ReferenceError：未定义“图片”。使用节点 JS答案

【问题标题】：ReferenceError: 'pictures' is not defined. Using Node JSReferenceError：未定义“图片”。使用节点 JS
【发布时间】：2016-01-19 10:03:13
【问题描述】：

到处搜索，但无法运行。我是新来的，所以我也很难搜索或修复正确的东西。尝试从数据库中获取数据，但未定义图片变量它说，我之前运行过，可能只是类型错误类似的东西，但我已经尝试了很多东西，而且我的学校项目已经没有时间了。这是我的代码：

index.ejs:

<main>
    <div class="jumbotron">
        <h1>Formula 1, see it, feel it!</h1></br>
        <p>Welkom! Op deze site vind u de meest mooie foto's van de Formule 1.</p>
    </div>
</main>

<div class="jumbotron">

       <% if(pictures.length){ %>     
<table>
    <tr>
        <th>Titel</th>
        <th>Locatie</th>
        <th>Datum</th>
        <th>Naam</th>
        <th>Waardering</th>

    </tr>
        <% } %>
        <% for (var i = 0; i < pictures.length; i++) { %>
    <tr>

        <td><%= pictures[i].titel %></td>
        <td><%= pictures[i].locatie %></td>
        <td><%= pictures[i].datum %></td>
        <td><%= pictures[i].naam %></td>
        <td><%= pictures[i].waardering %></td>
        <% } %>
    </tr>                   
</table>    

</div>

<footer>
    <% include ../partials/footer %>
</footer>

index.js

    var express = require('express');
var router = express.Router();

router.get('/', function(req, res) {
    req.getConnection(function(err, connection) {
        connection.query('SELECT * FROM pictures', function(err, results) {
            res.locals.pictures = results;
            console.log(results);
            res.render('../views/pages/index');
        });
    });
});

module.exports = router;

app.js：

var express = require('express'),
    path = require('path'),
    favicon = require('serve-favicon'),
    logger = require('morgan'),
    cookieParser = require('cookie-parser'),
    flash = require('connect-flash'),
    expressValidator = require('express-validator'),
    session = require('express-session'),
    passport = require('passport'),
    LocalStrategy = require('passport-local').Strategy,
    bodyParser = require('body-parser'),
    multer = require('multer'),
    mongo = require('mongodb'),
    mongoose = require('mongoose'),
    mysql = require('mysql'),
    myConnection = require('express-myconnection');

var db = mongoose.connection;

var dbOptions = {
    host: 'localhost',
    user: 'fcdeen_user',
    password: 'wEvGT9ctm8KUxdTD',
    database: 'fcdeen'
};

var indexRoutes = require('./routes/index'),    
    loginRoutes = require('./routes/login'),
    uploadRoutes = require('./routes/upload');

var app = express();

//Use session
app.use(session({
  secret: "Its_A_veRy_DarK_SecreT",
  resave: false,
  saveUninitialized: true
}));

// Voeg de bodyparser middleware aan de app toe (POST requests)
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));

// set the view engine to ejs
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

// Voeg connectie middleware toe aan app
app.use(myConnection(mysql, dbOptions, 'single'));

// index page 
app.get('/home', function(req, res) {
    res.render('pages/index');
});

// index page 
app.get('/index', function(req, res) {
    res.render('pages/index');
});

// upload page 
app.get('/upload', function(req, res) {
    res.render('pages/upload');
});

// login page 
app.get('/login', function(req, res) {
    res.render('pages/login');
});

app.listen(8080);
console.log('Launch at port 8080');

这是错误：

ReferenceError: C:\School\SSS 2015\testen\node-ejs-master\views\pages\index.ejs:21
   19| <div class="jumbotron">
   20|   
>> 21|   <% if(pictures.length){ %>     
   22| <table>
   23| <tr>
   24| <th>Titel</th>

pictures is not defined
   at eval (eval at <anonymous> (C:\School\SSS 2015\testen\node-ejs-master\node_modules\ejs\lib\ejs.js:242:14), <anonymous>:33:292)
   at eval (eval at <anonymous> (C:\School\SSS 2015\testen\node-ejs-master\node_modules\ejs\lib\ejs.js:242:14), <anonymous>:35:68)
   at C:\School\SSS 2015\testen\node-ejs-master\node_modules\ejs\lib\ejs.js:255:15
   at Object.exports.render (C:\School\SSS 2015\testen\node-ejs-master\node_modules\ejs\lib\ejs.js:293:13)
   at View.exports.renderFile [as engine] (C:\School\SSS 2015\testen\node-ejs-master\node_modules\ejs\lib\ejs.js:323:20)
   at View.render (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\view.js:126:8)
   at tryRender (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\application.js:639:10)
   at EventEmitter.render (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\application.js:591:3)
   at ServerResponse.render (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\response.js:961:7)
   at C:\School\SSS 2015\testen\node-ejs-master\app.js:61:6
   at Layer.handle [as handle_request] (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\layer.js:95:5)
   at next (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\route.js:131:13)
   at Route.dispatch (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\route.js:112:3)
   at Layer.handle [as handle_request] (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\layer.js:95:5)
   at C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:277:22
   at Function.process_params (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:330:12)
   at next (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:271:10)
   at C:\School\SSS 2015\testen\node-ejs-master\node_modules\express-myconnection\lib\express-myconnection.js:123:9
   at Layer.handle [as handle_request] (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\layer.js:95:5)
   at trim_prefix (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:312:13)
   at C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:280:7
   at Function.process_params (C:\School\SSS 2015\testen\node-ejs-master\node_modules\express\lib\router\index.js:330:12)

感谢您的帮助！

【问题讨论】：

你使用的是mysql数据库吗？你能指定你正在使用的数据库和驱动程序吗？
是的，我正在使用 phpmyadmin，不知道你的驱动是什么意思？
不用担心驱动，我已经看到你正在使用mysql 模块。您能否向我们展示console.log(results); 的输出。但是请这样修改console.log("Results: ", results.length);
看不到输出，因为它仍然给出该错误。它只显示错误日志
这是不可能的。您在渲染视图之前显示结果。所以你必须在跟踪错误生成渲染视图之前看到一些东西。如果您更改我告诉您的代码行，您应该会在堆栈跟踪之后看到类似 Results: 的内容。

标签： javascript node.js referenceerror

【解决方案1】：

我认为这是您问题的解决方案

// Don't separate the routes. If you are setting your routes in this file, try keep every route at the same file.

app.get('/', function(req, res) {
    req.getConnection(function(err, connection) {
        connection.query('SELECT * FROM pictures', function(err, results) {
            res.locals.pictures = results;
            console.log(results);
            res.render('pages/index', {pictures : results});
        });
    });
});

// index page 
app.get('/home', function(req, res) {
    res.render('pages/index');
});

// index page 
app.get('/index', function(req, res) {
    res.render('pages/index');
});

当您输入/home 或/index 时，您必须看到错误，但/ 应该没有问题。

如果您尝试让这三个路由执行相同的操作，您可以试试这个：

app.get('/', renderPageIndex)

// index page 
app.get('/home', renderPageIndex)

// index page 
app.get('/index', renderPageIndex )

function renderPageIndexfunction(req, res) {
    req.getConnection(function(err, connection) {
        connection.query('SELECT * FROM pictures', function(err, results) {
            res.locals.pictures = results;
            console.log(results);
            res.render('pages/index', {pictures : results});
        });
    });
});

【讨论】：

确实成功了 :) 非常感谢！只需要弄清楚导航栏是如何正常工作的。现在，当我按下主菜单时，它再次出现错误。
查看更新的答案，这可以解决其他错误

【解决方案2】：

你应该把图片传入渲染函数

 return res.render('../views/pages/index', {pictures : results} );

【讨论】：