MongoDB基本增删改查操作-基于Node.JS驱动
本文基于MongoDB
的Node.JS
驱动实现MongoDB
基本的增删改查操作。驱动官方文档见:mongodb.github.io/node-mongod…。
1 插入文档
MongoDB
中Collection
类的insertOne
和insertMany
方法用来插入文档。
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URl
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function() {
try {
await client.connect();
console.log('connected correctly to server');
const db = client.db(dbName);
// Insert a single document
let r = await db.collection('inserts').insertOne({
a: 1});
assert.equal(1, r.insertedCount);
// Insert multiple documents
r = await db.collection('inserts').insertMany([{
a: 2}, {
a: 3}]);
assert.equal(2, r.insertedCount);
// Close connection
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
第一个insert
语句向inserts
集合中插入单个文档,注意在MongoDB
中无需显示的创建集合inserts
,MongoDB
服务会在首次插入文档时自动创建该集合。 insertOne
和insertMany
方法接收第二个参数options
,可以配置写关注
、函数序列化
等参数,具体参数列表见:mongodb.github.io/node-mongod…。 例如下面这段代码会将传入的函数序列化并写入到副本集replica set
:
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function() {
try {
await client.connect();
console.log('connected correctly to server');
const db = client.db(dbName);
// Insert a single document
const r = await db.collection('inserts').insertOne({
a: 1,
b: function () {
return 'hello';}
}, {
w: 'majority',
wtimeout: 10000,
serializeFunctions: true,
forceServerObjectId: true
});
assert.equal(1, r.insertedCount);
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
2 更新文档
Collection
类的updateOne
和updateMany
方法用于实现更新操作。
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
// Get the updates collection
const col = db.collection('updates');
// Insert some documents
let r = await col.insertMany([{
a: 1}, {
a: 2}, {
a: 2}]);
assert.equal(3, r.insertedCount);
// Update a single document
r = await col.updateOne({
a: 1}, {
$set: {
b: 1}});
assert.equal(1, r.matchedCount);
assert.equal(1, r.modifiedCount);
// Update multiple documents
r = await col.updateMany({
a: 2}, {
$set: {
b: 2}});
assert.equal(2, r.matchedCount);
assert.equal(2, r.modifiedCount);
// Upsert a single document
r = await col.updateOne({
a: 3}, {
$set: {
b: 3}});
assert.equal(0, r.matchedCount);
assert.equal(1, r.upsertedCount);
// Close connection
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
updateOne
和updateMany
方法接收第三个参数options
,可以用来配置写关注
、更新并插入
等参数,具体参数列表见:mongodb.github.io/node-mongod…。
3 删除文档
Collection
类的deleteOne
和deleteMany
方法可以用来删除文档。
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
// Get the collection to remove
const col = db.collection('removes');
// Insert some documents
let r = await col.insertMany([{
a: 1}, {
a: 2}, {
a: 2}]);
assert.equal(3, r.insertedCount);
// Remove a single document
r = await col.deleteOne({
a: 1});
assert.equal(1, r.deletedCount);
// Remove multiple documents
r = await col.deleteMany({
a: 2});
assert.equal(2, r.deletedCount);
// Close connection
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
deleteOne
和deleteMany
方法可以接收第二个参数options
,用来配置写关注
等参数,具体参数列表见:mongodb.github.io/node-mongod…。
4 查询文档
查询MongoDB
的主要方法是find
方法。find
方法返回一个用来操作数据的游标
。下面的代码限制查询个数为2条文档,并使用toArray
方法导出文档。
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
// Get the collection
const col = db.collection('find');
// Insert some documents
const r = await col.insertMany([{
a: 1}, {
a: 1}, {
a: 1}]);
assert.equal(3, r.insertedCount);
// Get first two documents that match the query
const docs = await col.find({
a: 1}).limit(2).toArray();
assert.equal(2, docs.length);
// Close connection
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
方法find
返回的游标
支持各种链式调用,具体支持的方法见:mongodb.github.io/node-mongod…。 例如下面的代码使用游标
的next
方法进行迭代:
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
// Get the collection
const col = db.collection('find');
// Insert some documents
const r = col.insertMany([{
a: 1}, {
a: 1}, {
a: 1}]);
assert.equal(3, r.insertedCount);
// Get the cursor
const cursor = col.find({
a: 1}).limit(2);
// Iterate over the cursor
while(await cursor.hasNext()) {
const doc = cursor.next();
console.dir(doc);
}
// Close connection
client.close();
} catch(err) {
console.log(err.stack);
}
})();
复制代码
下面的代码使用游标
的each
方法进行迭代:
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database Name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
const col = db.collection('find');
const r = await col.insertMany([{
a:1}, {
a:1}, {
a:1}]);
assert.equal(3, r.insertedCount);
col.find({
a: 1}).limit(2).each((err, doc) => {
if (doc) {
console.dir(doc);
} else {
client.close();
return false;
}
});
} catch(err) {
console.log(err.stack);
}
})();
复制代码
5 投影
默认情况下,查询会返回文档的所有字段,可以通过投影(projection)
来限制MongoDB
服务返回的字段。投影配置文档
用来控制返回包含
哪些字段、不包含
哪些字段:
{ field1: <value>, field2: <value> ... }
复制代码
<value>
为0
或false
表示不包含,1
或true
表示包含。_id
字段默认返回,无需配置。除了_id
字段外,其他所有字段的配置不可以同时出现0
和1
。下面的例子仅返回age
字段:
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
// Connection URL
const url = 'mongodb://localhost:27017';
// Database Name
const dbName = 'myproject';
const client = new MongoClient(url);
(async function () {
try {
await client.connect();
console.log("Connected correctly to server");
const db = client.db(dbName);
const col = db.collection('project');
let r = await col.insertMany([{
name: 'Jim', age: 18}, {
name: 'Lucy', age: 16}]);
assert.equal(2, r.insertedCount);
r = await col.find({
name: 'Jim'}).project({
age: 1, _id: 0}).toArray();
console.log(r);
// Close connection
client.close();
} catch (err) {
console.log(err.stack);
}
})();
复制代码
还没有评论,来说两句吧...