dotenvy-derive

Proc macro that derives struct initialization from .env files at compile time via dotenv_codegen.

Usage

Add to Cargo.toml:

[dependencies]
dotenvy-derive = "0.15"
dotenvy_macro = "0.15"

impl Default (standard)

use dotenvy_derive::Bind;

#[derive(Bind)]
pub struct ZoomConfig {
    #[dotenv("ZOOM_APP_KEY")]
    pub app_key: &'static str,
    #[dotenv("ZOOM_APP_SECRET")]
    pub app_secret: &'static str,
}

let config = ZoomConfig::default();

Generates:

impl Default for ZoomConfig {
    fn default() -> Self {
        ZoomConfig {
            app_key: ::dotenv_codegen::dotenv!("ZOOM_APP_KEY"),
            app_secret: ::dotenv_codegen::dotenv!("ZOOM_APP_SECRET"),
        }
    }
}

pub const INSTANCE (static)

Add #[dotenv_static] to emit a compile-time constant instead:

use dotenvy_derive::Bind;

#[derive(Bind)]
#[dotenv_static]
pub struct ZoomConfig {
    #[dotenv("ZOOM_APP_KEY")]
    pub app_key: &'static str,
    #[dotenv("ZOOM_APP_SECRET")]
    pub app_secret: &'static str,
}

// Use in const context:
pub const CONFIG: AppConfig = AppConfig {
    zoom: ZoomConfig::INSTANCE,
};

Generates:

impl ZoomConfig {
    pub const INSTANCE: ZoomConfig = ZoomConfig {
        app_key: ::dotenv_codegen::dotenv!("ZOOM_APP_KEY"),
        app_secret: ::dotenv_codegen::dotenv!("ZOOM_APP_SECRET"),
    };
}

Requirements

• All fields must be &'static str — dotenv! returns &'static str
• A .env file must exist at the crate root at build time
• Consumer crate must depend on dotenv_codegen directly

Error handling

The macro emits a compile error for:

• Non-struct types (enums, unions)
• Tuple or unit structs
• Fields missing #[dotenv("VAR_NAME")]
• Malformed #[dotenv(...)] attribute

License

MIT