Node の MongoDB Driver

order

Prior to

《Node の MongoDB  install 》

  Among article , It mainly talks about how to install

MongoDB

And its visual interface

Compass

.

Now let's talk about node How to connect and use

MongoDB

, about node Connect , There are two ways , All download Libraries ：

• mongodb： MongoDB There is a basic library
  mongodb
  (Node.js MongoDB Driver)

• Mongoose:  Now the mainstream Library , Better in the amount of code , Just add, delete, modify and check the recommendation

mongodb

This is the basic library , But there are basic functions , If the demand is not too much, use this .

download

Installation command ：

yarn add mongodb

May refer to ：

https://www.mongodb.org.cn/drivers/5.html

Then create mongo The folder and index.js, It says in it

mongodb

How to use the library .

nodemon The main program running is main.js

Connect

First test mongodb Does the database exist , Whether it can be connected .

from

mongodb

Import... In the library

MongoClient

Client module , This module can be used to connect to the database

The test method is as follows ：( there baseUrl It is based on the address of the previous database , You can also view the database to be connected in the visual interface url)

const MongoClient = require('mongodb').MongoClient;

const baseUrl = 'mongodb://127.0.0.1:27017/mongodbTest'
function TestConnect() {
 MongoClient.connect(baseUrl, function(err, db) {
 if (err) throw err;
 console.log(" Database created !");
 db.close();
 });
}


function ：

But in fact, at this time, the database

mongodbTest

Not created , In the visual interface

compass

perhaps cmd None of them

then , I searched online for half a day , I found that this is only connected to 27017 Where? , No nonexistent database is created .（ The code in this rookie tutorial should be wrong ）

So let's create a database manually , You can create , A little bit more simple , Then you can create another set in the database .

Wait a minute , Next I'll go mongodb There was a wave of search on the official website , Finally, I successfully created the database with code , And the method on the rookie really doesn't work .

PS:  There is a boiling point here , And dig you gave a relatively complete reply , Ha ha ha

The previous test connection method can be slightly modified , Use async and await To carry out , This makes the code look more comfortable .

mongodb official API：

https://mongodb.github.io/node-mongodb-native/4.5/

It's used here

MongoClient.db

Method , This method will use or establish a database , however , If you don't create a collection for this database , Then this database will not be generated .

const baseUrl = 'mongodb://127.0.0.1:27017'
//  Create objects
const client = new MongoClient(baseUrl);

async function TestConnect() {
 try {
 //  Connect to database
 await client.connect();
 //  Use the previously manually created mongodbTest database
 const db = await client.db('mongodbTest');
 console.log(db.databaseName)

 //  Create a new collection  ( If the database is created by the code , Then you must create a set )
 db.createCollection('collection01')
 } catch(e) {
 console.log(e)
 await client.close();
 }
}

module.exports = { TestConnect }


Get collection list

Now that you have successfully created the database , Then try to get all the collection information under the database

collections

, have access to

collectionName

Print out the names of these sets

//  Connect to database
await client.connect();
//  Use the previously manually created mongodbTest database
const db = await client.db('mongodbTest');
//  Get all collections under the current database
let collections = await db.collections();
//  Print set name
collections.forEach(item=>{
 console.log(item.collectionName)
})


Set list name ：

After the above simple use of the database and set list , You can operate on a single set .

PS:  For the database db Please refer to specific API file , The methods inside are also relatively comprehensive

Create a collection and insert data

Use here db Medium

createCollection

Method , Can be used to create new collections

createCollection

Method parameter ：

Test code ：

//  Create a new collection
db.createCollection('collection03', { autoIndexId: true }, (err, res)=>{
 if (err) console.log(' Collection creation failed ');
 console.log(res.collectionName) // collection03
})

After creating an empty collection , It's time to insert data into this set

stay mongodb in , Most of the collections are documents , Or the front end can be regarded as a key value pair JSON data

example ： Define a document , And use

insertOne

Insert into the target set ：

//  Use set collection03
let c3 = db.collection('collection03');
//  Define documents
let doc = {
 name: ' Zhang San ',
 age: 18,
 hobby: ' Hit Li Si ',
}
//  Insert the document into the collection
const result = await c3.insertOne(doc);


insertOne If the insertion is successful , Will return the current document in the collection id

There are the following methods for inserting documents into collections 3 Kind of ：（ The return values of these three methods are Promise, have access to async and await To solve the callback ）

• insert：  Insert a single document or an array of documents MongoDB. If the incoming document does not contain \u id Field , The driver will add a , Thus changing the document

• insertMany：  Insert the document array MongoDB. If the incoming document does not contain \u id Field , The driver will add a , Thus changing the document

• insertOne：  Insert a single document MongoDB. If the incoming document does not contain \u id Field , The driver will add a , Thus changing the document

Next try inserting a document array ：

let doc = [
 {
 name: ' Li Si ',
 age: 18,
 hobby: ' Beat Wang Wu ',
 },
 {
 name: ' Wang Wu ',
 age: 18,
 hobby: ' Open three ',
 },
]
//  Insert the document into the collection
const result = await c3.insertMany(doc);


Read the data in the collection

The document content has been inserted into the database collection above , So how to read the data from the database ？

MongoDB

The library provides

find

Method

Example :  You need to use toArray Change my , Or you can use the callback method to view

//  Read the data in the collection
const res = await c3.find().toArray();
console.log(res)

If when retrieving data , You need to filter out some useless data , So it can be

find

Write parameters to configure .

Use here

projection

Limit the fields returned , Set the property that does not need to be read to 0, Or set the content to be read as 1.

Be careful , It is better not to set 0 and 1, Just set the read

perhaps

Do not read . Otherwise, there may be an error ：

MongoServerError: Cannot do inclusion on field name in exclusion projection

 （ If you specify 0 and 1 value , There will be errors , Unless one of the fields is \u id Field ）

The following example is to

_id

and

age

Do not read ：

//  Read the data in the collection
const res = await c3.find({}, { 
 projection: { _id: 0, age: 0 }
}).toArray();
console.log(res)

result ：

In the example above , Will find

find

The first parameter in the method is

{}

, Because this is the query object , Used to restrict search . You can use to filter .

query Example ：

//  Read the data in the collection
const res = await c3.find({
 name: / Zhang /
}, { 
 projection: { _id: 0, age: 0 }
}).toArray();
console.log(res)

In this way, only Zhang San's information is returned ：

Delete set information

Now try to delete the previously saved documents from the collection

There are also delete Delete method

//  Read the data in the collection
const res = await c3.deleteOne({
 name: / Zhang /
});
console.log(res) // { acknowledged: true, deletedCount: 1 }

Update collection

The above has been written with additions and deletions , Now? curd There are updates left

Example ：

//  Read the data in the collection
let newvalue = { $set: { hobby: ' Hit Li Si ' } }
const res = await c3.updateOne({
 name: / king /
}, newvalue);
console.log(res)


here , Wang Wu's hobby in the database has changed from playing Zhang San to playing Li Si

That's all mongodb Basic use of Library , I didn't expect to write so much .

mongoose Save it for next time ...