Node.js 连接 MongoDB-7

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先安装模块:

npm install --save mongodb

当然,首先你要打开mongodb服务端:

mongod --bind_ip 127.0.0.1

创建数据库

要在 MongoDB 中创建一个数据库,首先我们需要创建一个 MongoClient 对象,然后配置好指定的 URL 和 端口号。

如果数据库不存在,MongoDB 将创建数据库并建立连接

在mongo客户端将mydatabase数据库创建出来:

> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
> use mydatabase
switched to db mydatabase
> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
> 

然后运行:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/mydatabase"; //连接服务端
MongoClient.connect(url, function(err, db) {
    if (err) throw err;
    console.log("数据库已创建!");
    db.close();
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
(node:26745) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
数据库已创建!

根据上面的警告,将添加相应的option,改为:

MongoClient.connect(url, { useNewUrlParser: true } ,function(err, db) {
    if (err) throw err;
    console.log("数据库已创建!");
    db.close();
});

返回:

数据库已创建!

 

创建集合

我们可以使用 createCollection() 方法来创建集合mycollection:

var MongoClient = require(mongodb).MongoClient;
var url = mongodb://localhost:27017/mydatabase;
MongoClient.connect(url, { useNewUrlParser: true }, function (err, db) {
    if (err) throw err;
    console.log(数据库已创建);
    var dbase = db.db("mydatabase");
    dbase.createCollection(mycollection, function (err, res) {
        if (err) throw err;
        console.log("创建集合!");
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
数据库已创建
创建集合!

客户端查看:

> show collections
mycollection

 

 

数据库操作( CURD )

插入数据

以下实例我们连接数据库 mydatabase 的 mycollection 表,并插入一条数据条数据,使用 insertOne():

mysql 不同的是 MongoDB 会自动创建数据库和集合,所以使用前我们不需要手动去创建。

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var myobj = { name: "菜鸟教程", url: "www.mydatabase" };
    dbo.collection("mycollection").insertOne(myobj, function(err, res) {
        if (err) throw err;
        console.log("文档插入成功");
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
文档插入成功

客户端查看:

> db.mycollection.find()
{
    "_id" : ObjectId("5c026cae5ae97668886fafaa"),
    "name" : "菜鸟教程",
    "url" : "www.mydatabase"
}

如果要插入多条数据可以使用 insertMany():

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var myobj = [
        { name: 菜鸟工具, url: https://c.runoob.com, type: cn},
        { name: Google, url: https://www.google.com, type: en},
        { name: Facebook, url: https://www.google.com, type: en}
    ];
    dbo.collection("mycollection"). insertMany(myobj, function(err, res) {
        if (err) throw err;
        console.log("文档插入成功");
        console.log("插入的文档数量为: " + res.insertedCount);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
文档插入成功
插入的文档数量为: 3

客户端查看:

> db.mycollection.find()
{ "_id" : ObjectId("5c026cae5ae97668886fafaa"), "name" : "菜鸟教程", "url" : "www.mydatabase" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3f"), "name" : "Google", "url" : "https://www.google.com", "type" : "en" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb40"), "name" : "Facebook", "url" : "https://www.google.com", "type" : "en" }

 

 

查询数据

可以使用 find() 来查找数据, find() 可以返回匹配条件的所有数据。 如果未指定条件,find() 返回集合中的所有数据。

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    dbo.collection("mycollection"). find({}).toArray(function(err, result) { // 返回集合中所有数据
        if (err) throw err;
        console.log(result);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[ { _id: 5c026cae5ae97668886fafaa,
    name: 菜鸟教程,
    url: www.mydatabase },
  { _id: 5c026d49ccbd816889e6bb3e,
    name: 菜鸟工具,
    url: https://c.runoob.com,
    type: cn },
  { _id: 5c026d49ccbd816889e6bb3f,
    name: Google,
    url: https://www.google.com,
    type: en },
  { _id: 5c026d49ccbd816889e6bb40,
    name: Facebook,
    url: https://www.google.com,
    type: en } ]

查询指定条件 name 为 "菜鸟教程" 的实例:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var whereStr = {"name":菜鸟教程}; // 查询条件
    dbo.collection("mycollection").find(whereStr).toArray(function(err, result) {
        if (err) throw err;
        console.log(result);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[ { _id: 5c026cae5ae97668886fafaa,
    name: 菜鸟教程,
    url: www.mydatabase } ]

 

 

更新数据

我们也可以对数据库的数据进行修改,以下实例将 name 为 "菜鸟教程" 的 url 改为 https://www.runoob.com:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var whereStr = {"name":菜鸟教程}; // 查询条件
    var updateStr = {$set: { "url" : "https://www.runoob.com" }};
    dbo.collection("mycollection").updateOne(whereStr, updateStr, function(err, res) {
        if (err) throw err;
        console.log("文档更新成功");
        db.close();
    });
});

客户端查看:

> db.mycollection.find()
{ "_id" : ObjectId("5c026cae5ae97668886fafaa"), "name" : "菜鸟教程", "url" : "https://www.runoob.com" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3f"), "name" : "Google", "url" : "https://www.google.com", "type" : "en" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb40"), "name" : "Facebook", "url" : "https://www.google.com", "type" : "en" }

如果要更新所有符合条的文档数据可以使用 updateMany():

 
var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var whereStr = {"type":en}; // 查询条件
    var updateStr = {$set: { "url" : "https://www.runoob.com" }};
    dbo.collection("mycollection").updateMany(whereStr, updateStr, function(err, res) {
        if (err) throw err;
        console.log(res.result.nModified + " 条文档被更新");
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
2 条文档被更新

客户端查看:

> db.mycollection.find()
{ "_id" : ObjectId("5c026cae5ae97668886fafaa"), "name" : "菜鸟教程", "url" : "https://www.runoob.com" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3f"), "name" : "Google", "url" : "https://www.runoob.com", "type" : "en" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb40"), "name" : "Facebook", "url" : "https://www.runoob.com", "type" : "en" }

 

 

删除数据

以下实例将 name 为 "菜鸟教程" 的数据删除 :

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var whereStr = {"name":菜鸟教程}; // 查询条件
    dbo.collection("mycollection").deleteOne(whereStr, function(err, obj) {
        if (err) throw err;
        console.log("文档删除成功");
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
文档删除成功

客户端查看:

> db.mycollection.find()
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3f"), "name" : "Google", "url" : "https://www.runoob.com", "type" : "en" }
{ "_id" : ObjectId("5c026d49ccbd816889e6bb40"), "name" : "Facebook", "url" : "https://www.runoob.com", "type" : "en" }

如果要删除多条语句可以使用 deleteMany() 方法

以下实例将 type 为 en 的所有数据删除 :

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var whereStr = { type: "en" }; // 查询条件
    dbo.collection("mycollection").deleteMany(whereStr, function(err, obj) {
        if (err) throw err;
        console.log(obj.result.n + " 条文档被删除");
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
2 条文档被删除

客户端查询:

> db.mycollection.find()
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }

 

 

排序

排序 使用 sort() 方法,该方法接受一个参数,规定是升序(1)还是降序(-1)。

例如:

{ type: 1 }  // 按 type 字段升序
{ type: -1 } // 按 type 字段降序

按 type 升序排列:

因为之前删的差不多了,再添加几条:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var myobj = [
        { name: 菜鸟工具, url: https://c.runoob.com, type: an},
        { name: Google, url: https://www.google.com, type: bn},
        { name: Facebook, url: https://www.google.com, type: dn}
    ];
    dbo.collection("mycollection"). insertMany(myobj, function(err, res) {
        if (err) throw err;
        console.log("文档插入成功");
        console.log("插入的文档数量为: " + res.insertedCount);
        db.close();
    });
});

客户端:

> db.mycollection.find()
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aac"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "an" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aad"), "name" : "Google", "url" : "https://www.google.com", "type" : "bn" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aae"), "name" : "Facebook", "url" : "https://www.google.com", "type" : "dn" }

然后排序:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var mysort = { type: 1 };
    dbo.collection("mycollection").find().sort(mysort).toArray(function(err, result) {
        if (err) throw err;
        console.log(result);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[ { _id: 5c0270aad64fbc6896311aac,
    name: 菜鸟工具,
    url: https://c.runoob.com,
    type: an },
  { _id: 5c0270aad64fbc6896311aad,
    name: Google,
    url: https://www.google.com,
    type: bn },
  { _id: 5c026d49ccbd816889e6bb3e,
    name: 菜鸟工具,
    url: https://c.runoob.com,
    type: cn },
  { _id: 5c0270aad64fbc6896311aae,
    name: Facebook,
    url: https://www.google.com,
    type: dn } ]

 

 

查询分页

首先客户端查看得到现在的存储状态:

> db.mycollection.find()
{ "_id" : ObjectId("5c026d49ccbd816889e6bb3e"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "cn" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aac"), "name" : "菜鸟工具", "url" : "https://c.runoob.com", "type" : "an" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aad"), "name" : "Google", "url" : "https://www.google.com", "type" : "bn" }
{ "_id" : ObjectId("5c0270aad64fbc6896311aae"), "name" : "Facebook", "url" : "https://www.google.com", "type" : "dn" }

如果要设置指定的返回条数可以使用 limit() 方法,该方法只接受一个参数,指定了返回的条数。

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    dbo.collection("mycollection").find().limit(2).toArray(function(err, result) {//只得到前两条数据
        if (err) throw err;
        console.log(result);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[ { _id: 5c026d49ccbd816889e6bb3e,
    name: 菜鸟工具,
    url: https://c.runoob.com,
    type: cn },
  { _id: 5c0270aad64fbc6896311aac,
    name: 菜鸟工具,
    url: https://c.runoob.com,
    type: an } ]

如果要指定跳过的条数,可以使用 skip() 方法。

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    dbo.collection("mycollection").find().skip(2).limit(2).toArray(function(err, result) {//跳过前两条数据,只得到后两条数据
        if (err) throw err;
        console.log(result);
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[ { _id: 5c0270aad64fbc6896311aad,
    name: Google,
    url: https://www.google.com,
    type: bn },
  { _id: 5c0270aad64fbc6896311aae,
    name: Facebook,
    url: https://www.google.com,
    type: dn } ]

 

 

 

连接操作

mongoDB 不是一个关系型数据库,但我们可以使用 $lookup 来实现左连接

例如我们有两个集合数据分别为:

先创建相应的集合:

集合1:orders

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var myobj = { _id: 1, product_id: 154, status: 1 };
    dbo.collection("orders").insertOne(myobj, function(err, res) {
        if (err) throw err;
        console.log("文档插入成功");
        db.close();
    });
});

客户端查看:

> db.orders.find()
{ "_id" : 1, "product_id" : 154, "status" : 1 }

 

集合2:products

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    var myobj = [
        { _id: 154, name: 笔记本电脑 },
        { _id: 155, name: 耳机 },
        { _id: 156, name: 台式电脑 }
    ];
    dbo.collection("products"). insertMany(myobj, function(err, res) {
        if (err) throw err;
        console.log("文档插入成功");
        console.log("插入的文档数量为: " + res.insertedCount);
        db.close();
    });
});

客户端查看:

> db.products.find()
{ "_id" : 154, "name" : "笔记本电脑" }
{ "_id" : 155, "name" : "耳机" }
{ "_id" : 156, "name" : "台式电脑" }
> 

 实现左连接:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://127.0.0.1:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    dbo.collection(orders).aggregate([{ 
        $lookup:{
            from: products, // 右集合
            localField: product_id, // 左集合 join 字段
            foreignField: _id, // 右集合 join 字段
            as: orderdetails // 新生成字段(类型array)
        }
    }]).toArray(function(err, res) {
        if (err) throw err;
        console.log(JSON.stringify(res));
        db.close();
    });
});

返回:

users-MacBook-Pro:test-mongodb user$ node index.js
[{"_id":1,"product_id":154,"status":1,"orderdetails":[{"_id":154,"name":"笔记本电脑"}]}]

即orders集合字段"product_id" : 154与products的_id相符合的products的数据将会为字段orderdetails的值,并存放到orders的数据内,然后返回一个值

 

 

删除集合

我们可以使用 drop() 方法来删除集合:

var MongoClient = require(mongodb).MongoClient;
var url = "mongodb://127.0.0.1:27017/";
MongoClient.connect(url, { useNewUrlParser: true }, function(err, db) {
    if (err) throw err;
    var dbo = db.db("mydatabase");
    dbo.collection("products").drop(function(err, delOK) { // 执行成功 delOK 返回 true,否则返回 false
        if (err) throw err;
        if (delOK) console.log("集合已删除");
        db.close();
    });
});

客户端查询:

> db.products.find()
> 

 

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