Shulou(Shulou.com)06/01 Report--

Listening to Chen Hongyu's "ideal Thirty". It sounds good.

The last two blog posts mentioned the installation and connection of Mongodb under Mac, this time let's take a look at how to operate Mongodb through Node.

PS: the data set in this article uses the "mycollection" from the 'test' library' in the previous blog post.

One: install the MongoDB package

To use the mongodb module in Node, you need to install oh ~ open the terminal and enter the following command ~

Npm install mongodb

Two: database connection and disconnection

1: introduce mongodb module

Var mongo = require ("mongodb")

2: create a server object for the MongoDB database

Var server = new mongo.Server (host,port, [options])

Description: host: server address, default local localhost;port: server port number, default 27017 position options: optional configuration parameter.

3: create a db object for MongoDB

Var db = new mongo.Db (databasename,server, [options])

Description: databasename: database name, here we use the "test" database in the previous article; server: server object; options: optional configuration parameters.

4: execute the open method of db and connect to the database

Db.open (callback (err,db))

Description: callback callback method. If the connection fails, an err error will be thrown, and a db object will be returned if the connection to the database is successful.

5: execute the close method of db to disconnect the database

Db.close ()

Note: when you close a database connection, a listening close event will be triggered. This event has two parameters, err and db, which have the same meaning as above.

Function (err,db) {

/ / callback method

}

Attached: code snippet. Save the following code in the testMongo.js file.

Var mongo = require ("mongodb")

Var host = "localhost"

Var port = "27017"

Var server = new mongo.Server (host,port, {auto_reconnect:true})

Var db = new mongo.Db ("test", server, {safe:true})

Db.open (function (err,db) {

If (err) {

Throw err

Console.log ("database connection error")

} else {

Console.log ("successfully establish a database connection")

Db.close ()

}

});

Db.on ("close", function (err,db) {

If (err) {

Throw err

Console.log ("database connection error")

} else {

Console.log ("close database connection")

}

})

Open a new terminal and type "mongod" to open mongodb.

Open a new terminal, type "node testMongo.js", see the following result, it is successful.

TestNode node testMongo.js

Successfully establish a database connection

Close the database connection

Three: data set

MongoDb operates on data collections! The operation of data is the operation of data set.

Db.collection (collectionname, [options], callback (err,collection))

Description: collectionname: the name of the data collection in the database, here is the "mycollection" in the previous section; options: optional configuration parameter. Callback: the callback method of the connection, which will have the err parameter of the connection error and the collecction parameter of the successful connection.

Attached: code snippet. Save the following file to testMongo.js.

Var mongo = require ("mongodb")

Var host = "localhost"

Var port = "27017"

Var server = new mongo.Server (host,port, {auto_reconnect:true})

Var db = new mongo.Db ("test", server, {safe:true})

Db.open (function (err,db) {

If (err) {

Throw err

Console.log ("database connection error")

} else {

Console.log ("successfully establish a database connection")

Db.collection ('mycollection',function (err,collection) {

If (err) {

Throw err

Console.log ("error connecting data set")

} else {

Console.log ("successfully connect data collection")

Db.close ()

}

});

}

});

Db.on ("close", function (err,db) {

If (err) {

Throw err

Console.log ("database connection error")

} else {

Console.log ("close database connection")

}

})

Open a new terminal, type "node testMongo.js", see the following result, it is successful.

TestNode node testMongo.js

Successfully establish a database connection

Successfully connect the data set

Close the database connection

Fourth: MongoDb- increase

The insert method of the data collection to realize the operation of adding data.

Collection.insert (docs, [options], [callback (err,docs)])

Description: docs: data to be inserted; options: optional configuration parameters. Optional callback: the callback method for insertion, the err parameter that is inserted incorrectly and the docs (inserted data) parameter when the insertion is successful.

Attached: code snippet. Save the following file to testMongo.js. -- insert 5 Cailala into the mycollection data collection of the test library

Var mongo = require ("mongodb")

Var host = "localhost"

Var port = "27017"

Var server = new mongo.Server (host,port, {auto_reconnect:true})

Var db = new mongo.Db ("test", server, {safe:true})

Db.open (function (err,db) {

If (err) {

Throw err

Console.log ("database connection error")

} else {

Console.log ("successfully establish a database connection")

Db.collection ('mycollection',function (err,collection) {

If (err) {

Throw err

Console.log ("error connecting data set")

} else {

Console.log ("successfully connect data collection")

/ / insert

For (var I = 1 position I)

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