/// <summary>
/// Starts the webpack dev server. If the start fails for known reason, modifies the aspnet-webpack module to be compliant with webpack-dev-middleware 5.
/// For compatibility purposes as the change is rather samll it's easier to modify the existing module than to create new NPM package and enforce anyone to udpate.
/// </summary>
private static WebpackDevServerInfo StartWebpackDevServer(IDictionary <string, string> environmentVariables, string projectPath, WebpackDevServerArgs devServerArgs, bool fixAttempted)
{
// Unlike other consumers of NodeServices, WebpackDevMiddleware dosen't share Node instances, nor does it
// use your DI configuration. It's important for WebpackDevMiddleware to have its own private Node instance
// because it must *not* restart when files change (if it did, you'd lose all the benefits of Webpack
// middleware). And since this is a dev-time-only feature, it doesn't matter if the default transport isn't
// as fast as some theoretical future alternative.
// This should do it by using Jering.Javascript.NodeJS interop
var nodeJSService = NodeInteropFactory.BuildNewInstance(environmentVariables, projectPath);
try
{
return(nodeJSService.InvokeFromStringAsync <WebpackDevServerInfo>(
EmbeddedResourceReader.Read(typeof(WebpackDevMiddleware), "/Content/Node/webpack-dev-middleware.js"), //Embedded JS file
args: new object[] { JsonSerializer.Serialize(devServerArgs, jsonSerializerOptions) } //Options patched so that they work with aspnet-webpack package
).Result);
}
catch (Exception ex)
{
if (fixAttempted)
{
throw;
}
if (ex != null && ex.Message.Contains("Dev Middleware has been initialized using an options object that does not match the API schema."))
{
//Attempt to modify module file so that it doesn't contain arguments not recognized by the webpack-dev-middleware 5
try
{
const string SEARCH_PATTERN = "at validate (";
var startIndex = ex.Message.IndexOf(SEARCH_PATTERN);
if (startIndex > -1)
{
startIndex += SEARCH_PATTERN.Length;
var endIndex = ex.Message.IndexOf("webpack-dev-middleware", startIndex);
var modulesPath = ex.Message.Substring(startIndex, endIndex - startIndex);
if (Directory.Exists(modulesPath))
{
var modulePath = Path.Combine(modulesPath, @"aspnet-webpack\WebpackDevMiddleware.js");
if (File.Exists(modulePath))
{
var fileContent = File.ReadAllText(modulePath);
fileContent = fileContent.Replace("noInfo: true,", "");
fileContent = fileContent.Replace("watchOptions: webpackConfig.watchOptions", "");
File.WriteAllText(modulePath, fileContent);
nodeJSService.Dispose();
return(StartWebpackDevServer(environmentVariables, projectPath, devServerArgs, true));
}
}
}
}
catch (Exception)
{ }
}
throw;
}
}
/// <summary>
/// Creates a new instance of <see cref="PrerenderTagHelper"/>.
/// </summary>
/// <param name="serviceProvider">The <see cref="IServiceProvider"/>.</param>
public PrerenderTagHelper(IServiceProvider serviceProvider)
{
var hostEnv = (IWebHostEnvironment)serviceProvider.GetService(typeof(IWebHostEnvironment));
_nodeServices = NodeInteropFactory.GetInstance(serviceProvider) ?? _fallbackNodeServices;
_applicationBasePath = hostEnv.ContentRootPath;
var applicationLifetime = (IHostApplicationLifetime)serviceProvider.GetService(typeof(IHostApplicationLifetime));
_applicationStoppingToken = applicationLifetime.ApplicationStopping;
// Consider removing the following. Having it means you can get away with not putting app.AddNodeServices()
// in your startup file, but then again it might be confusing that you don't need to.
if (_nodeServices == null)
{
_nodeServices = _fallbackNodeServices = NodeInteropFactory.BuildNewInstance(serviceProvider);
}
}
