Documentation
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Overview ¶
Package mapstructurev2 provides decode hooks for DcValue[T] fields that target github.com/go-viper/mapstructure/v2, the actively maintained mapstructure fork.
Several config loaders decode into structs through this fork:
- koanf v2 (github.com/knadh/koanf/v2): pass HookFunc() in the DecoderConfig of koanf.UnmarshalConf.
- viper >= 1.18 (github.com/spf13/viper): pass HookFunc() via viper.DecodeHook.
- OpenTelemetry Collector and other tools built on go-viper/mapstructure/v2.
The hooks behave identically to the sibling package github.com/PapaDanielVi/poya/hooks, which targets the older github.com/mitchellh/mapstructure (v1) used by viper < 1.18. Use whichever matches your loader's mapstructure dependency.
koanf usage:
k := koanf.New(".")
// ... load providers/parsers into k ...
err := k.UnmarshalWithConf("", &cfg, koanf.UnmarshalConf{
Tag: "koanf",
DecoderConfig: &mapstructure.DecoderConfig{
DecodeHook: mapstructurev2.HookFunc(),
Result: &cfg,
},
})
viper (>= 1.18) usage:
err := viper.Unmarshal(&cfg, viper.DecodeHook(mapstructurev2.HookFunc()))
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func HookFunc ¶
func HookFunc() mapstructure.DecodeHookFunc
HookFunc returns a mapstructure.DecodeHookFunc that detects target fields of type *poya.DcValue[T] and initializes them from the decoded source data.
It handles every DcValue kind:
- scalar T: the source value is converted, or parsed when it arrives as a string (common with env vars and flat config), into T.
- time.Duration T: string sources like "30s" are parsed with time.ParseDuration.
- time.Time T: string sources in RFC3339 are parsed with time.Parse.
- any T whose pointer implements encoding.TextUnmarshaler: parses itself.
- struct T: a map source (typically from YAML) is JSON-encoded and decoded into T.
- slice T: a slice source is JSON-encoded and decoded into the slice.
func HookFuncValue ¶
func HookFuncValue() mapstructure.DecodeHookFuncValue
HookFuncValue returns a mapstructure.DecodeHookFuncValue for use with ComposeDecodeHookFunc or when the value hook type is needed.
func JSONStringHookFunc ¶
func JSONStringHookFunc() mapstructure.DecodeHookFunc
JSONStringHookFunc returns a hook that decodes a JSON string source (for example a struct or array stored as a single config value) into a struct or slice DcValue[T]. Non-matching values pass through unchanged.
func StringToDcValueHookFunc ¶
func StringToDcValueHookFunc() mapstructure.DecodeHookFunc
StringToDcValueHookFunc returns a hook that only handles string sources targeting a DcValue[T] with a non-string scalar T (int, uint, float, bool, complex, time.Duration, time.Time). It is the composable piece used when configuration arrives entirely as strings, such as from environment variables. Non-matching values pass through unchanged so it can be combined with other hooks via mapstructure.ComposeDecodeHookFunc.
Types ¶
This section is empty.
Source Files