注意：虽然本文只会介绍 Mongo 以及 Mongoose 类库的使用。
但是如果你和我一样对 SQL 非常熟悉并且希望在 Express 使用关系数据库的话，你可以去查看 Sequelize。它为很多关系型数据库提供了良好的支持。

\x16\x00\x00\x00\x02hello\x00\x06\x00\x00\x00world\x00\x00

var mongoose = require("mongoose");
var userSchema = mongoose.Schema({
    username: { type: String, require: true, unique: true },
    password: { type: String, require: true },
    createdAt: {type: Date, default: Date.now },
    displayName: String,
    bio: String
});

...

userSchema.methods.name = function() {
    return this.displayName || this.username;
}

var bcrypt = require("bcrypt-nodejs");
var SALT_FACTOR = 10;

...

var noop = function() {};
// 保存操作之前的回调函数
userSchema.pre("save", function(done) {
    var user = this;
    if (!user.isModified("password")) {
        return done();
    }

    bcrypt.genSalt(SALT_FACTOR, function(err, salt) {
        if (err) { 
            return done(err); 
        }

        bcrypt.hash(user.password, salt, noop, 
            function(err, hashedPassword) {
                if (err) {
                    return done(err); 
                }
                user.password = hashedPassword;
                done();
            }
        );
    });
});

...

userSchema.methods.checkPassword = function(guess, done) {
    bcrypt.compare(guess, this.password, function(err, isMatch) {
        done(err, isMatch);
    });
}

...

var User = mongoose.model("User", userSchema);
module.exports = User;

// 代码清单 8.8 models/user.js编写完成之后
var bcrypt = require("bcrypt-nodejs");
var SALT_FACTOR = 10;
var mongoose = require("mongoose");
var userSchema = mongose.Schema({
    username: { type: String, require: true, unique: true },
    password: { type: String, require: true },
    createdAt: {type: Date, default: Date.now },
    displayName: String,
    bio: String
});
userSchema.methods.name = function() {
    return this.displayName || this.username;
}

var noop = function() {};

userSchema.pre("save", function(done) {
    var user = this;
    if (!user.isModified("password")) {
        return done();
    }

    bcrypt.genSalt(SALT_FACTOR, function(err, salt) {
        if (err) { return done(err); }
        bcrypt.hash(user.password, salt, noop, 
            function(err, hashedPassword) {
                if (err) { return done(err); }
                user.password = hashedPassword;
                done();
            }
        );
    });
});
userSchema.methods.checkPassword = function(guess, done) {
    bcrypt.compare(guess, this.password, function(err, isMatch) {
        done(err, isMatch);
    });
}
var User = mongoose.model("User", userSchema);
module.exports = User;

var express = require("express");
var mongoose = require("mongoose");
var path = require("path");
var bodyParser = require("body-parser");
var cookieParser = require("cookie-parser");
var session = require("express-session");
var flash = require("connect-flash");

var routes = require("./routes");
var app = express();

// 连接到你MongoDB服务器的test数据库
mongoose.connect("mongodb://localhost:27017/test");
app.set("port", process.env.PORT || 3000);
app.set("views", path.join(__dirname, "views"));
app.set("view engine", "ejs");

app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(session({
    secret: "TKRv0IJs=HYqrvagQ#&!F!%V]Ww/4KiVs$s,<<MX",
    resave: true,
    saveUninitialized: true
}));
app.use(flash());
app.use(routes);

app.listen(app.get("port"), function() {
    console.log("Server started on port " + app.get("port"));
});

var express = require("express");
var User = require("./models/user");
var router = express.Router();
router.use(function(req, res, next) {
    res.locals.currentUser = req.user;
    res.locals.errors = req.flash("error");
    res.locals.infos = req.flash("info");
    next();
});
router.get("/", function(req, res, next) {
    User.find()
        .sort({ createdAt: "descending" })
        .exec(function(err, users) {
            if (err) { return next(err); }
            res.render("index", { users: users });
        });
});
module.exports = router;

</div>
</body>
</html>

<% include _header %>
<h1>Welcome to Learn About Me!</h1>
<% users.forEach(function(user) { %>
    <div class="panel panel-default">
        <div class="panel-heading">
            <a href="/users/<%= user.username %>">
                <%= user.name() %>
            </a>
        </div>
        <% if (user.bio) { %>
            <div class="panel-body"><%= user.bio %></div>
        <% } %>
    </div>
<% }) %>
<% include _footer %>

var bodyParser = require("body-parser");
...

app.use(bodyParser.urlencoded({ extended: false }));
…

var passport = require("passport");
...
router.get("/signup", function(req, res) {
    res.render("signup");
});
router.post("/signup", function(req, res, next) {
    // 参数解析
    var username = req.body.username;
    var password = req.body.password;

    // 调用findOne只返回一个用户。你想在这匹配一个用户名
    User.findOne({ username: username }, function(err, user) {
        if (err) { return next(err); }
        // 判断用户是否存在
        if (user) {
            req.flash("error", "User already exists");
            return res.redirect("/signup");
        }
        // 新建用户
        var newUser = new User({
            username: username,
            password: password
        });
        // 插入记录
        newUser.save(next);
    });
    // 进行登录操作并实现重定向
}, passport.authenticate("login", {
    successRedirect: "/",
    failureRedirect: "/signup",
    failureFlash: true
}));

// 拷贝代码到 views/signup.ejs
<% include _header %>
<h1>Sign up</h1>
<form action="/signup" method="post">
    <input name="username" type="text" class="form-control" placeholder="Username" required autofocus>
    <input name="password" type="password" class="form-control" placeholder="Password" required>
    <input type="submit" value="Sign up" class="btn btn-primary btn-block">
</form>
<% include _footer %>

...
router.get("/users/:username", function(req, res, next) {
    User.findOne({ username: req.params.username }, function(err, user) {
        if (err) { return next(err); }
        if (!user) { return next(404); }
        res.render("profile", { user: user });
    });
});
...

// 保存到 views 文件夹中
<% include _header %>
<!-- 
    参考变量currentUser来判断你的登陆状态。不过现在它总会是false状态
 -->
<% if ((currentUser) && (currentUser.id === user.id)) { %>
    <a href="/edit" class="pull-right">Edit your profile</a>
<% } %>
<h1><%= user.name() %></h1>
<h2>Joined on <%= user.createdAt %></h2>
<% if (user.bio) { %>
    <p><%= user.bio %></p>
<% } %>
<% include _footer %>

var bodyParser = require("body-parser");
var cookieParser = require("cookie-parser");
var flash = require("connect-flash");
var passport = require("passport");
var session = require("express-session");
...
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(session({
    // 需要一串随机字母序列，字符串不一定需要跟此处一样
    secret: "TKRv0IJs=HYqrvagQ#&!F!%V]Ww/4KiVs$s,<<MX",
    resave: true,
    saveUninitialized: true
}));
app.use(flash());
app.use(passport.initialize());
app.use(passport.session());
...