错误:未指定默认引擎且未提供扩展名


132

我正在通过使用node.js和引擎设置http服务器的工作。但是,我遇到的问题是我几乎没有解决方法的信息,请帮忙解决此问题。

Error: No default engine was specified and no extension was provided. 
at new View (...\node_modules\express\lib\view.js:41:42) 
at Function.app.render (...\node_modules\express\lib\application.js:484:12) 
at ServerResponse.res.render (...\node_modules\express\lib\response.js:783:7) 
at Layer.handle (...\app.js:123:7) 
at trim_prefix (...\node_modules\express\lib\router\index.js:225:17) 
at c (...\node_modules\express\lib\router\index.js:198:9) 
at Function.proto.process_params (...\node_modules\express\lib\router\index.js:253:12) 
at next (...\node_modules\express\lib\router\index.js:189:19) 
at next (...\node_modules\express\lib\router\index.js:202:7) 
at next (...\node_modules\express\lib\router\index.js:166:38)

以下是我为启动此引擎而设置的内容。

var http = require('http');  
var module = require("module")
var logger = require('morgan');
var express = require('express');
var app =  module.exports = express();
var silent = 'test' == process.env.NODE_ENV;
var httpServer = http.createServer(app);  // app middleware

app.enable('strict routing');
// app.all('*', function(req, res, next)/*** CORS support.*/
// {
//   if (!req.get('Origin')) return next();// use "*" here to accept any origin
//   res.set('Access-Control-Allow-Origin', 'http://localhost:3000');
//   res.set('Access-Control-Allow-Methods', 'GET, POST');
//   res.set('Access-Control-Allow-Headers', 'X-Requested-With, Content-Type');
//   res.set('Access-Control-Allow-Max-Age', 3600);
//   if ('OPTIONS' == req.method) return res.send(200);
//   next();
// });
app.set('views', __dirname + '/views'); // general config
app.set('view engine', 'html');
app.get('/404', function(req, res, next){
next();// trigger a 404 since no other middleware will match /404 after this one, and we're not responding here
});
app.get('/403', function(req, res, next){// trigger a 403 error
  var err = new Error('not allowed!');
  err.status = 403;
  next(err);
});
app.get('/500', function(req, res, next){// trigger a generic (500) error
  next(new Error('keyboard cat!'));
});
app.use(express.static(__dirname + '/public')); 
//error handlers
app.use(logErrors);
app.use(clientErrorHandler);
app.use(errorHandler);  
// middleware with an arity of 4 are considered error handling middleware. When you next(err)
// it will be passed through the defined middleware in order, but ONLY those with an arity of 4, ignoring regular middleware.
function clientErrorHandler(err, req, res, next) {
  if (req.xhr) {// whatever you want here, feel free to populate properties on `err` to treat it differently in here.
  res.send(err.status || 500, { error: err.message });
  } 
  else 
  { next(err);}
};
// create an error with .status. we can then use the property in our custom error handler (Connect repects this prop as well)
function error  (status, msg) {
  var err = new Error(msg);
  err.status = status;
  return err;
};
function logErrors  (err, req, res, next) {
  console.error(err.stack);
  next(err);
};
function errorHandler (err, req, res, next) {
  res.status(500);
  res.render('error', { error: err });
};

// Error handlers
// Since this is the last non-error-handling middleware use()d, we assume 404, as nothing else responded.
// $ curl http://localhost:3000/notfound
// $ curl http://localhost:3000/notfound -H "Accept: application/json"
// $ curl http://localhost:3000/notfound -H "Accept: text/plain"
app.use(function(req, res, next){
  res.status(404); 
  if (req.accepts('html')) {// respond with html page
    res.render('404', { url: req.url });
    return;
  } 
  if (req.accepts('json')) {// respond with json
    res.send({ error: 'Not found' });
    return;
  } 
  res.type('txt').send('Not found');// default to plain-text. send()
});

// error-handling middleware, take the same form as regular middleware, however they require an
// arity of 4, aka the signature (err, req, res, next).when connect has an error, it will invoke ONLY error-handling middleware.

// If we were to next() here any remaining non-error-handling middleware would then be executed, or if we next(err) to
// continue passing the error, only error-handling middleware would remain being executed, however here
// we simply respond with an error page.
app.use(function(err, req, res, next){
  // we may use properties of the error object here and next(err) appropriately, or if we possibly recovered from the error, simply next().
  res.status(err.status || 500);
  res.render('500', { error: err });
});

if (!module.parent) {// assigning to exports will not modify module, must use module.exports
  app.listen(3000);
  silent || console.log('Express started on port 3000');
};

Answers:


120

如果您不使用视图引擎,则res.render内容将引发错误。

如果您只想提供json res.render('error', { error: err });,请将代码中的行替换为:

res.json({ error: err })

PS:人们通常在返回的对象中也有消息:

res.status(err.status || 500);
res.json({
  message: err.message,
  error: err
});

102

您缺少视图引擎,例如使用jade

改变你的

app.set('view engine', 'html');

app.set('view engine', 'jade');

如果要使用html友好语法,请改用ejs

app.engine('html', require('ejs').renderFile);
app.set('view engine', 'html');

编辑

正如您可以从view.js Express View Module中读取的内容

module.exports = View;

/**
 * Initialize a new `View` with the given `name`.
 *
 * Options:
 *
 *   - `defaultEngine` the default template engine name
 *   - `engines` template engine require() cache
 *   - `root` root path for view lookup
 *
 * @param {String} name
 * @param {Object} options
 * @api private
 */

function View(name, options) {
  options = options || {};
  this.name = name;
  this.root = options.root;
  var engines = options.engines;
  this.defaultEngine = options.defaultEngine;
  var ext = this.ext = extname(name);
  if (!ext && !this.defaultEngine) throw new Error('No default engine was specified and no extension was provided.');
  if (!ext) name += (ext = this.ext = ('.' != this.defaultEngine[0] ? '.' : '') + this.defaultEngine);
  this.engine = engines[ext] || (engines[ext] = require(ext.slice(1)).__express);
  this.path = this.lookup(name);
}

您必须已安装 default engine

Express通过program.template以下内容搜索默认布局视图:

mkdir(path + '/views', function(){
      switch (program.template) {
        case 'ejs':
          write(path + '/views/index.ejs', ejsIndex);
          break;
        case 'jade':
          write(path + '/views/layout.jade', jadeLayout);
          write(path + '/views/index.jade', jadeIndex);
          break;
        case 'jshtml':
          write(path + '/views/layout.jshtml', jshtmlLayout);
          write(path + '/views/index.jshtml', jshtmlIndex);
          break;
        case 'hjs':
          write(path + '/views/index.hjs', hoganIndex);
          break;

      }
    });

正如您在下面看到的:

program.template = 'jade';
if (program.ejs) program.template = 'ejs';
if (program.jshtml) program.template = 'jshtml';
if (program.hogan) program.template = 'hjs';

默认的视图引擎是 jade


2
嗨,您能否进一步说明这是如何工作的?我开始阅读node.js时,以为这是我所需要的,但是当我仍然无法显示我的页面时,我查了查原因并着眼于快速信息。现在,我在快速4.2页面上关注了信息,并遇到了您可以帮助解决的错误。现在我得到了ejs,但它似乎仍然不是我所需要的。能否请您告诉我这应该如何工作?
Kobojunkie 2014年


我曾想过阅读,即使您正在注释视图,也必须明确定义视图引擎。事实并非如此。
stevejpurves 2015年

15

注释掉res.render代码中的行,然后添加next(err);。如果您不使用视图引擎,则res.render这些东西将引发错误。

抱歉,您还必须注释掉这一行:

app.set('view engine', 'html');

我的解决方案将导致虽然不使用视图引擎。您不需要视图引擎,但是如果这是目标,请尝试以下操作:

app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
//swap jade for ejs etc

res.render使用视图引擎时,也将需要这些行。像这样:

// error handlers
// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
  app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
    message: err.message,
    error: err
    });
  });
}
// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  next(err);
  res.render('error', {
  message: err.message,
  error: {}
  });
});

12

如果您希望呈现html文件,请使用:

response.sendfile('index.html');

然后删除:

app.set('view engine', 'html');

把你*.htmlviews目录,或成为一个public目录作为静态的目录,并把index.htmlpublic目录。


4
response.sendfile()不推荐使用,response.sendFile()而是使用。注意大写字母“ F”。
Pramesh Bajracharya

6

设置视图引擎以下方式

app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

4

如果只需在代码中内联发送html代码,我们可以在下面使用

var app = express();
app.get('/test.html', function (req, res) {
   res.header('Content-Type', 'text/html').send("<html>my html code</html>");
});

0

我刚收到此错误消息,问题是我没有正确设置中间件。

我正在MEAN堆栈中构建博客,并且需要对在前端使用的.jade文件进行正文解析。这是我的项目中“ /middleware/index.js ”文件中的代码片段。

var express = require('express');
var morgan = require('morgan');
var session = require('express-session');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

module.exports = function (app) {
app.use(morgan('dev'));

// Good for now
// In the future, use connect-mongo or similar
// for persistant sessions
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: true
}));
app.use(cookieParser());
app.use(session({secret: 'building a blog', saveUninitialized: true, resave: true}));

另外,这是我的“ package.json ”文件,您可能正在使用不同版本的技术。注意:由于不确定它们之间的依赖关系,因此将整个文件包含在此处:

"dependencies": {
    "body-parser": "1.12.3",
    "consolidate": "0.12.1",
    "cookie-parser": "1.3.4",
    "crypto": "0.0.3",
    "debug": "2.1.1",
    "express": "4.12.2",
    "express-mongoose": "0.1.0",
    "express-session": "1.11.1",
    "jade": "1.9.2",
    "method-override": "2.3.2",
    "mongodb": "2.0.28",
    "mongoose": "4.0.2",
    "morgan": "1.5.1",
    "request": "2.55.0",
    "serve-favicon": "2.2.0",
    "swig": "1.4.2"
  }

希望这对某人有帮助!祝一切顺利!


0

上面的答案是正确的,但是我发现一个简单的错字也会产生此错误。例如,我使用var router = express()而不是var router = express.Router()并收到此错误。因此应为以下内容:

// App.js 
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
app.use(bodyParser.urlencoded({ extended:false}));
// assuming you put views folder in the same directory as app.js
app.set('views', __dirname + '/views')
app.engine('ejs', ejs.renderFile);
app.set('view engine', 'ejs');
// router - wherever you put it, could be in app.js
var router = express.Router();
router.get('/', function (req,res) {
  res.render('/index.ejs');
})

0

您可以使用express-error-handler将静态html页面用于错误处理并避免定义视图处理程序。

该错误可能是由404引起的,也许是缺少图标(如果包含了先前的控制台消息,则为明显)。“ html”的“视图处理程序”在4.x express中似乎无效。

无论原因如何,只要您修改配置的其他元素,就可以避免定义(有效)视图处理程序。

您要解决此问题的选项是:

  • 与其他答案一样定义一个有效的视图处理程序
  • 使用send()而不是render直接返回内容

http://expressjs.com/en/api.html#res.render

使用不带文件路径的渲染会自动调用视图处理程序,就像配置中的以下两行一样:

res.render('404', { url: req.url });

和:

res.render('500);

确保使用以下命令安装express-error-handler:

npm install --save express-error-handler

然后将其导入到您的app.js中

var ErrorHandler = require('express-error-handler');

然后将错误处理更改为使用:

// define below all other routes
var errorHandler = ErrorHandler({
  static: {
    '404': 'error.html' // put this file in your Public folder
    '500': 'error.html' // ditto
});

// any unresolved requests will 404
app.use(function(req,res,next) {
  var err = new Error('Not Found');
  err.status(404);
  next(err);
}

app.use(errorHandler);


0

错误:未指定默认引擎且未提供扩展名

我遇到了同样的问题(用于执行平均堆栈项目)。问题是我没有提到要安装npm的方法,例如;pug或jade,ejs等,因此要解决此问题,请输入express --view = pug文件夹名称。这将在给定的文件夹中加载必要的pug文件(index.pug,layout.pug等。)。


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