Apply programmatic overrides

Use WithOverrides when your program must change configuration after reading a file.

loader, err := fuda.New().
    FromFile("config.yaml").
    WithOverrides(map[string]any{
        "server.port": 9090,
    }).
    Build()

This example changes the nested YAML value at server.port before Fuda decodes the source into your struct.

Know the order

Fuda processes template content first. It applies overrides to the rendered source before YAML decoding. After decoding, an env tag can still replace the overridden field.

type Config struct {
    Port int `yaml:"port" env:"APP_PORT"`
}

With APP_PORT=8080, the environment value wins over an override that set port to 9090.

Use overrides for values your program controls, such as a test port or a command-line option. Keep operator-controlled configuration in files or environment variables.

Next step

Add dynamic defaults or custom conversions.