields {
tag, err := reflections.GetFieldTag(object, field, "json")
if err != nil {
fmt.Printf("Could not find tag for field{%s}\n", field)
return nil
}
// remove omitempty from tag
tag = strings.Replace(tag, ",omitempty", "", -1)
if tag == current {
val, _ := reflections.GetField(object, field)
// handling of special cases for slice and map
switch reflect.TypeOf(val).Kind() {
case reflect.Slice:
idx, _ := strconv.Atoi(ns[1])
val := reflect.ValueOf(val)
if val.Index(idx).Kind() == reflect.Struct {
return t.GetValueByNamespace(val.Index(idx).Interface(), ns[2:])
} else {
return val.Index(idx).Interface()
}
case reflect.Map:
key := ns[1]
// try uint64 map (memory_stats case)
if vi, ok := val.(map[string]uint64); ok {
return vi[key]
}
// try with hugetlb map (hugetlb_stats case)
val := reflect.ValueOf(val)
kval := reflect.ValueOf(key)
if reflect.TypeOf(val.MapIndex(kval).Interface()).Kind() == reflect.Struct {
return t.GetValueByNamespace(val.MapIndex(kval).Interface(), ns[2:])
}
default:
// last ns, return value found
if len(ns) == 1 {
return val
} else {
// or go deeper
return t.GetValueByNamespace(val, ns[1:])
}
}
}
}
return nil
}
// ProcessCopy processes copy.
func (dc *DeepCopier) ProcessCopy() error {
fields := []string{}
val := reflect.ValueOf(dc.Tagged).Elem()
for i := 0; i < val.NumField(); i++ {
typ := val.Type().Field(i)
// Embedded struct
if typ.Anonymous {
f, _ := reflections.Fields(val.Field(i).Interface())
fields = append(fields, f...)
} else {
fields = append(fields, typ.Name)
}
}
for _, field := range fields {
fieldOptions := &FieldOptions{
SourceField: field,
DestinationField: field,
WithContext: false,
Skip: false,
}
tagOptions, _ := reflections.GetFieldTag(dc.Tagged, field, TagName)
if tagOptions != "" {
opts := dc.GetTagOptions(tagOptions)
if _, ok := opts[FieldOptionName]; ok {
fieldName := opts[FieldOptionName]
if !dc.Reversed {
fieldOptions.SourceField = fieldName
} else {
fieldOptions.DestinationField = fieldName
}
}
if _, ok := opts[ContextOptionName]; ok {
fieldOptions.WithContext = true
}
if _, ok := opts[SkipOptionName]; ok {
fieldOptions.Skip = true
}
}
if err := dc.SetField(fieldOptions); err != nil {
return err
}
}
return nil
}
// createFieldInfos creates the fieldInfos for a struct s.
// Only information from the struct (headerName, fieldName and kind) is available,
// all field positions are initialized with an invalid value of -1
func createFieldInfos(s interface{}) (fieldInfos, error) {
if reflect.TypeOf(s).Kind() != reflect.Struct {
return nil, ErrNoStruct
}
fieldInfos := []fieldInfo{}
headerNameMap := map[string]interface{}{} // to detect duplicate csv tag names
fieldNames, err := reflections.Fields(s)
if err != nil {
return nil, err
}
for _, fieldName := range fieldNames {
headerName, err := reflections.GetFieldTag(s, fieldName, "csv")
if err != nil {
return nil, err
}
// csv fieldtags that contain a dash are ignored
if strings.Contains(headerName, "-") {
continue
}
if _, ok := headerNameMap[headerName]; ok {
return nil, fmt.Errorf("duplicate csv tag name: %s", headerName)
}
headerNameMap[headerName] = nil
kind, err := reflections.GetFieldKind(s, fieldName)
if err != nil {
return nil, err
}
if len(headerName) == 0 {
return nil, fmt.Errorf("empty csv tag for field: %s", fieldName)
}
fieldInfos = append(fieldInfos, fieldInfo{
headerName: headerName,
fieldName: fieldName,
position: -1,
kind: kind,
})
}
return fieldInfos, nil
}
func formTagFromField(fieldName string, target interface{}) (string, error) {
fieldKind, err := reflections.GetFieldKind(target, fieldName)
f, _ := reflections.GetField(target, fieldName)
fmt.Printf("Field %v\n", f)
if err != nil {
return "", err
}
choices, _ := reflections.GetFieldTag(target, fieldName, "choices")
switch fieldKind {
case reflect.String:
if choices != "" {
return "list", nil
}
return "input", nil
case reflect.Slice:
return "checkbox", nil
case reflect.Bool:
return "confirm", nil
}
return "", nil
}
// Reflects on the values in the commandLineOptions structure, and fills it
// with values either from the command line, or from the ENV.
func parseArgs(opts *commandLineOptions, args []string) {
// Create a flag set for args
flags := flag.NewFlagSet(commandLineName, flag.ExitOnError)
// Get the fields for the strucutre
fields, _ := reflections.Fields(opts)
// Loop through each field of the structure, and define a flag for it
for i := 0; i < len(fields); i++ {
fieldName := fields[i]
flagName, _ := reflections.GetFieldTag(opts, fieldName, "flag")
fieldKind, _ := reflections.GetFieldKind(opts, fieldName)
if fieldKind == reflect.String {
flags.String(flagName, "", "")
} else if fieldKind == reflect.Bool {
flags.Bool(flagName, false, "")
} else {
exitAndError(fmt.Sprintf("Could not create flag for %s", fieldName))
}
}
// Define our custom usage text
flags.Usage = func() {
fmt.Printf("%s\n", commandLineUsage)
}
// Search the args until we find a "--", which signifies the user has started
// defining options.
var argumentFlags []string
started := false
for i := 0; i < len(args); i++ {
if strings.HasPrefix(args[i], "--") {
started = true
}
if started {
argumentFlags = append(argumentFlags, args[i])
}
}
// Now parse the flags
flags.Parse(argumentFlags)
// Now the flag set has been populated with values, retrieve them and
// set them (or use the ENV variable if empty)
for i := 0; i < len(fields); i++ {
fieldName := fields[i]
fieldKind, _ := reflections.GetFieldKind(opts, fieldName)
// Grab the flags we need
flagName, _ := reflections.GetFieldTag(opts, fieldName, "flag")
envName, _ := reflections.GetFieldTag(opts, fieldName, "env")
required, _ := reflections.GetFieldTag(opts, fieldName, "required")
// Grab the value from the flag
value := flags.Lookup(flagName).Value.String()
// If the value of the flag is empty, try the ENV
if value == "" {
value = os.Getenv(envName)
}
// Do validation
if required == "true" && value == "" {
exitAndError(fmt.Sprintf("missing %s", flagName))
}
// Set the value in the right way
if fieldKind == reflect.String {
reflections.SetField(opts, fieldName, value)
} else if fieldKind == reflect.Bool {
// The bool is converted to a string above
if value == "true" {
reflections.SetField(opts, fieldName, true)
} else {
reflections.SetField(opts, fieldName, false)
}
} else {
exitAndError(fmt.Sprintf("Could not set value of %s", fieldName))
}
}
}
// Loads the config from the CLI and config files that are present.
func (l *Loader) Load() error {
// Try and find a config file, either passed in the command line using
// --config, or in one of the default configuration file paths.
if l.CLI.String("config") != "" {
file := File{Path: l.CLI.String("config")}
// Because this file was passed in manually, we should throw an error
// if it doesn't exist.
if file.Exists() {
l.File = &file
} else {
return fmt.Errorf("A configuration file could not be found at: %s", file.AbsolutePath())
}
} else if len(l.DefaultConfigFilePaths) > 0 {
for _, path := range l.DefaultConfigFilePaths {
file := File{Path: path}
// If the config file exists, save it to the loader and
// don't bother checking the others.
if file.Exists() {
l.File = &file
break
}
}
}
// If a file was found, then we should load it
if l.File != nil {
// Attempt to load the config file we've found
if err := l.File.Load(); err != nil {
return err
}
}
// Now it's onto actually setting the fields. We start by getting all
// the fields from the configuration interface
var fields []string
fields, _ = reflections.Fields(l.Config)
// Loop through each of the fields, and look for tags and handle them
// appropriately
for _, fieldName := range fields {
// Start by loading the value from the CLI context if the tag
// exists
cliName, _ := reflections.GetFieldTag(l.Config, fieldName, "cli")
if cliName != "" {
// Load the value from the CLI Context
err := l.setFieldValueFromCLI(fieldName, cliName)
if err != nil {
return err
}
}
// Are there any normalizations we need to make?
normalization, _ := reflections.GetFieldTag(l.Config, fieldName, "normalize")
if normalization != "" {
// Apply the normalization
err := l.normalizeField(fieldName, normalization)
if err != nil {
return err
}
}
// Check for field deprecation
deprecationError, _ := reflections.GetFieldTag(l.Config, fieldName, "deprecated")
if deprecationError != "" {
// If the deprecated field's value isn't emtpy, then we
// return the deprecation error message.
if !l.fieldValueIsEmpty(fieldName) {
return fmt.Errorf(deprecationError)
}
}
// Perform validations
validationRules, _ := reflections.GetFieldTag(l.Config, fieldName, "validate")
if validationRules != "" {
// Determine the label for the field
label, _ := reflections.GetFieldTag(l.Config, fieldName, "label")
if label == "" {
// Use the cli name if it exists, but if it
// doesn't, just default to the structs field
// name. Not great, but works!
if cliName != "" {
label = cliName
} else {
label = fieldName
}
}
// Validate the fieid, and if it fails, return it's
// error.
err := l.validateField(fieldName, label, validationRules)
if err != nil {
return err
}
}
}
return nil
}
func reflectField(fieldName string, target interface{}) (Field, error) {
formTag, err := reflections.GetFieldTag(target, fieldName, "form")
if err != nil {
return nil, err
}
if formTag == "" {
s, e := formTagFromField(fieldName, target)
if e != nil || s == "" {
return nil, e
}
formTag = s
}
if !validFieldType(fieldName, target, formTag) {
return nil, fmt.Errorf("target field %s : %s", fieldName, formTag)
}
var message, choicesString string
var choices []string
message, err = reflections.GetFieldTag(target, fieldName, "message")
if err != nil {
return nil, err
}
if message == "" {
message = fieldName
}
choicesString, err = reflections.GetFieldTag(target, fieldName, "choices")
if err != nil {
return nil, err
}
if choicesString != "" {
choices = strings.Split(choicesString, ",")
for i, c := range choices {
choices[i] = strings.Trim(c, " ")
}
}
var field Field
switch formTag {
case "input":
field = &Input{
Name: fieldName,
Message: message,
}
case "confirm":
field = &Confirm{
Name: fieldName,
Message: message,
}
case "password":
field = &Password{
Name: fieldName,
Message: message,
}
case "list":
field = &List{
Name: fieldName,
Message: message,
Choices: choices,
}
case "checkbox":
field = &Checkbox{
Name: fieldName,
Message: message,
Choices: choices,
}
}
return field, nil
}