错误:未指定默认引擎且未提供扩展名

问题描述

我正在使用 node.js 和引擎设置 http 服务器.但是，我一直遇到一些关于如何解决的信息很少的问题，如果您能帮助解决这个问题，我将不胜感激.

I am working through setting up a http server using node.js and engine. However, I keep running into issues that I have little information on how to resolve I would appreciate some help solving this please.

Error: No default engine was specified and no extension was provided. 
at new View (...
ode_modulesexpresslibview.js:41:42) 
at Function.app.render (...
ode_modulesexpresslibapplication.js:484:12) 
at ServerResponse.res.render (...
ode_modulesexpresslib
esponse.js:783:7) 
at Layer.handle (...app.js:123:7) 
at trim_prefix (...
ode_modulesexpresslib
outerindex.js:225:17) 
at c (...
ode_modulesexpresslib
outerindex.js:198:9) 
at Function.proto.process_params (...
ode_modulesexpresslib
outerindex.js:253:12) 
at next (...
ode_modulesexpresslib
outerindex.js:189:19) 
at next (...
ode_modulesexpresslib
outerindex.js:202:7) 
at next (...
ode_modulesexpresslib
outerindex.js:166:38)

以下是我为启动此引擎而设置的内容.

Below is what I have set up to start up this engine.

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');
};

推荐答案

如果您不使用视图引擎，res.render 内容将引发错误.

The res.render stuff will throw an error if you're not using a view engine.

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

If you just want to serve json replace the res.render('error', { error: err }); lines in your code with:

res.json({ error: err })

PS:人们通常在返回的对象中也有消息:

PS: People usually also have message in the returned object:

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

这篇关于错误:未指定默认引擎且未提供扩展名的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！