mirror of
https://github.com/aspnet/JavaScriptServices.git
synced 2025-12-25 11:07:29 +00:00
Reduce SpaServices's built-in JS to simply invoke exports from the corresponding new NPM packages
This commit is contained in:
SteveSandersonMS
@@ -1,188 +1,12 @@
|
||||
// -----------------------------------------------------------------------------------------
|
||||
// Loading via Webpack
|
||||
// This is optional. You don't have to use Webpack. But if you are doing, it's extremely convenient
|
||||
// to be able to load your boot module via Webpack compilation, so you can use whatever source language
|
||||
// you like (e.g., TypeScript), and so that loader plugins (e.g., require('./mystyles.less')) work in
|
||||
// exactly the same way on the server as you do on the client.
|
||||
// If you don't use Webpack, then it's up to you to define a plain-JS boot module that in turn loads
|
||||
// whatever other files you need (e.g., using some other compiler/bundler API, or maybe just having
|
||||
// already precompiled to plain JS files on disk).
|
||||
function loadViaWebpackNoCache(webpackConfigPath, modulePath) {
|
||||
var ExternalsPlugin = require('webpack-externals-plugin');
|
||||
var requireFromString = require('require-from-string');
|
||||
var MemoryFS = require('memory-fs');
|
||||
var webpack = require('webpack');
|
||||
|
||||
return new Promise(function(resolve, reject) {
|
||||
// Load the Webpack config and make alterations needed for loading the output into Node
|
||||
var webpackConfig = require(webpackConfigPath);
|
||||
webpackConfig.entry = modulePath;
|
||||
webpackConfig.target = 'node';
|
||||
webpackConfig.output = { path: '/', filename: 'webpack-output.js', libraryTarget: 'commonjs' };
|
||||
|
||||
// In Node, we want anything under /node_modules/ to be loaded natively and not bundled into the output
|
||||
// (partly because it's faster, but also because otherwise there'd be different instances of modules
|
||||
// depending on how they were loaded, which could lead to errors)
|
||||
webpackConfig.plugins = webpackConfig.plugins || [];
|
||||
webpackConfig.plugins.push(new ExternalsPlugin({ type: 'commonjs', include: /node_modules/ }));
|
||||
|
||||
// The CommonsChunkPlugin is not compatible with a CommonJS environment like Node, nor is it needed in that case
|
||||
webpackConfig.plugins = webpackConfig.plugins.filter(function(plugin) {
|
||||
return !(plugin instanceof webpack.optimize.CommonsChunkPlugin);
|
||||
});
|
||||
|
||||
// The typical use case for DllReferencePlugin is for referencing vendor modules. In a Node
|
||||
// environment, it doesn't make sense to load them from a DLL bundle, nor would that even
|
||||
// work, because then you'd get different module instances depending on whether a module
|
||||
// was referenced via a normal CommonJS 'require' or via Webpack. So just remove any
|
||||
// DllReferencePlugin from the config.
|
||||
// If someone wanted to load their own DLL modules (not an NPM module) via DllReferencePlugin,
|
||||
// that scenario is not supported today. We would have to add some extra option to the
|
||||
// asp-prerender tag helper to let you specify a list of DLL bundles that should be evaluated
|
||||
// in this context. But even then you'd need special DLL builds for the Node environment so that
|
||||
// external dependencies were fetched via CommonJS requires, so it's unclear how that could work.
|
||||
// The ultimate escape hatch here is just prebuilding your code as part of the application build
|
||||
// and *not* using asp-prerender-webpack-config at all, then you can do anything you want.
|
||||
webpackConfig.plugins = webpackConfig.plugins.filter(function(plugin) {
|
||||
return !(plugin instanceof webpack.DllReferencePlugin);
|
||||
});
|
||||
|
||||
// Create a compiler instance that stores its output in memory, then load its output
|
||||
var compiler = webpack(webpackConfig);
|
||||
compiler.outputFileSystem = new MemoryFS();
|
||||
compiler.run(function(err, stats) {
|
||||
if (err) {
|
||||
reject(err);
|
||||
} else {
|
||||
var fileContent = compiler.outputFileSystem.readFileSync('/webpack-output.js', 'utf8');
|
||||
var moduleInstance = requireFromString(fileContent);
|
||||
resolve(moduleInstance);
|
||||
}
|
||||
});
|
||||
});
|
||||
}
|
||||
|
||||
// Ensure we only go through the compile process once per [config, module] pair
|
||||
var loadViaWebpackPromisesCache = {};
|
||||
function loadViaWebpack(webpackConfigPath, modulePath, callback) {
|
||||
var cacheKey = JSON.stringify(webpackConfigPath) + JSON.stringify(modulePath);
|
||||
if (!(cacheKey in loadViaWebpackPromisesCache)) {
|
||||
loadViaWebpackPromisesCache[cacheKey] = loadViaWebpackNoCache(webpackConfigPath, modulePath);
|
||||
// Pass through the invocation to the 'aspnet-prerendering' package, verifying that it can be loaded
|
||||
module.exports.renderToString = function (callback) {
|
||||
var aspNetPrerendering;
|
||||
try {
|
||||
aspNetPrerendering = require('aspnet-prerendering');
|
||||
} catch (ex) {
|
||||
callback('To use prerendering, you must install the \'aspnet-prerendering\' NPM package.');
|
||||
return;
|
||||
}
|
||||
loadViaWebpackPromisesCache[cacheKey].then(function(result) {
|
||||
callback(null, result);
|
||||
}, function(error) {
|
||||
callback(error);
|
||||
})
|
||||
}
|
||||
|
||||
// -----------------------------------------------------------------------------------------
|
||||
// Rendering
|
||||
|
||||
var url = require('url');
|
||||
var path = require('path');
|
||||
var domain = require('domain');
|
||||
var domainTask = require('domain-task');
|
||||
var baseUrl = require('domain-task/fetch').baseUrl;
|
||||
|
||||
function findBootModule(applicationBasePath, bootModule, callback) {
|
||||
var bootModuleNameFullPath = path.resolve(applicationBasePath, bootModule.moduleName);
|
||||
if (bootModule.webpackConfig) {
|
||||
var webpackConfigFullPath = path.resolve(applicationBasePath, bootModule.webpackConfig);
|
||||
loadViaWebpack(webpackConfigFullPath, bootModuleNameFullPath, callback);
|
||||
} else {
|
||||
callback(null, require(bootModuleNameFullPath));
|
||||
}
|
||||
}
|
||||
|
||||
function findBootFunc(applicationBasePath, bootModule, callback) {
|
||||
// First try to load the module (possibly via Webpack)
|
||||
findBootModule(applicationBasePath, bootModule, function(findBootModuleError, foundBootModule) {
|
||||
if (findBootModuleError) {
|
||||
callback(findBootModuleError);
|
||||
return;
|
||||
}
|
||||
|
||||
// Now try to pick out the function they want us to invoke
|
||||
var bootFunc;
|
||||
if (bootModule.exportName) {
|
||||
// Explicitly-named export
|
||||
bootFunc = foundBootModule[bootModule.exportName];
|
||||
} else if (typeof foundBootModule !== 'function') {
|
||||
// TypeScript-style default export
|
||||
bootFunc = foundBootModule.default;
|
||||
} else {
|
||||
// Native default export
|
||||
bootFunc = foundBootModule;
|
||||
}
|
||||
|
||||
// Validate the result
|
||||
if (typeof bootFunc !== 'function') {
|
||||
if (bootModule.exportName) {
|
||||
callback(new Error('The module at ' + bootModule.moduleName + ' has no function export named ' + bootModule.exportName + '.'));
|
||||
} else {
|
||||
callback(new Error('The module at ' + bootModule.moduleName + ' does not export a default function, and you have not specified which export to invoke.'));
|
||||
}
|
||||
} else {
|
||||
callback(null, bootFunc);
|
||||
}
|
||||
});
|
||||
}
|
||||
|
||||
function renderToString(callback, applicationBasePath, bootModule, absoluteRequestUrl, requestPathAndQuery) {
|
||||
findBootFunc(applicationBasePath, bootModule, function (findBootFuncError, bootFunc) {
|
||||
if (findBootFuncError) {
|
||||
callback(findBootFuncError);
|
||||
return;
|
||||
}
|
||||
|
||||
// Prepare a promise that will represent the completion of all domain tasks in this execution context.
|
||||
// The boot code will wait for this before performing its final render.
|
||||
var domainTaskCompletionPromiseResolve;
|
||||
var domainTaskCompletionPromise = new Promise(function (resolve, reject) {
|
||||
domainTaskCompletionPromiseResolve = resolve;
|
||||
});
|
||||
var params = {
|
||||
location: url.parse(requestPathAndQuery),
|
||||
url: requestPathAndQuery,
|
||||
absoluteUrl: absoluteRequestUrl,
|
||||
domainTasks: domainTaskCompletionPromise
|
||||
};
|
||||
|
||||
// Open a new domain that can track all the async tasks involved in the app's execution
|
||||
domainTask.run(function() {
|
||||
// Workaround for Node bug where native Promise continuations lose their domain context
|
||||
// (https://github.com/nodejs/node-v0.x-archive/issues/8648)
|
||||
bindPromiseContinuationsToDomain(domainTaskCompletionPromise, domain.active);
|
||||
|
||||
// Make the base URL available to the 'domain-tasks/fetch' helper within this execution context
|
||||
baseUrl(absoluteRequestUrl);
|
||||
|
||||
// Actually perform the rendering
|
||||
bootFunc(params).then(function(successResult) {
|
||||
callback(null, { html: successResult.html, globals: successResult.globals });
|
||||
}, function(error) {
|
||||
callback(error, null);
|
||||
});
|
||||
}, function allDomainTasksCompleted(error) {
|
||||
// There are no more ongoing domain tasks (typically data access operations), so we can resolve
|
||||
// the domain tasks promise which notifies the boot code that it can do its final render.
|
||||
if (error) {
|
||||
callback(error, null);
|
||||
} else {
|
||||
domainTaskCompletionPromiseResolve();
|
||||
}
|
||||
});
|
||||
});
|
||||
}
|
||||
|
||||
function bindPromiseContinuationsToDomain(promise, domainInstance) {
|
||||
var originalThen = promise.then;
|
||||
promise.then = function then(resolve, reject) {
|
||||
if (typeof resolve === 'function') { resolve = domainInstance.bind(resolve); }
|
||||
if (typeof reject === 'function') { reject = domainInstance.bind(reject); }
|
||||
return originalThen.call(this, resolve, reject);
|
||||
};
|
||||
}
|
||||
|
||||
module.exports.renderToString = renderToString;
|
||||
|
||||
return aspNetPrerendering.renderToString.apply(this, arguments);
|
||||
};
|
||||
|
||||
Reference in New Issue
Block a user