这个Jade文件中的错误在哪里？

Question

Jade is not an easy language to deal with because of the proper indentation and what not, but in this case indentation does not seem to be the problem and I have Google-Foo'd the error and cannot find one that matches what is going on here.

This is my addpost.jade file:

extends layout

block content
    h1=title
    ul.errors
        if errors
            each error, i in errors
                li.alert.alert-danger #{error.msg}
    form(method='post', action='/posts/add', enctype="multipart/form-data")
        .form-group
            label Title:
            input.form-control(name='title', type='text')
        .form-group
            label Category
            select.form-control(name='category')
                each category, i in categories
                    option(value='#{category.title}') #{category.title}
        .form-group
            label Body
            textarea.form-control(name='body', id='body')
        .form-group
            label Main Image:
            input.form-control(name='mainimage', type='file')
        .form-group
            label Author
            select.form-control(name='author')
                option(value='Daniel Cortes') Daniel Cortes
                option(value='Alejandra Rocha') Alejandra Rocha
        input.btn.btn-default(name='submit', type='submit', value='Save')

And this is the error I am getting:

addpost.jade:16 14| label Category 15| select.form-control(name='category') > 16| each category, i in categories 17| option(value='#{category.title}') #{category.title} 18| .form-group 19| label Body Cannot read property 'length' of undefined

This is my posts.js file:

var express = require('express');
var router = express.Router();
var mongo = require('mongodb');
var db = require('monk')('localhost/nodeblog');

router.get('/add', function(req, res, next){
    var categories = db.get('categories');

    categories.find({},{},function(err, categories){
        res.render('addpost',{
        "title": "Add Post",
        "categories": categories
        });
    });


});

router.post('/add', function(req, res, next){
    // Get Form Values
    var title       = req.body.title;
    var category    = req.body.category;
    var body        = req.body.body;
    var author      = req.body.author;
    var date        = new Date();

    if(req.files.mainimage){
        var mainImageOriginalName   = req.files.mainimage.originalname;
        var mainImageName           = req.files.mainimage.name;
        var mainImageMime           = req.files.mainimage.mimetype;
        var mainImagePath           = req.files.mainimage.path;
        var mainImageExt            = req.files.mainimage.extension;
        var mainImageSize           = req.files.mainimage.size;
    } else {
        var mainImageName = 'noimage.png';
    }

    // Form Validation
    req.checkBody('title','Title field is required').notEmpty();
    req.checkBody('body', 'Body field is required');

    // Check errors
    var errors = req.validationErrors();

    if(errors){
        res.render('addpost',{
            "errors": errors,
            "title": title,
            "body": body
        });
    } else {
        var posts = db.get('posts');

        // Submit to db
        posts.insert({
            "title": title,
            "body": body,
            "category": category,
            "date": date,
            "author": author,
            "mainimage": mainimage
        }, function(err, post){
            if(err){
                res.send('There was an issue submitting the post');
            } else {
                req.flash('success','Post Submitted');
                res.location('/');
                res.redirect('/');
            }
        });
    }
});

module.exports = router;

my app.js file:

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var expressValidator = require('express-validator');
var cookieParser = require('cookie-parser');
var session = require('express-session');
var bodyParser = require('body-parser');
var mongo = require('mongodb');
var db = require('monk')('localhost/nodeblog');
var multer = require('multer');
var flash = require('connect-flash');

var routes = require('./routes/index');
var posts = require('./routes/posts');

var app = express();

app.locals.moment = require('moment');

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

// Handle File Uploads & Multipart Data
// app.use(multer({dest: './uploads'}));
app.use(multer({dest:'./uploads/'}).single('singleInputFileName'));

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());

// Express Session
app.use(session({
  secret: 'secret',
  saveUninitialized: true,
  resave: true
}));

// Express Validator
app.use(expressValidator({
  errorFormatter: function(param, msg, value){
    var namespace = param.split('.'),
    root = namespace.shift(),
    formParam = root;

    while(namespace.length) {
      formParam += '[' + namespace.shift() + ']';
    }
    return {
      param : formParam,
      msg   : msg,
      value : value
    };
  }
}));

app.use(express.static(path.join(__dirname, 'public')));

// Connect Flash
app.use(flash());
app.use(function (req, res, next) {
  res.locals.messages = require('express-messages')(req, res);
  next();
});

// Make our db accessible to our router
app.use(function(req, res, next){
  req.db = db;
  next();
});

app.use('/', routes);
app.use('/posts', posts);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// 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);
  res.render('error', {
    message: err.message,
    error: {}
  });
});


module.exports = app;

Answer 1

It seems that the categories is not passed to the view or its not a array.

Can you add the code that render the template? May be we can find the problem there.