Struct tags

Everything about a field is described by its struct tags: where the value comes from, how it is documented and how it is parsed.

type Config struct {
    Token string   `yaml:"token" env:"TOKEN" initial:"dev" doc:"API token" hidden:"true"`
    Hosts []string `yaml:"hosts" env:"HOSTS" separator:";"`
}

Driver tags

Every driver reads its own tag, the value of the tag is the name of the value in the source of the driver.

Driver	Tag	Value
tag	any, set in tag.New	the default value itself
yaml	yaml	key in the file
json	json	key in the file
toml	toml	key in the file
env	env	name of the environment variable
flag	flag	name of the command line flag

A field without the tag of the driver is skipped by this driver.

Common tags

Tag	Description
doc:"text"	description of the field for GenDoc
merge:"true"	slices and maps from several drivers are merged instead of replaced, see Several drivers
hidden:"true"	the value is masked in logs and is not shown in GenDoc, use it for secrets; see also the Secret type
required:"true"	Parse returns an error if the field has no value, see Required fields
separator:";"	separator of slice, array and map items in string values, , by default
kvseparator:"="	separator of map key and value in string values, : by default

See Supported types for the syntax of string values.