Configuration files

Fuda reads YAML or JSON from a file, reader, or byte slice. Use a yaml tag when the file key should differ from the Go field name.

type Config struct {
    Host string `yaml:"host" default:"localhost"`
    Port int    `yaml:"port" default:"8080"`
}

host: 0.0.0.0
port: 3000

Load the file with the builder:

loader, err := fuda.New().FromFile("config.yaml").Build()
if err != nil {
    return err
}

var cfg Config
if err := loader.Load(&cfg); err != nil {
    return err
}

Fuda matches YAML keys to the yaml tags and decodes them into the struct. An ordinary file value wins over the field's default value.

Missing and explicit values

When port is missing, the default:"8080" tag supplies the value. An explicit zero value remains an explicit choice:

port: 0

Fuda keeps 0 instead of replacing it with 8080. The same rule applies to false and an empty string.

YAML null counts as absent for default handling. With port: null, Fuda applies default:"8080".

Next step

Use defaults to give missing values a useful starting point.