mapstructure

Documentation

Index

• func Decode(input interface{}, output interface{}) error
• func DecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error
• func WeakDecode(input, output interface{}) error
• func WeakDecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error
• type DecodeHookFunc
• type DecodeHookFuncKind
• type DecodeHookFuncType
• type DecodeHookFuncValue
• type Decoder
  • func NewDecoder(config *DecoderConfig) (*Decoder, error)
  • func NewDecoderJson(input interface{}, output interface{}) (*Decoder, error)
  • func (d *Decoder) Decode(input interface{}) error
• type DecoderConfig
• type Error
  • func (e *Error) Error() string
  • func (e *Error) WrappedErrors() []error
• type Metadata

Functions

func Decode

func Decode(input interface{}, output interface{}) error

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 DecodeMetadata

func DecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error

DecodeMetadata is the same as Decode, but is shorthand to enable metadata collection. See DecoderConfig for more info.

func WeakDecode

func WeakDecode(input, output interface{}) error

WeakDecode is the same as Decode but is shorthand to enable WeaklyTypedInput. See DecoderConfig for more info.

func WeakDecodeMetadata

func WeakDecodeMetadata(input interface{}, output interface{}, metadata *Metadata) error

WeakDecodeMetadata is the same as Decode, but is shorthand to enable both WeaklyTypedInput and metadata collection. See DecoderConfig for more info.

Types

type DecodeHookFunc

type DecodeHookFunc interface{}

type DecodeHookFuncKind

type DecodeHookFuncKind func(reflect.Kind, reflect.Kind, interface{}) (interface{}, error)

DecodeHookFuncKind is a DecodeHookFunc which knows only the Kinds of the source and target types.

type DecodeHookFuncType

type DecodeHookFuncType func(reflect.Type, reflect.Type, interface{}) (interface{}, error)

DecodeHookFuncType is a DecodeHookFunc which has complete information about the source and target types.

type DecodeHookFuncValue

type DecodeHookFuncValue func(from reflect.Value, to reflect.Value) (interface{}, error)

DecodeHookFuncValue is a DecodeHookFunc which has complete access to both the source and target values.

type Decoder

type Decoder struct {
	// contains filtered or unexported fields
}

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.

func NewDecoder

func NewDecoder(config *DecoderConfig) (*Decoder, error)

NewDecoder returns a new decoder for the given configuration. Once a decoder has been returned, the same configuration must not be used again.

func NewDecoderJson

func NewDecoderJson(input interface{}, output interface{}) (*Decoder, error)

func (*Decoder) Decode

func (d *Decoder) Decode(input interface{}) error

Decode decodes the given raw interface to the target pointer specified by the configuration.

type DecoderConfig

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
}

DecoderConfig is the configuration that is used to create a new decoder and allows customization of various aspects of decoding.

type Error

type Error struct {
	Errors []string
}

Error implements the error interface and can represents multiple errors that occur in the course of a single decode.

func (*Error) Error

func (e *Error) Error() string

func (*Error) WrappedErrors

func (e *Error) WrappedErrors() []error

WrappedErrors implements the errwrap.Wrapper interface to make this return value more useful with the errwrap and go-multierror libraries.

type Metadata

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
}

Metadata contains information about decoding a structure that is tedious or difficult to get otherwise.