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site</a></li></ul></li></ul></div></div><main id="page-content"><div id="site-toc--side" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry nav-item"><a class="nav-link" href="#setting-up-build_runner">Setting up build_<wbr>runner</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#using-built-in-commands">Using built-in commands</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#more-information">More information</a></li></ul></div><article><div class="content"><div id="site-content-title"><h1>build_runner</h1></div><div id="site-toc--inline" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry"><a href="#setting-up-build_runner">Setting up build_runner</a></li><li class="toc-entry"><a href="#using-built-in-commands">Using built-in commands</a></li><li class="toc-entry"><a href="#more-information">More information</a></li></ul></div><p>The <a href="https://pub.dev/packages/build_runner">build_runner</a> package provides general-purpose commands for generating files, including testing the generated files or serving both source and generated files. This page explains how to use <code>build_runner</code>. To learn how to use build_runner with a specific package, see the documentation for that package.</p><aside class="alert alert-info"><div class="alert-header"><i class="material-symbols" aria-hidden="true">info</i> <span>Note</span></div><div class="alert-content"><p>If you're a web developer, use the <a href="/tools/webdev"><code>webdev</code> tool</a> to build and serve web apps.</p></div></aside><p>The build_runner commands work with <em>builders</em>鈥攑ackages that use the <a href="https://github.com/dart-lang/build">Dart build system</a> to generate output files from input files. For example, the <a href="https://pub.dev/packages/json_serializable">json_serializable</a> and <a href="https://pub.dev/packages/built_value_generator">built_value_generator</a> packages define builders that generate Dart code.</p><p>Although the Dart build system is a good alternative to reflection (which has performance issues) and macros (which Dart's compilers don't support), it can do more than just read and write Dart code. For example, the <a href="https://pub.dev/packages/sass_builder">sass_builder</a> package implements a builder that generates <code>.css</code> files from <code>.scss</code> and <code>.sass</code> files.</p><div class="header-wrapper"><h2 id="setting-up-build_runner">Setting up build_runner</h2><a class="heading-link" href="#setting-up-build_runner" aria-label="Link to 'Setting up build_runner' section">#</a></div><p>To use build_runner, add a <a href="/tools/pub/dependencies#dev-dependencies">dev dependency</a> on <strong>build_runner</strong> to your app's pubspec:</p> <?code-excerpt "build_runner_usage/pubspec.yaml" from="dev_dependencies" to="build_test" replace="/args.*/# 路路路/g"?> <div class="code-block-wrapper language-yaml"><div class="code-block-body"><span class="code-block-language" title="Language yaml">yaml</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#0468D7">dev_dependencies</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#6E6E70"> # 路路路</span></span> <span class="line"><span style="color:#0468D7"> build_runner</span><span style="color:#222222">: </span><span style="color:#11796D">^2.4.12</span></span> <span class="line"><span style="color:#0468D7"> build_test</span><span style="color:#222222">: </span><span style="color:#11796D">^2.2.2</span></span></code></pre></div></div><p>Depending on <strong>build_test</strong> is optional; do it if you'll be testing your code.</p><p>As usual after <code>pubspec.yaml</code> changes, run <code>dart pub get</code> or <code>dart pub upgrade</code>:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart pub get</span></span></code></pre></div></div><div class="header-wrapper"><h2 id="using-built-in-commands">Using built-in commands</h2><a class="heading-link" href="#using-built-in-commands" aria-label="Link to 'Using built-in commands' section">#</a></div><p>The following is an example of using the build_runner <strong>build</strong> command:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ # From a directory that contains a pubspec.yaml file:</span></span> <span class="line"><span style="color:#222222">$ dart run build_runner build</span></span></code></pre></div></div><p>The build_runner package includes the following commands:</p><dl><dt>build</dt><dd>Performs a one-time build.</dd><dt>serve</dt><dd>Runs a development server. Instead of directly using this command, you can use <a href="/tools/webdev#serve"><code>webdev serve</code>,</a> which has convenient default behavior.</dd><dt>test</dt><dd>Runs <a href="/guides/testing">tests.</a></dd><dt>watch</dt><dd>Launches a build server that watches for edits to input files. Responds to changes by performing incremental rebuilds.</dd></dl><div class="header-wrapper"><h2 id="more-information">More information</h2><a class="heading-link" href="#more-information" aria-label="Link to 'More information' section">#</a></div><p>If you're working on web-specific code, see the <a href="/tools/webdev">webdev page.</a></p><p>For details on using build_runner, see the following:</p><ul><li>Documentation for packages that require you to use build_runner. These packages generally have a dependency <a href="https://pub.dev/packages?q=dependency%3Abuild">on build</a> or <a href="https://pub.dev/packages?q=dependency%3Abuild_runner">on build_runner.</a></li><li>Build_runner documentation:<ul><li><a href="https://github.com/dart-lang/build/blob/master/docs/getting_started.md">Getting started with build_runner</a></li><li><a href="https://github.com/dart-lang/build/blob/master/docs/faq.md">Build FAQ</a></li></ul></li></ul><p id="page-github-links"><span>Unless stated otherwise, the documentation on this site reflects Dart 3.5.4. Page last updated on 2024-09-16.</span> <a href="https://github.com/dart-lang/site-www/tree/main/src/content/tools/build_runner.md" target="_blank" rel="noopener">View source</a> <span>or </span><a href="https://github.com/dart-lang/site-www/issues/new?template=1_page_issue.yml&page-url=https://dart.dev/tools/build_runner/&page-source=https://github.com/dart-lang/site-www/tree/main/src/content/tools/build_runner.md" title="Report an issue with this page" target="_blank" rel="noopener">report an issue</a>.</p></div></article></main><footer id="page-footer"><div class="footer-section footer-main"><a href="/" class="brand" title="Dart"><img src="/assets/img/logo/logo-white-text.svg" alt="Dart" width="164"></a><div class="footer-social-links"><a href="https://medium.com/dartlang" target="_blank" rel="noopener" title="Medium blog"><svg><use href="/assets/img/social/medium.svg#medium"></use></svg> </a><a href="https://github.com/dart-lang" target="_blank" rel="noopener" title="GitHub"><svg><use href="/assets/img/social/github.svg#github"></use></svg> </a><a href="https://twitter.com/dart_lang" target="_blank" rel="noopener" title="X (Twitter)"><svg><use href="/assets/img/social/x.svg#x"></use></svg></a></div></div><div class="footer-section footer-tray"><div class="footer-licenses">Except as otherwise noted, this site is licensed under a <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>, and code samples are licensed under the <a href="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</a>.</div><div class="footer-utility-links"><ul><li><a href="/terms" title="Terms of use">Terms</a></li><li><a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy">Privacy</a></li><li><a href="/security" title="Security philosophy and practices">Security</a></li></ul></div></div></footer></body></html>