// Package mapstructure exposes functionality to convert one arbitrary
// Go type into another, typically to convert a map[string]interface{}
// into a native Go structure.
//
// The Go structure can be arbitrarily complex, containing slices,
// other structs, etc. and the decoder will properly decode nested
// maps and so on into the proper structures in the native Go struct.
// See the examples to see what the decoder is capable of.
//
// The simplest function to start with is Decode.
//
// Field Tags
//
// When decoding to a struct, mapstructure will use the field name by
// default to perform the mapping. For example, if a struct has a field
// "Username" then mapstructure will look for a key in the source value
// of "username" (case insensitive).
//
// type User struct {
// Username string
// }
//
// You can change the behavior of mapstructure by using struct tags.
// The default struct tag that mapstructure looks for is "mapstructure"
// but you can customize it using DecoderConfig.
//
// Renaming Fields
//
// To rename the key that mapstructure looks for, use the "mapstructure"
// tag and set a value directly. For example, to change the "username" example
// above to "user":
//
// type User struct {
// Username string `mapstructure:"user"`
// }
//
// Embedded Structs and Squashing
//
// Embedded structs are treated as if they're another field with that name.
// By default, the two structs below are equivalent when decoding with
// mapstructure:
//
// type Person struct {
// Name string
// }
//
// type Friend struct {
// Person
// }
//
// type Friend struct {
// Person Person
// }
//
// This would require an input that looks like below:
//
// map[string]interface{}{
// "person": map[string]interface{}{"name": "alice"},
// }
//
// If your "person" value is NOT nested, then you can append ",squash" to
// your tag value and mapstructure will treat it as if the embedded struct
// were part of the struct directly. Example:
//
// type Friend struct {
// Person `mapstructure:",squash"`
// }
//
// Now the following input would be accepted:
//
// map[string]interface{}{
// "name": "alice",
// }
//
// When decoding from a struct to a map, the squash tag squashes the struct
// fields into a single map. Using the example structs from above:
//
// Friend{Person: Person{Name: "alice"}}
//
// Will be decoded into a map:
//
// map[string]interface{}{
// "name": "alice",
// }
//
// DecoderConfig has a field that changes the behavior of mapstructure
// to always squash embedded structs.
//
// Remainder Values
//
// If there are any unmapped keys in the source value, mapstructure by
// default will silently ignore them. You can error by setting ErrorUnused
// in DecoderConfig. If you're using Metadata you can also maintain a slice
// of the unused keys.
//
// You can also use the ",remain" suffix on your tag to collect all unused
// values in a map. The field with this tag MUST be a map type and should
// probably be a "map[string]interface{}" or "map[interface{}]interface{}".
// See example below:
//
// type Friend struct {
// Name string
// Other map[string]interface{} `mapstructure:",remain"`
// }
//
// Given the input below, Other would be populated with the other
// values that weren't used (everything but "name"):
//
// map[string]interface{}{
// "name": "bob",
// "address": "123 Maple St.",
// }
//
// Omit Empty Values
//
// When decoding from a struct to any other value, you may use the
// ",omitempty" suffix on your tag to omit that value if it equates to
// the zero value. The zero value of all types is specified in the Go
// specification.
//
// For example, the zero type of a numeric type is zero ("0"). If the struct
// field value is zero and a numeric type, the field is empty, and it won't
// be encoded into the destination type.
//
// type Source struct {
// Age int `mapstructure:",omitempty"`
// }
//
// Unexported fields
//
// Since unexported (private) struct fields cannot be set outside the package
// where they are defined, the decoder will simply skip them.
//
// For this output type definition:
//
// type Exported struct {
// private string // this unexported field will be skipped
// Public string
// }
//
// Using this map as input:
//
// map[string]interface{}{
// "private": "I will be ignored",
// "Public": "I made it through!",
// }
//
// The following struct will be decoded:
//
// type Exported struct {
// private: "" // field is left with an empty string (zero value)
// Public: "I made it through!"
// }
//
// Other Configuration
//
// mapstructure is highly configurable. See the DecoderConfig struct
// for other features and options that are supported.
package mapstructure
import (
"encoding/json"
"errors"
"fmt"
"reflect"
"sort"
"strconv"
"strings"
)
// DecodeHookFunc is the callback function that can be used for
// data transformations. See "DecodeHook" in the DecoderConfig
// struct.
//
// The type must be one of DecodeHookFuncType, DecodeHookFuncKind, or
// DecodeHookFuncValue.
// Values are a superset of Types (Values can return types), and Types are a
// superset of Kinds (Types can return Kinds) and are generally a richer thing
// to use, but Kinds are simpler if you only need those.
//
// The reason DecodeHookFunc is multi-typed is for backwards compatibility:
// we started with Kinds and then realized Types were the better solution,
// but have a promise to not break backwards compat so we now support
// both.
type DecodeHookFunc interface{}
// DecodeHookFuncType is a DecodeHookFunc which has complete information about
// the source and target types.
type DecodeHookFuncType func(reflect.Type, reflect.Type, interface{}) (interface{}, error)
// DecodeHookFuncKind is a DecodeHookFunc which knows only the Kinds of the
// source and target types.
type DecodeHookFuncKind func(reflect.Kind, reflect.Kind, interface{}) (interface{}, error)
// DecodeHookFuncValue is a DecodeHookFunc which has complete access to both the source and target
// values.
type DecodeHookFuncValue func(from reflect.Value, to reflect.Value) (interface{}, error)
// DecoderConfig is the configuration that is used to create a new decoder
// and allows customization of various aspects of decoding.
type DecoderConfig struct {
// DecodeHook, if set, will be called before any decoding and any
// type conversion (if WeaklyTypedInput is on). This lets you modify
// the values before they're set down onto the resulting struct. The
// DecodeHook is called for every map and value in the input. This means
// that if a struct has embedded fields with squash tags the decode hook
// is called only once with all of the input data, not once for each
// embedded struct.
//
// If an error is returned, the entire decode will fail with that error.
DecodeHook DecodeHookFunc
// If ErrorUnused is true, then it is an error for there to exist
// keys in the original map that were unused in the decoding process
// (extra keys).
ErrorUnused bool
// If ErrorUnset is true, then it is an error for there to exist
// fields in the result that were not set in the decoding process
// (extra fields). This only applies to decoding to a struct. This
// will affect all nested structs as well.
ErrorUnset bool
// ZeroFields, if set to true, will zero fields before writing them.
// For example, a map will be emptied before decoded values are put in
// it. If this is false, a map will be merged.
ZeroFields bool
// If WeaklyTypedInput is true, the decoder will make the following
// "weak" conversions:
//
// - bools to string (true = "1", false = "0")
// - numbers to string (base 10)
// - bools to int/uint (true = 1, false = 0)
// - strings to int/uint (base implied by prefix)
// - int to bool (true if value != 0)
// - string to bool (accepts: 1, t, T, TRUE, true, True, 0, f, F,
// FALSE, false, False. Anything else is an error)
// - empty array = empty map and vice versa
// - negative numbers to overflowed uint values (base 10)
// - slice of maps to a merged map
// - single values are converted to slices if required. Each
// element is weakly decoded. For example: "4" can become []int{4}
// if the target type is an int slice.
//
WeaklyTypedInput bool
// Squash will squash embedded structs. A squash tag may also be
// added to an individual struct field using a tag. For example:
//
// type Parent struct {
// Child `mapstructure:",squash"`
// }
Squash bool
// Metadata is the struct that will contain extra metadata about
// the decoding. If this is nil, then no metadata will be tracked.
Metadata *Metadata
// Result is a pointer to the struct that will contain the decoded
// value.
Result interface{}
// The tag name that mapstructure reads for field names. This
// defaults to "mapstructure"
TagName string
// IgnoreUntaggedFields ignores all struct fields without explicit
// TagName, comparable to `mapstructure:"-"` as default behaviour.
IgnoreUntaggedFields bool
// MatchName is the function used to match the map key to the struct
// field name or tag. Defaults to `strings.EqualFold`. This can be used
// to implement case-sensitive tag values, support snake casing, etc.
MatchName func(mapKey, fieldName string) bool
}
// A Decoder takes a raw interface value and turns it into structured
// data, keeping track of rich error information along the way in case
// anything goes wrong. Unlike the basic top-level Decode method, you can
// more finely control how the Decoder behaves using the DecoderConfig
// structure. The top-level Decode method is just a convenience that sets
// up the most basic Decoder.
type Decoder struct {
config *DecoderConfig
}
// Metadata contains information about decoding a structure that
// is tedious or difficult to get otherwise.
type Metadata struct {
// Keys are the keys of the structure which were successfully decoded
Keys []string
// Unused is a slice of keys that were found in the raw value but
// weren't decoded since there was no matching field in the result interface
Unused []string
// Unset is a slice of field names that were found in the result interface
// but weren't set in the decoding process since there was no matching value
// in the input
Unset []string
}
// Decode takes an input structure and uses reflection to translate it to
// the output structure. output must be a pointer to a map or struct.
func Decode(input interface{}, output interface{}) error {
config := &DecoderConfig{
Metadata: nil,
Result: output,
}
decoder, err := NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(input)
}
// WeakDecode is the same as Decode but is shorthand to enable
// WeaklyTypedInput. See DecoderConfig for more info.
func WeakDecode(input, output interface{}) error {
config := &DecoderConfig{
Metadata: nil,
Result: output,
WeaklyTypedInput: true,
}
decoder, err := NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(input)
}
// DecodeMetadata is the same as Decode, but is shorthand to
// enable metadata collection. See DecoderConfig for more info.
func DecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error {
config := &DecoderConfig{
Metadata: metadata,
Result: output,
}
decoder, err := NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(input)
}
// WeakDecodeMetadata is the same as Decode, but is shorthand to
// enable both WeaklyTypedInput and metadata collection. See
// DecoderConfig for more info.
func WeakDecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error {
config := &DecoderConfig{
Metadata: metadata,
Result: output,
WeaklyTypedInput: true,
}
decoder, err := NewDecoder(config)
if err != nil {
return err
}
return decoder.Decode(input)
}
// NewDecoder returns a new decoder for the given configuration. Once
// a decoder has been returned, the same configuration must not be used
// again.
func NewDecoder(config *DecoderConfig) (*Decoder, error) {
val := reflect.ValueOf(config.Result)
if val.Kind() != reflect.Ptr {
return nil, errors.New("result must be a pointer")
}
val = val.Elem()
if !val.CanAddr() {
return nil, errors.New("result must be addressable (a pointer)")
}
if config.Metadata != nil {
if config.Metadata.Keys == nil {
config.Metadata.Keys = make([]string, 0)
}
if config.Metadata.Unused == nil {
config.Metadata.Unused = make([]string, 0)
}
if config.Metadata.Unset == nil {
config.Metadata.Unset = make([]string, 0)
}
}
if config.TagName == "" {
config.TagName = "mapstructure"
}
if config.MatchName == nil {
config.MatchName = strings.EqualFold
}
result := &Decoder{
config: config,
}
return result, nil
}
// Decode decodes the given raw interface to the target pointer specified
// by the configuration.
func (d *Decoder) Decode(input interface{}) error {
return d.decode("", input, reflect.ValueOf(d.config.Result).Elem())
}
// Decodes an unknown data type into a specific reflection value.
func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) error {
var inputVal reflect.Value
if input != nil {
inputVal = reflect.ValueOf(input)
// We need to check here if input is a typed nil. Typed nils won't
// match the "input == nil" below so we check that here.
if inputVal.Kind() == reflect.Ptr && inputVal.IsNil() {
input = nil
}
}
if input == nil {
// If the data is nil, then we don't set anything, unless ZeroFields is set
// to true.
if d.config.ZeroFields {
outVal.Set(reflect.Zero(outVal.Type()))
if d.config.Metadata != nil && name != "" {
d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
}
}
return nil
}
if !inputVal.IsValid() {
// If the input value is invalid, then we just set the value
// to be the zero value.
outVal.Set(reflect.Zero(outVal.Type()))
if d.config.Metadata != nil && name != "" {
d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
}
return nil
}
if d.config.DecodeHook != nil {
// We have a DecodeHook, so let's pre-process the input.
var err error
input, err = DecodeHookExec(d.config.DecodeHook, inputVal, outVal)
if err != nil {
return fmt.Errorf("error decoding '%s': %s", name, err)
}
}
var err error
outputKind := getKind(outVal)
addMetaKey := true
switch outputKind {
case reflect.Bool:
err = d.decodeBool(name, input, outVal)
case reflect.Interface:
err = d.decodeBasic(name, input, outVal)
case reflect.String:
err = d.decodeString(name, input, outVal)
case reflect.Int:
err = d.decodeInt(name, input, outVal)
case reflect.Uint:
err = d.decodeUint(name, input, outVal)
case reflect.Float32:
err = d.decodeFloat(name, input, outVal)
case reflect.Struct:
err = d.decodeStruct(name, input, outVal)
case reflect.Map:
err = d.decodeMap(name, input, outVal)
case reflect.Ptr:
addMetaKey, err = d.decodePtr(name, input, outVal)
case reflect.Slice:
err = d.decodeSlice(name, input, outVal)
case reflect.Array:
err = d.decodeArray(name, input, outVal)
case reflect.Func:
err = d.decodeFunc(name, input, outVal)
default:
// If we reached this point then we weren't able to decode it
return fmt.Errorf("%s: unsupported type: %s", name, outputKind)
}
// If we reached here, then we successfully decoded SOMETHING, so
// mark the key as used if we're tracking metainput.
if addMetaKey && d.config.Metadata != nil && name != "" {
d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
}
return err
}
// This decodes a basic type (bool, int, string, etc.) and sets the
// value to "data" of that type.
func (d *Decoder) decodeBasic(name string, data interface{}, val reflect.Value) error {
if val.IsValid() && val.Elem().IsValid() {
elem := val.Elem()
// If we can't address this element, then its not writable. Instead,
// we make a copy of the value (which is a pointer and therefore
// writable), decode into that, and replace the whole value.
copied := false
if !elem.CanAddr() {
copied = true
// Make *T
copy := reflect.New(elem.Type())
// *T = elem
copy.Elem().Set(elem)
// Set elem so we decode into it
elem = copy
}
// Decode. If we have an error then return. We also return right
// away if we're not a copy because that means we decoded directly.
if err := d.decode(name, data, elem); err != nil || !copied {
return err
}
// If we're a copy, we need to set te final result
val.Set(elem.Elem())
return nil
}
dataVal := reflect.ValueOf(data)
// If the input data is a pointer, and the assigned type is the dereference
// of that exact pointer, then indirect it so that we can assign it.
// Example: *string to string
if dataVal.Kind() == reflect.Ptr && dataVal.Type().Elem() == val.Type() {
dataVal = reflect.Indirect(dataVal)
}
if !dataVal.IsValid() {
dataVal = reflect.Zero(val.Type())
}
dataValType := dataVal.Type()
if !dataValType.AssignableTo(val.Type()) {
return fmt.Errorf(
"'%s' expected type '%s', got '%s'",
name, val.Type(), dataValType)
}
val.Set(dataVal)
return nil
}
func (d *Decoder) decodeString(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataKind := getKind(dataVal)
converted := true
switch {
case dataKind == reflect.String:
val.SetString(dataVal.String())
case dataKind == reflect.Bool && d.config.WeaklyTypedInput:
if dataVal.Bool() {
val.SetString("1")
} else {
val.SetString("0")
}
case dataKind == reflect.Int && d.config.WeaklyTypedInput:
val.SetString(strconv.FormatInt(dataVal.Int(), 10))
case dataKind == reflect.Uint && d.config.WeaklyTypedInput:
val.SetString(strconv.FormatUint(dataVal.Uint(), 10))
case dataKind == reflect.Float32 && d.config.WeaklyTypedInput:
val.SetString(strconv.FormatFloat(dataVal.Float(), 'f', -1, 64))
case dataKind == reflect.Slice && d.config.WeaklyTypedInput,
dataKind == reflect.Array && d.config.WeaklyTypedInput:
dataType := dataVal.Type()
elemKind := dataType.Elem().Kind()
switch elemKind {
case reflect.Uint8:
var uints []uint8
if dataKind == reflect.Array {
uints = make([]uint8, dataVal.Len(), dataVal.Len())
for i := range uints {
uints[i] = dataVal.Index(i).Interface().(uint8)
}
} else {
uints = dataVal.Interface().([]uint8)
}
val.SetString(string(uints))
default:
converted = false
}
default:
converted = false
}
if !converted {
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
return nil
}
func (d *Decoder) decodeInt(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataKind := getKind(dataVal)
dataType := dataVal.Type()
switch {
case dataKind == reflect.Int:
val.SetInt(dataVal.Int())
case dataKind == reflect.Uint:
val.SetInt(int64(dataVal.Uint()))
case dataKind == reflect.Float32:
val.SetInt(int64(dataVal.Float()))
case dataKind == reflect.Bool && d.config.WeaklyTypedInput:
if dataVal.Bool() {
val.SetInt(1)
} else {
val.SetInt(0)
}
case dataKind == reflect.String && d.config.WeaklyTypedInput:
str := dataVal.String()
if str == "" {
str = "0"
}
i, err := strconv.ParseInt(str, 0, val.Type().Bits())
if err == nil {
val.SetInt(i)
} else {
return fmt.Errorf("cannot parse '%s' as int: %s", name, err)
}
case dataType.PkgPath() == "encoding/json" && dataType.Name() == "Number":
jn := data.(json.Number)
i, err := jn.Int64()
if err != nil {
return fmt.Errorf(
"error decoding json.Number into %s: %s", name, err)
}
val.SetInt(i)
default:
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
return nil
}
func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataKind := getKind(dataVal)
dataType := dataVal.Type()
switch {
case dataKind == reflect.Int:
i := dataVal.Int()
if i < 0 && !d.config.WeaklyTypedInput {
return fmt.Errorf("cannot parse '%s', %d overflows uint",
name, i)
}
val.SetUint(uint64(i))
case dataKind == reflect.Uint:
val.SetUint(dataVal.Uint())
case dataKind == reflect.Float32:
f := dataVal.Float()
if f < 0 && !d.config.WeaklyTypedInput {
return fmt.Errorf("cannot parse '%s', %f overflows uint",
name, f)
}
val.SetUint(uint64(f))
case dataKind == reflect.Bool && d.config.WeaklyTypedInput:
if dataVal.Bool() {
val.SetUint(1)
} else {
val.SetUint(0)
}
case dataKind == reflect.String && d.config.WeaklyTypedInput:
str := dataVal.String()
if str == "" {
str = "0"
}
i, err := strconv.ParseUint(str, 0, val.Type().Bits())
if err == nil {
val.SetUint(i)
} else {
return fmt.Errorf("cannot parse '%s' as uint: %s", name, err)
}
case dataType.PkgPath() == "encoding/json" && dataType.Name() == "Number":
jn := data.(json.Number)
i, err := strconv.ParseUint(string(jn), 0, 64)
if err != nil {
return fmt.Errorf(
"error decoding json.Number into %s: %s", name, err)
}
val.SetUint(i)
default:
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
return nil
}
func (d *Decoder) decodeBool(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataKind := getKind(dataVal)
switch {
case dataKind == reflect.Bool:
val.SetBool(dataVal.Bool())
case dataKind == reflect.Int && d.config.WeaklyTypedInput:
val.SetBool(dataVal.Int() != 0)
case dataKind == reflect.Uint && d.config.WeaklyTypedInput:
val.SetBool(dataVal.Uint() != 0)
case dataKind == reflect.Float32 && d.config.WeaklyTypedInput:
val.SetBool(dataVal.Float() != 0)
case dataKind == reflect.String && d.config.WeaklyTypedInput:
b, err := strconv.ParseBool(dataVal.String())
if err == nil {
val.SetBool(b)
} else if dataVal.String() == "" {
val.SetBool(false)
} else {
return fmt.Errorf("cannot parse '%s' as bool: %s", name, err)
}
default:
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
return nil
}
func (d *Decoder) decodeFloat(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataKind := getKind(dataVal)
dataType := dataVal.Type()
switch {
case dataKind == reflect.Int:
val.SetFloat(float64(dataVal.Int()))
case dataKind == reflect.Uint:
val.SetFloat(float64(dataVal.Uint()))
case dataKind == reflect.Float32:
val.SetFloat(dataVal.Float())
case dataKind == reflect.Bool && d.config.WeaklyTypedInput:
if dataVal.Bool() {
val.SetFloat(1)
} else {
val.SetFloat(0)
}
case dataKind == reflect.String && d.config.WeaklyTypedInput:
str := dataVal.String()
if str == "" {
str = "0"
}
f, err := strconv.ParseFloat(str, val.Type().Bits())
if err == nil {
val.SetFloat(f)
} else {
return fmt.Errorf("cannot parse '%s' as float: %s", name, err)
}
case dataType.PkgPath() == "encoding/json" && dataType.Name() == "Number":
jn := data.(json.Number)
i, err := jn.Float64()
if err != nil {
return fmt.Errorf(
"error decoding json.Number into %s: %s", name, err)
}
val.SetFloat(i)
default:
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
return nil
}
func (d *Decoder) decodeMap(name string, data interface{}, val reflect.Value) error {
valType := val.Type()
valKeyType := valType.Key()
valElemType := valType.Elem()
// By default we overwrite keys in the current map
valMap := val
// If the map is nil or we're purposely zeroing fields, make a new map
if valMap.IsNil() || d.config.ZeroFields {
// Make a new map to hold our result
mapType := reflect.MapOf(valKeyType, valElemType)
valMap = reflect.MakeMap(mapType)
}
// Check input type and based on the input type jump to the proper func
dataVal := reflect.Indirect(reflect.ValueOf(data))
switch dataVal.Kind() {
case reflect.Map:
return d.decodeMapFromMap(name, dataVal, val, valMap)
case reflect.Struct:
return d.decodeMapFromStruct(name, dataVal, val, valMap)
case reflect.Array, reflect.Slice:
if d.config.WeaklyTypedInput {
return d.decodeMapFromSlice(name, dataVal, val, valMap)
}
fallthrough
default:
return fmt.Errorf("'%s' expected a map, got '%s'", name, dataVal.Kind())
}
}
func (d *Decoder) decodeMapFromSlice(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
// Special case for BC reasons (covered by tests)
if dataVal.Len() == 0 {
val.Set(valMap)
return nil
}
for i := 0; i < dataVal.Len(); i++ {
err := d.decode(
name+"["+strconv.Itoa(i)+"]",
dataVal.Index(i).Interface(), val)
if err != nil {
return err
}
}
return nil
}
func (d *Decoder) decodeMapFromMap(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
valType := val.Type()
valKeyType := valType.Key()
valElemType := valType.Elem()
// Accumulate errors
errors := make([]string, 0)
// If the input data is empty, then we just match what the input data is.
if dataVal.Len() == 0 {
if dataVal.IsNil() {
if !val.IsNil() {
val.Set(dataVal)
}
} else {
// Set to empty allocated value
val.Set(valMap)
}
return nil
}
for _, k := range dataVal.MapKeys() {
fieldName := name + "[" + k.String() + "]"
// First decode the key into the proper type
currentKey := reflect.Indirect(reflect.New(valKeyType))
if err := d.decode(fieldName, k.Interface(), currentKey); err != nil {
errors = appendErrors(errors, err)
continue
}
// Next decode the data into the proper type
v := dataVal.MapIndex(k).Interface()
currentVal := reflect.Indirect(reflect.New(valElemType))
if err := d.decode(fieldName, v, currentVal); err != nil {
errors = appendErrors(errors, err)
continue
}
valMap.SetMapIndex(currentKey, currentVal)
}
// Set the built up map to the value
val.Set(valMap)
// If we had errors, return those
if len(errors) > 0 {
return &Error{errors}
}
return nil
}
func (d *Decoder) decodeMapFromStruct(name string, dataVal reflect.Value, val reflect.Value, valMap reflect.Value) error {
typ := dataVal.Type()
for i := 0; i < typ.NumField(); i++ {
// Get the StructField first since this is a cheap operation. If the
// field is unexported, then ignore it.
f := typ.Field(i)
if f.PkgPath != "" {
continue
}
// Next get the actual value of this field and verify it is assignable
// to the map value.
v := dataVal.Field(i)
if !v.Type().AssignableTo(valMap.Type().Elem()) {
return fmt.Errorf("cannot assign type '%s' to map value field of type '%s'", v.Type(), valMap.Type().Elem())
}
tagValue := f.Tag.Get(d.config.TagName)
keyName := f.Name
if tagValue == "" && d.config.IgnoreUntaggedFields {
continue
}
// If Squash is set in the config, we squash the field down.
squash := d.config.Squash && v.Kind() == reflect.Struct && f.Anonymous
v = dereferencePtrToStructIfNeeded(v, d.config.TagName)
// Determine the name of the key in the map
if index := strings.Index(tagValue, ","); index != -1 {
if tagValue[:index] == "-" {
continue
}
// If "omitempty" is specified in the tag, it ignores empty values.
if strings.Index(tagValue[index+1:], "omitempty") != -1 && isEmptyValue(v) {
continue
}
// If "squash" is specified in the tag, we squash the field down.
squash = squash || strings.Index(tagValue[index+1:], "squash") != -1
if squash {
// When squashing, the embedded type can be a pointer to a struct.
if v.Kind() == reflect.Ptr && v.Elem().Kind() == reflect.Struct {
v = v.Elem()
}
// The final type must be a struct
if v.Kind() != reflect.Struct {
return fmt.Errorf("cannot squash non-struct type '%s'", v.Type())
}
}
if keyNameTagValue := tagValue[:index]; keyNameTagValue != "" {
keyName = keyNameTagValue
}
} else if len(tagValue) > 0 {
if tagValue == "-" {
continue
}
keyName = tagValue
}
switch v.Kind() {
// this is an embedded struct, so handle it differently
case reflect.Struct:
x := reflect.New(v.Type())
x.Elem().Set(v)
vType := valMap.Type()
vKeyType := vType.Key()
vElemType := vType.Elem()
mType := reflect.MapOf(vKeyType, vElemType)
vMap := reflect.MakeMap(mType)
// Creating a pointer to a map so that other methods can completely
// overwrite the map if need be (looking at you decodeMapFromMap). The
// indirection allows the underlying map to be settable (CanSet() == true)
// where as reflect.MakeMap returns an unsettable map.
addrVal := reflect.New(vMap.Type())
reflect.Indirect(addrVal).Set(vMap)
err := d.decode(keyName, x.Interface(), reflect.Indirect(addrVal))
if err != nil {
return err
}
// the underlying map may have been completely overwritten so pull
// it indirectly out of the enclosing value.
vMap = reflect.Indirect(addrVal)
if squash {
for _, k := range vMap.MapKeys() {
valMap.SetMapIndex(k, vMap.MapIndex(k))
}
} else {
valMap.SetMapIndex(reflect.ValueOf(keyName), vMap)
}
default:
valMap.SetMapIndex(reflect.ValueOf(keyName), v)
}
}
if val.CanAddr() {
val.Set(valMap)
}
return nil
}
func (d *Decoder) decodePtr(name string, data interface{}, val reflect.Value) (bool, error) {
// If the input data is nil, then we want to just set the output
// pointer to be nil as well.
isNil := data == nil
if !isNil {
switch v := reflect.Indirect(reflect.ValueOf(data)); v.Kind() {
case reflect.Chan,
reflect.Func,
reflect.Interface,
reflect.Map,
reflect.Ptr,
reflect.Slice:
isNil = v.IsNil()
}
}
if isNil {
if !val.IsNil() && val.CanSet() {
nilValue := reflect.New(val.Type()).Elem()
val.Set(nilValue)
}
return true, nil
}
// Create an element of the concrete (non pointer) type and decode
// into that. Then set the value of the pointer to this type.
valType := val.Type()
valElemType := valType.Elem()
if val.CanSet() {
realVal := val
if realVal.IsNil() || d.config.ZeroFields {
realVal = reflect.New(valElemType)
}
if err := d.decode(name, data, reflect.Indirect(realVal)); err != nil {
return false, err
}
val.Set(realVal)
} else {
if err := d.decode(name, data, reflect.Indirect(val)); err != nil {
return false, err
}
}
return false, nil
}
func (d *Decoder) decodeFunc(name string, data interface{}, val reflect.Value) error {
// Create an element of the concrete (non pointer) type and decode
// into that. Then set the value of the pointer to this type.
dataVal := reflect.Indirect(reflect.ValueOf(data))
if val.Type() != dataVal.Type() {
return fmt.Errorf(
"'%s' expected type '%s', got unconvertible type '%s', value: '%v'",
name, val.Type(), dataVal.Type(), data)
}
val.Set(dataVal)
return nil
}
func (d *Decoder) decodeSlice(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataValKind := dataVal.Kind()
valType := val.Type()
valElemType := valType.Elem()
sliceType := reflect.SliceOf(valElemType)
// If we have a non array/slice type then we first attempt to convert.
if dataValKind != reflect.Array && dataValKind != reflect.Slice {
if d.config.WeaklyTypedInput {
switch {
// Slice and array we use the normal logic
case dataValKind == reflect.Slice, dataValKind == reflect.Array:
break
// Empty maps turn into empty slices
case dataValKind == reflect.Map:
if dataVal.Len() == 0 {
val.Set(reflect.MakeSlice(sliceType, 0, 0))
return nil
}
// Create slice of maps of other sizes
return d.decodeSlice(name, []interface{}{data}, val)
case dataValKind == reflect.String && valElemType.Kind() == reflect.Uint8:
return d.decodeSlice(name, []byte(dataVal.String()), val)
// All other types we try to convert to the slice type
// and "lift" it into it. i.e. a string becomes a string slice.
default:
// Just re-try this function with data as a slice.
return d.decodeSlice(name, []interface{}{data}, val)
}
}
return fmt.Errorf(
"'%s': source data must be an array or slice, got %s", name, dataValKind)
}
// If the input value is nil, then don't allocate since empty != nil
if dataValKind != reflect.Array && dataVal.IsNil() {
return nil
}
valSlice := val
if valSlice.IsNil() || d.config.ZeroFields {
// Make a new slice to hold our result, same size as the original data.
valSlice = reflect.MakeSlice(sliceType, dataVal.Len(), dataVal.Len())
}
// Accumulate any errors
errors := make([]string, 0)
for i := 0; i < dataVal.Len(); i++ {
currentData := dataVal.Index(i).Interface()
for valSlice.Len() <= i {
valSlice = reflect.Append(valSlice, reflect.Zero(valElemType))
}
currentField := valSlice.Index(i)
fieldName := name + "[" + strconv.Itoa(i) + "]"
if err := d.decode(fieldName, currentData, currentField); err != nil {
errors = appendErrors(errors, err)
}
}
// Finally, set the value to the slice we built up
val.Set(valSlice)
// If there were errors, we return those
if len(errors) > 0 {
return &Error{errors}
}
return nil
}
func (d *Decoder) decodeArray(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
dataValKind := dataVal.Kind()
valType := val.Type()
valElemType := valType.Elem()
arrayType := reflect.ArrayOf(valType.Len(), valElemType)
valArray := val
if valArray.Interface() == reflect.Zero(valArray.Type()).Interface() || d.config.ZeroFields {
// Check input type
if dataValKind != reflect.Array && dataValKind != reflect.Slice {
if d.config.WeaklyTypedInput {
switch {
// Empty maps turn into empty arrays
case dataValKind == reflect.Map:
if dataVal.Len() == 0 {
val.Set(reflect.Zero(arrayType))
return nil
}
// All other types we try to convert to the array type
// and "lift" it into it. i.e. a string becomes a string array.
default:
// Just re-try this function with data as a slice.
return d.decodeArray(name, []interface{}{data}, val)
}
}
return fmt.Errorf(
"'%s': source data must be an array or slice, got %s", name, dataValKind)
}
if dataVal.Len() > arrayType.Len() {
return fmt.Errorf(
"'%s': expected source data to have length less or equal to %d, got %d", name, arrayType.Len(), dataVal.Len())
}
// Make a new array to hold our result, same size as the original data.
valArray = reflect.New(arrayType).Elem()
}
// Accumulate any errors
errors := make([]string, 0)
for i := 0; i < dataVal.Len(); i++ {
currentData := dataVal.Index(i).Interface()
currentField := valArray.Index(i)
fieldName := name + "[" + strconv.Itoa(i) + "]"
if err := d.decode(fieldName, currentData, currentField); err != nil {
errors = appendErrors(errors, err)
}
}
// Finally, set the value to the array we built up
val.Set(valArray)
// If there were errors, we return those
if len(errors) > 0 {
return &Error{errors}
}
return nil
}
func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value) error {
dataVal := reflect.Indirect(reflect.ValueOf(data))
// If the type of the value to write to and the data match directly,
// then we just set it directly instead of recursing into the structure.
if dataVal.Type() == val.Type() {
val.Set(dataVal)
return nil
}
dataValKind := dataVal.Kind()
switch dataValKind {
case reflect.Map:
return d.decodeStructFromMap(name, dataVal, val)
case reflect.Struct:
// Not the most efficient way to do this but we can optimize later if
// we want to. To convert from struct to struct we go to map first
// as an intermediary.
// Make a new map to hold our result
mapType := reflect.TypeOf((map[string]interface{})(nil))
mval := reflect.MakeMap(mapType)
// Creating a pointer to a map so that other methods can completely
// overwrite the map if need be (looking at you decodeMapFromMap). The
// indirection allows the underlying map to be settable (CanSet() == true)
// where as reflect.MakeMap returns an unsettable map.
addrVal := reflect.New(mval.Type())
reflect.Indirect(addrVal).Set(mval)
if err := d.decodeMapFromStruct(name, dataVal, reflect.Indirect(addrVal), mval); err != nil {
return err
}
result := d.decodeStructFromMap(name, reflect.Indirect(addrVal), val)
return result
default:
return fmt.Errorf("'%s' expected a map, got '%s'", name, dataVal.Kind())
}
}
func (d *Decoder) decodeStructFromMap(name string, dataVal, val reflect.Value) error {
dataValType := dataVal.Type()
if kind := dataValType.Key().Kind(); kind != reflect.String && kind != reflect.Interface {
return fmt.Errorf(
"'%s' needs a map with string keys, has '%s' keys",
name, dataValType.Key().Kind())
}
dataValKeys := make(map[reflect.Value]struct{})
dataValKeysUnused := make(map[interface{}]struct{})
for _, dataValKey := range dataVal.MapKeys() {
dataValKeys[dataValKey] = struct{}{}
dataValKeysUnused[dataValKey.Interface()] = struct{}{}
}
targetValKeysUnused := make(map[interface{}]struct{})
errors := make([]string, 0)
// This slice will keep track of all the structs we'll be decoding.
// There can be more than one struct if there are embedded structs
// that are squashed.
structs := make([]reflect.Value, 1, 5)
structs[0] = val
// Compile the list of all the fields that we're going to be decoding
// from all the structs.
type field struct {
field reflect.StructField
val reflect.Value
}
// remainField is set to a valid field set with the "remain" tag if
// we are keeping track of remaining values.
var remainField *field
fields := []field{}
for len(structs) > 0 {
structVal := structs[0]
structs = structs[1:]
structType := structVal.Type()
for i := 0; i < structType.NumField(); i++ {
fieldType := structType.Field(i)
fieldVal := structVal.Field(i)
if fieldVal.Kind() == reflect.Ptr && fieldVal.Elem().Kind() == reflect.Struct {
// Handle embedded struct pointers as embedded structs.
fieldVal = fieldVal.Elem()
}
// If "squash" is specified in the tag, we squash the field down.
squash := d.config.Squash && fieldVal.Kind() == reflect.Struct && fieldType.Anonymous
remain := false
// We always parse the tags cause we're looking for other tags too
tagParts := strings.Split(fieldType.Tag.Get(d.config.TagName), ",")
for _, tag := range tagParts[1:] {
if tag == "squash" {
squash = true
break
}
if tag == "remain" {
remain = true
break
}
}
if squash {
if fieldVal.Kind() != reflect.Struct {
errors = appendErrors(errors,
fmt.Errorf("%s: unsupported type for squash: %s", fieldType.Name, fieldVal.Kind()))
} else {
structs = append(structs, fieldVal)
}
continue
}
// Build our field
if remain {
remainField = &field{fieldType, fieldVal}
} else {
// Normal struct field, store it away
fields = append(fields, field{fieldType, fieldVal})
}
}
}
// for fieldType, field := range fields {
for _, f := range fields {
field, fieldValue := f.field, f.val
fieldName := field.Name
tagValue := field.Tag.Get(d.config.TagName)
tagValue = strings.SplitN(tagValue, ",", 2)[0]
if tagValue != "" {
fieldName = tagValue
}
rawMapKey := reflect.ValueOf(fieldName)
rawMapVal := dataVal.MapIndex(rawMapKey)
if !rawMapVal.IsValid() {
// Do a slower search by iterating over each key and
// doing case-insensitive search.
for dataValKey := range dataValKeys {
mK, ok := dataValKey.Interface().(string)
if !ok {
// Not a string key
continue
}
if d.config.MatchName(mK, fieldName) {
rawMapKey = dataValKey
rawMapVal = dataVal.MapIndex(dataValKey)
break
}
}
if !rawMapVal.IsValid() {
// There was no matching key in the map for the value in
// the struct. Remember it for potential errors and metadata.
targetValKeysUnused[fieldName] = struct{}{}
continue
}
}
if !fieldValue.IsValid() {
// This should never happen
panic("field is not valid")
}
// If we can't set the field, then it is unexported or something,
// and we just continue onwards.
if !fieldValue.CanSet() {
continue
}
// Delete the key we're using from the unused map so we stop tracking
delete(dataValKeysUnused, rawMapKey.Interface())
// If the name is empty string, then we're at the root, and we
// don't dot-join the fields.
if name != "" {
fieldName = name + "." + fieldName
}
if err := d.decode(fieldName, rawMapVal.Interface(), fieldValue); err != nil {
errors = appendErrors(errors, err)
}
}
// If we have a "remain"-tagged field and we have unused keys then
// we put the unused keys directly into the remain field.
if remainField != nil && len(dataValKeysUnused) > 0 {
// Build a map of only the unused values
remain := map[interface{}]interface{}{}
for key := range dataValKeysUnused {
remain[key] = dataVal.MapIndex(reflect.ValueOf(key)).Interface()
}
// Decode it as-if we were just decoding this map onto our map.
if err := d.decodeMap(name, remain, remainField.val); err != nil {
errors = appendErrors(errors, err)
}
// Set the map to nil so we have none so that the next check will
// not error (ErrorUnused)
dataValKeysUnused = nil
}
if d.config.ErrorUnused && len(dataValKeysUnused) > 0 {
keys := make([]string, 0, len(dataValKeysUnused))
for rawKey := range dataValKeysUnused {
keys = append(keys, rawKey.(string))
}
sort.Strings(keys)
err := fmt.Errorf("'%s' has invalid keys: %s", name, strings.Join(keys, ", "))
errors = appendErrors(errors, err)
}
if d.config.ErrorUnset && len(targetValKeysUnused) > 0 {
keys := make([]string, 0, len(targetValKeysUnused))
for rawKey := range targetValKeysUnused {
keys = append(keys, rawKey.(string))
}
sort.Strings(keys)
err := fmt.Errorf("'%s' has unset fields: %s", name, strings.Join(keys, ", "))
errors = appendErrors(errors, err)
}
if len(errors) > 0 {
return &Error{errors}
}
// Add the unused keys to the list of unused keys if we're tracking metadata
if d.config.Metadata != nil {
for rawKey := range dataValKeysUnused {
key := rawKey.(string)
if name != "" {
key = name + "." + key
}
d.config.Metadata.Unused = append(d.config.Metadata.Unused, key)
}
for rawKey := range targetValKeysUnused {
key := rawKey.(string)
if name != "" {
key = name + "." + key
}
d.config.Metadata.Unset = append(d.config.Metadata.Unset, key)
}
}
return nil
}
func isEmptyValue(v reflect.Value) bool {
switch getKind(v) {
case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
return v.Len() == 0
case reflect.Bool:
return !v.Bool()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return v.Uint() == 0
case reflect.Float32, reflect.Float64:
return v.Float() == 0
case reflect.Interface, reflect.Ptr:
return v.IsNil()
}
return false
}
func getKind(val reflect.Value) reflect.Kind {
kind := val.Kind()
switch {
case kind >= reflect.Int && kind <= reflect.Int64:
return reflect.Int
case kind >= reflect.Uint && kind <= reflect.Uint64:
return reflect.Uint
case kind >= reflect.Float32 && kind <= reflect.Float64:
return reflect.Float32
default:
return kind
}
}
func isStructTypeConvertibleToMap(typ reflect.Type, checkMapstructureTags bool, tagName string) bool {
for i := 0; i < typ.NumField(); i++ {
f := typ.Field(i)
if f.PkgPath == "" && !checkMapstructureTags { // check for unexported fields
return true
}
if checkMapstructureTags && f.Tag.Get(tagName) != "" { // check for mapstructure tags inside
return true
}
}
return false
}
func dereferencePtrToStructIfNeeded(v reflect.Value, tagName string) reflect.Value {
if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
return v
}
deref := v.Elem()
derefT := deref.Type()
if isStructTypeConvertibleToMap(derefT, true, tagName) {
return deref
}
return v
}