Dart supports multiple [outputs types](https://dart.dev/tools/dart-compile#types-of-output), you can choose between them using `dartOutputType` (defaults to `exe`). If you want to override the binaries path or the source path they come from, you can use `dartEntryPoints`. Outputs that require a runtime will automatically be wrapped with the relevant runtime (`dartaotruntime` for `aot-snapshot`, `dart run` for `jit-snapshot` and `kernel`, `node` for `js`), this can be overridden through `dartRuntimeCommand`.

```nix
{
  lib,
  buildDartApplication,
  fetchFromGitHub,
}:

buildDartApplication rec {
  pname = "dart-sass";
  version = "1.62.1";

  src = fetchFromGitHub {
    owner = "sass";
    repo = "dart-sass";
    tag = version;
    hash = "sha256-U6enz8yJcc4Wf8m54eYIAnVg/jsGi247Wy8lp1r1wg4=";
  };

  pubspecLock = lib.importJSON ./pubspec.lock.json;
}
```

### Patching dependencies {#ssec-dart-applications-patching-dependencies}

Some Dart packages require patches or build environment changes. Package derivations can be customised with the `customSourceBuilders` argument.

A collection of such customisations can be found in Nixpkgs, in the `development/compilers/dart/package-source-builders` directory.

This allows fixes for packages to be shared between all applications that use them. It is strongly recommended to add to this collection instead of including fixes in your application derivation itself.

### Running executables from dev_dependencies {#ssec-dart-applications-build-tools}

Many Dart applications require executables from the `dev_dependencies` section in `pubspec.yaml` to be run before building them.

This can be done in `preBuild`, in one of two ways:

1. Packaging the tool with `buildDartApplication`, adding it to Nixpkgs, and running it like any other application
2. Running the tool from the package cache

Of these methods, the first is recommended when using a tool that does not need
to be of a specific version.

For the second method, the `packageRun` function from the `dartConfigHook` can be used.
This is an alternative to `dart run` that does not rely on Pub.

e.g., for `build_runner`:

```bash
packageRun build_runner build
```

Do _not_ use `dart run <package_name>`, as this will attempt to download dependencies with Pub.

### Usage with nix-shell {#ssec-dart-applications-nix-shell}

#### Using dependencies from the Nix store {#ssec-dart-applications-nix-shell-deps}