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Connector/Node.js Callback API

Connector/Node.js Callback API

There are two different connection implementations: one, the default, uses Promise and the other uses Callback, allowing for compatibility with the mysql and mysql2 API's. The documentation provided on this page follows Callback. If you want information on the Promise API, see the PROMISE API.

Quick Start

Install the mariadb Connector using npm

$ npm install mariadb

You can then use the Connector in your application code with the Callback API. For instance,

  const mariadb = require('mariadb/callback');
  const conn = mariadb.createConnection({host: 'mydb.com', user:'myUser', password: 'myPwd'});
  conn.query("SELECT 1 as val", (err, rows) => {
      console.log(rows); //[ {val: 1}, meta: ... ]
      conn.query("INSERT INTO myTable value (?, ?)", [1, "mariadb"], (err, res) => {
        console.log(res); // { affectedRows: 1, insertId: 1, warningStatus: 0 }
        conn.end();
      });
  });

Installation

In order to use the Connector, you first need to install it on your system. The installation process for Promise and Callback API is managed with the same package through npm.

$ npm install mariadb

To use the Connector, you need to import the package into your application code. Given that the Callback API is not the default, the require() statement is a little different.

const mariadb = require('mariadb/callback');

This initializes the constant mariadb, which is set to use the Callback API rather than the default Promise API.

Migrating from 2.x or mysql/mysql2 to 3.x

Default behaviour for decoding BIGINT / DECIMAL datatype for 2.x version and mysql/mysql2 drivers return a JavaScript Number object. BIGINT/DECIMAL values might not be in the safe range, resulting in approximate results.

Since 3.x version, the driver has a reliable default, returning:

  • DECIMAL => javascript String

  • BIGINT => javascript BigInt object

For compatibility with the previous version or mysql/mysql driver, four options have been added to return BIGINT/DECIMAL as number, as previous defaults.

option
description
type
default

insertIdAsNumber

Whether the query should return last insert id from INSERT/UPDATE command as BigInt or Number. default return BigInt

boolean

false

decimalAsNumber

Whether the query should return decimal as Number. If enabled, this might return approximate values.

boolean

false

bigIntAsNumber

Whether the query should return BigInt data type as Number. If enabled, this might return approximate values.

boolean

false

checkNumberRange

when used in conjunction of decimalAsNumber, insertIdAsNumber or bigIntAsNumber, if conversion to number is not exact, connector will throw an error (since 3.0.1)

function

Previous options supportBigNumbers and bigNumberStrings still exist for compatibility, but are now deprecated.

Other considerations

mysql has an experimental syntax permitting the use of ?? characters as placeholder to escape id. This isn't implemented in the mariadb driver, permitting the same query syntax for Connection.query and Connection.execute.

example:

  conn.query('call ??(?)', [myProc, 'myVal'], (err, res) => {});

has to use explicit escapeId:

  conn.query(`call ${conn.escapeId(myProc)}(?)`, ['myVal'], (err, res) => {});

Cluster configuration removeNodeErrorCount default to Infinity when mysql/mysql2 default to value 5. This avoids removing nodes without explicitly saying so.

Recommendation

Timezone consideration

Client and database can have a different timezone.

The connector has different solutions when this is the case. the timezone option can have the following value:

  • 'local' (default): connector doesn't do any conversion. If the database has a different timezone, there will be an offset issue.

  • 'auto' : connector retrieve server timezone. Dates will be converted if server timezone differs from client

  • IANA timezone / offset, example 'America/New_York' or '+06:00'.

IANA timezone / offset

When using IANA timezone, the connector will set the connection timezone to the timezone. this can throw an error on connection if timezone is unknown by the server (see mariadb timezone documentation, timezone tables might be not initialized) If you are sure the server is using that timezone, this step can be skipped with the option skipSetTimezone.

If the timezone corresponds to JavaScript default timezone, then no conversion will be done

Timezone setting recommendation.

The best is to have the same timezone on client and database, then keep the 'local' default value.

If different, then either client or server has to convert the date. In general, it is best to use client conversion to avoid putting any unneeded stress on the database. timezone has to be set to the IANA timezone corresponding to server timezone and disabled skipSetTimezone option since you are sure that the server has the corresponding timezone.

example: a client uses 'America/New_York' by default, and server 'America/Los_Angeles'. execute 'SELECT @@system_time_zone' on the server. that will give the server default timezone. the server can return POSIX timezone like 'PDT' (Pacific Daylight Time). IANA timezone correspondence must be found: (see IANA timezone List) and configure client-side. This will ensure DST (automatic date saving time change will be handled)

const mariadb = require('mariadb');
const conn = mariadb.createConnection({
            host: process.env.DB_HOST, 
            user: process.env.DB_USER, 
            password: process.env.DB_PWD,
            timezone: 'America/Los_Angeles',
            skipSetTimezone: true
});

Security consideration

Connection details such as URL, username, and password are better hidden into environment variables. using code like :

  const mariadb = require('mariadb');

  const conn = mariadb.createConnection({host: process.env.DB_HOST, user: process.env.DB_USER, password: process.env.DB_PWD});

Then, for example, run node.js setting those environment variables :

$ DB_HOST=localhost DB_USER=test DB_PASSWORD=secretPasswrd node my-app.js

Another solution is using dotenv package. Dotenv loads environment variables from .env files into the process.env variable in Node.js :

$ npm install dotenv

then configure dotenv to load all .env files

const mariadb = require('mariadb');
require('dotenv').config()
const conn = await mariadb.createConnection({
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PWD
});

with a .env file containing

DB_HOST=localhost
DB_USER=test
DB_PWD=secretPasswrd

.env files must NOT be pushed into the repository, using .gitignore

Alternatively, node.js 20.0 introduced the experimental feature of using the node --env-file=.env syntax to load environment variables without the need for external dependencies. WE can then simply write

const mariadb = require('mariadb');

const conn = await mariadb.createConnection({
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PWD
});

Assuming the presence of the same .env file as previously described.

Callback API

The Connector with the Callback API is similar to the one using Promise, but with a few differences.

Base:

Connection:

Pool:

PoolCluster

Base API

createConnection(options) → Connection

  • options: JSON/String Uses the same options as Promise API. For a complete list, see option documentation.

Returns a Connection object

Creates a new connection.

The difference between this method and the same with the Promise API is that this method returns a Connection object, rather than a Promise that resolves to a Connection object.

const mariadb = require('mariadb/callback');
const conn = mariadb.createConnection({
      host: 'mydb.com', 
      user:'myUser',
      password: 'myPwd'
    });
conn.connect(err => {
  if (err) {
    console.log("not connected due to error: " + err);
  } else {
    console.log("connected ! connection id is " + conn.threadId);
  }
});

Connection options

Essential options list:

option
description
type
default

user

User to access database.

string

password

User password.

string

host

IP address or DNS of the database server. Not used when using option socketPath.

string

"localhost"

port

Database server port number. Not used when using option socketPath

integer

3306

ssl

Enables TLS support. For more information, see the ssl option documentation.

mixed

database

Default database to use when establishing the connection.

string

socketPath

Permits connections to the database through the Unix domain socket or named pipe.

string

compress

Compresses the exchange with the database through gzip. This permits better performance when the database is not in the same location.

boolean

false

connectTimeout

Sets the connection timeout in milliseconds.

integer

1 000

socketTimeout

Sets the socket timeout in milliseconds after connection succeeds. A value of 0 disables the timeout.

integer

0

queryTimeout

Set maximum query time in ms (an error will be thrown if limit is reached). 0 or undefined meaning no timeout. This can be superseded for a query using timeout option

int

0

rowsAsArray

Returns result-sets as arrays, rather than JSON. This is a faster way to get results. For more information, see Query.

boolean

false

For more information, see the Connection Options documentation.

Connecting to Local Databases

When working with a local database (that is, cases where MariaDB and your Node.js application run on the same host), you can connect to MariaDB through the Unix socket or Windows named pipe for better performance, rather than using the TCP/IP layer.

In order to set this up, you need to assign the connection a socketPath value. When this is done, the Connector ignores the host and port options.

The specific socket path you need to set is defined by the socket server system variable. If you don't know it offhand, you can retrieve it from the server.

SHOW VARIABLES LIKE 'socket';

It defaults to /tmp/mysql.sock on Unix-like operating systems and MySQL on Windows. Additionally, on Windows, this feature only works when the server is started with the --enable-named-pipe option.

For instance, on Unix a connection might look like this:

const mariadb = require('mariadb/callback');
const conn = mariadb.createConnection({ socketPath: '/tmp/mysql.sock', user: 'root' });
conn.connect(err => {
  //do something with connection
  conn.end();
});

It has a similar syntax on Windows:

const mariadb = require('mariadb/callback');
const conn = mariadb.createConnection({ socketPath: '\\\\.\\pipe\\MySQL', user: 'root' });

createPool(options) → Pool

Returns a Pool object,

Creates a new pool.

Example:

const mariadb = require('mariadb/callback');
const pool = mariadb.createPool({ host: 'mydb.com', user: 'myUser', connectionLimit: 5 });
pool.getConnection((err, conn) => {
  if (err) {
    console.log("not connected due to error: " + err);
  } else {
    console.log("connected ! connection id is " + conn.threadId);
    conn.end(); //release to pool
  }
});

Pool options

Pool options includes connection option documentation that will be used when creating new connections.

Specific options for pools are :

option
description
type
default

acquireTimeout

Timeout to get a new connection from pool in ms.

integer

10000

connectionLimit

Maximum number of connection in pool.

integer

10

idleTimeout

Indicate idle time after which a pool connection is released. Value must be lower than @@wait_timeout. In seconds (0 means never release)

integer

1800

initializationTimeout

Pool will retry creating connection in loop, emitting 'error' event when reaching this timeout. In milliseconds

integer

acquireTimeout value

minimumIdle

Permit to set a minimum number of connection in pool. Recommendation is to use fixed pool, so not setting this value.

integer

set to connectionLimit value

minDelayValidation

When asking a connection to pool, the pool will validate the connection state. "minDelayValidation" permits disabling this validation if the connection has been borrowed recently avoiding useless verifications in case of frequent reuse of connections. 0 means validation is done each time the connection is asked. (in ms)

integer

500

noControlAfterUse

After giving back connection to pool (connection.end) connector will reset or rollback connection to ensure a valid state. This option permit to disable those controls

boolean

false

resetAfterUse

When a connection is given back to pool, reset the connection if the server allows it (only for MariaDB version >= 10.2.22 /10.3.13). If disabled or server version doesn't allows reset, pool will only rollback open transaction if any

boolean

true

leakDetectionTimeout

Permit to indicate a timeout to log connection borrowed from pool. When a connection is borrowed from pool and this timeout is reached, a message will be logged to console indicating a possible connection leak. Another message will tell if the possible logged leak has been released. A value of 0 (default) meaning Leak detection is disable

integer

0

Pool events

event
description

acquire

This event emits a connection is acquired from pool.

connection

This event is emitted when a new connection is added to the pool. Has a connection object parameter

enqueue

This event is emitted when a command cannot be satisfied immediately by the pool and is queued.

release

This event is emitted when a connection is released back into the pool. Has a connection object parameter

error

When pool fails to create new connection after reaching initializationTimeout timeout

Example:

pool.on('connection', (conn) => console.log(`connection ${conn.threadId} has been created in pool`));

createPoolCluster(options) → PoolCluster

Returns a PoolCluster object,

Creates a new pool cluster. Cluster handles multiple pools, giving high availability / distributing load (using round robin / random / ordered ).

Example:

const mariadb = require('mariadb/callback');

const cluster = mariadb.createPoolCluster();
cluster.add("master", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave2", { host: 'mydb3.com', user: 'myUser', connectionLimit: 5 });

//getting a connection from slave1 or slave2 using round-robin
cluster.getConnection(/^slave*$/, "RR", (err, conn) => {
  conn.query("SELECT 1", (err, rows) => {
     conn.end();
     return row[0]["@node"];
  });
});

PoolCluster options

Pool cluster options include pool option documentation that will be used when creating new pools.

Specific options for the pool cluster are :

option
description
type
default

canRetry

When getting a connection from pool fails, can cluster retry with other pools

boolean

true

removeNodeErrorCount

Maximum number of consecutive connection fail from a pool before pool is removed from cluster configuration. Infinity means node won't be removed. Default to Infinity since 3.0, was 5 before

integer

Infinity

restoreNodeTimeout

delay before a pool can be reused after a connection fails. 0 = can be reused immediately (in ms)

integer

1000

defaultSelector

default pools selector. Can be 'RR' (round-robin), 'RANDOM' or 'ORDER' (use in sequence = always use first pools unless fails)

string

'RR'

importFile(options[, callback])

Import an sql file

Example:

    mariadb.importFile({ host: 'localhost', user: 'root', file: '/tmp/tools/data-dump.sql'}, (err) => {
        if (err) console.log(err);
    });

version → String

Returns a String that is the library version. example '2.1.2'.

defaultOptions(options) → Json

Returns a JSON value containing options default value.

permit listing the default options that will be used.

const mariadb = require('mariadb');
console.log(mariadb.defaultOptions({ timezone: '+00:00' }));
/*
{
   host: 'localhost',
   port: 3306,
   user: 'root',
   password: undefined,
   database: undefined,
   collation: Collation { index: 224, name: 'UTF8MB4_UNICODE_CI', charset: 'utf8' },
   timezone: '+00:00',
   ...
}
*/

Connection API

connection.query(sql[, values][, callback]) -> Emitter

  • sql: string | JSON An SQL string value or JSON object to supersede default connections options. If a JSON object, it must have an "sql" property. For example: {dateStrings:true, sql:'SELECT NOW()'}

  • values: array | object Placeholder values. Usually an array, but in cases of just one placeholder, it can be given as is.

  • callback: function Callback function with arguments (error, results, metadata).

Returns an Emitter object that can emit four different types of event:

  • error: Emits an Error object, when query failed.

  • columns: Emits when columns metadata from result-set are received (parameter is an array of Metadata fields).

  • data: Emits each time a row is received (parameter is a row).

  • end: Emits when the query ends (no parameter).

Sends query to the database with a Callback function to call when done.

In cases where the query returns huge result-sets, this means that all data is stored in memory. You may find it more practical to use the Emitter object to handle the rows one by one, to avoid overloading memory resources.

For example, issuing a query with an SQL string:

connection.query("SELECT NOW()", (err, rows, meta) => {
  if (err) throw err;
  console.log(rows); //[ { 'now()': 2018-07-02T17:06:38.000Z } ]
});

Using JSON objects:

connection.query({dateStrings:true, sql:'SELECT now()'}, (err, rows, meta) => {
  if (err) throw err;
  console.log(rows); //[ { 'now()': '2018-07-02 19:06:38' } ]
});

Placeholder

To avoid SQL Injection attacks, queries permit the use of a question mark as a placeholder. The Connector escapes values according to their type. You can use any native JavaScript type, Buffer, Readable, or any object with a toSqlString method in these values. All other objects are stringified using the JSON.stringify method.

The Connector automatically streams objects that implement Readable. In these cases, check the values on the following server system variables, as they may interfere:

  • net_read_timeout: The server must receive the query in full from the Connector before timing out. The default value for this system variable is 30 seconds.

  • max_allowed_packet: Using this system variable, you can control the maximum amount of data the Connector can send to the server.

// Sends INSERT INTO someTable VALUES (1, _BINARY '.\'.st', 'mariadb')
connection.query(
  "INSERT INTO someTable VALUES (?, ?, ?)",
  [1, Buffer.from("c327a97374", "hex"), "mariadb"],
  (err, result) => {
	if (err) throw err;
	console.log(result);
	//log : { affectedRows: 1, insertId: 1, warningStatus: 0 }
  }
);

You can also issue the same query using Streaming.

const https = require("https");
https.get("https://node.green/#ES2018-features-Promise-prototype-finally-basic-support",
  readableStream => {
    connection.query("INSERT INTO StreamingContent (b) VALUE (?)", [readableStream], (err, res) => {
       if (err) throw err;
       //inserted
    });
  }
)

Query Results

Queries issued from the Connector return two different kinds of results: a JSON object and an array, depending on the type of query you issue. Queries that write to the database, such as INSERT, DELETE and UPDATE commands return a JSON object with the following properties:

  • affectedRows: An integer listing the number of affected rows.

  • insertId: An integer noting the auto-increment ID. In case multiple rows have been inserted, this corresponds to the FIRST auto-increment value.

  • warningStatus: An integer indicating whether the query ended with a warning.

connection.query(
  "CREATE TABLE animals (" +
	"id MEDIUMINT NOT NULL AUTO_INCREMENT," +
	"name VARCHAR(30) NOT NULL," +
	"PRIMARY KEY (id))",
  err => {
	connection.query("INSERT INTO animals(name) value (?)", ["sea lions"], (err, res) => {
	  if (err) throw err;
	  console.log(res);
	  //log : { affectedRows: 1, insertId: 1, warningStatus: 0 }
	});
  }
);

Result-set array

Queries issued from the Connector return two different kinds of results: a JSON object and an array, depending on the type of query you issue. When the query returns multiple rows, the Connector returns an array, representing the data for each row in the array. It also returns a meta object, containing query metadata.

You can format the data results using the nestTables and rowsAsArray options. By default, it returns a JSON object for each row.

connection.query('select * from animals', (err, res, meta) => {
  console.log(res); 
  // [ 
  //    { id: 1, name: 'sea lions' }, 
  //    { id: 2, name: 'bird' }, 
  //    meta: [ ... ]
  // ]  
});

Streaming

connection.query("SELECT * FROM mysql.user")
      .on("error", err => {
        console.log(err); //if error
      })
      .on("fields", meta => {
        console.log(meta); // [ ... ]
      })
      .on("data", row => {
        console.log(row);
      })
      .on("end", () => {
        //ended
      });

Piping

piping can be used using the.stream () function on a query that returns a Readable object that will emit rows objects.

const logRes = new Writable({
  objectMode: true,
  decodeStrings: false,
  write: (row, encoding, callback) => {
    console.log(row);
    callback();
  }
});

connection.query("SELECT * FROM mysql.user")
  .stream()
  .pipe(logRes);

connection.batch(sql, values [, callback])

  • sql: string | JSON SQL string value or JSON object to supersede default connections options. JSON objects must have an "sql" property. For instance, { dateStrings: true, sql: 'SELECT now()' }

  • values: array Array of parameter (array of array or array of object if using named placeholders).

  • callback: function Callback function with arguments (error, results, metadata).

callback either returns an [[#error|Error]] with results/metadata null or with error empty and results/metadata

Implementation depends of server type and version. for MariaDB server version 10.2.7+, the implementation uses dedicated bulk protocol.

For other, insert queries will be rewritten for optimization. example: insert into ab (i) values (?) with first batch values = 1, second = 2 will be rewritten insert into ab (i) values (1), (2).

If a query cannot be re-writen will execute a query for each value.

the result difference compared to executing multiple single query inserts is that only the first generated insert id will be returned.

For instance,

  connection.query(
    "CREATE TEMPORARY TABLE batchExample(id int, id2 int, id3 int, t varchar(128), id4 int)"
  );
  connection
    .batch("INSERT INTO `batchExample` values (1, ?, 2, ?, 3)", [[1, "john"], [2, "jack"]], (err, res) => {
      if (err) {
        console.log('handle error');
      } else {
      console.log(res.affectedRows); // 2
      }
    });

connection.beginTransaction([callback])

  • callback: function Callback function with argument Error if any error.

Begins a new transaction.

connection.commit([callback])

  • callback: function callback function with argument Error if any error.

Commits the current transaction if there is one active. The Connector keeps track of the current transaction state on the server. When there isn't an active transaction, this method sends no commands to the server.

connection.rollback([callback])

  • callback: function Callback function with argument Error if any error.

Rolls back the current transaction if there is one active. The Connector keeps track of the current transaction state on the server. Where there isn't an active transaction, this method sends no commands to the server.

conn.beginTransaction(err => {
  if (err) {
    //handle error
  } else {
    conn.query("INSERT INTO testTransaction values ('test')", (err) => {
      if (err) {
        //handle error
      } else {
        conn.query("INSERT INTO testTransaction values ('test2')", (err) => {
          if (err) {
            conn.rollback(err => {
              if (err) {
                //handle error
              }
            });
          } else {
            conn.commit(err => {
              if (err) {
                //handle error
              }
            });
          }
        });
      }
    })
  }
});

connection.changeUser(options[, callback])

Resets the connection and re-authenticates with the given credentials. This is the equivalent of creating a new connection with a new user, reusing the existing open socket.

conn.changeUser({user: 'changeUser', password: 'mypassword'}, err => {
  if (err) {
    //handle error
  } else {
    //connection user is now changed.
  }
});

connection.ping([callback])

  • callback: function Callback function with argument Error if any error.

Sends a one-byte packet to the server to check that the connection is still active.

conn.ping(err => {
  if (err) {
    //handle error
  } else {
    //connection is valid
  }
})

connection.end([callback])

  • callback: function Callback function with argument Error if any error.

Closes the connection gracefully. That is, the Connector waits for current queries to finish their execution, then closes the connection.

conn.end(err => {
  //handle error
})

connection.reset([callback])

  • callback: function Callback function with argument Error if any error.

reset the connection. Reset will:

  • rollback any open transaction

  • reset transaction isolation level

  • reset session variables

  • delete user variables

  • remove temporary tables

  • remove all PREPARE statement

This command is only available for MariaDB >=10.2.4 or MySQL >= 5.7.3. the function will be rejected with the error "Reset command not permitted for server XXX" if the server version doesn't permit reset.

For previous MariaDB version, reset connection can be done using connection.changeUser(options [, callback]) that do the same + redo authentication phase.

connection.isValid() → boolean

Returns a boolean

Indicates the connection state as the Connector knows it. If it returns false, there is an issue with the connection, such as the socket disconnected without the Connector knowing about it.

connection.destroy()

Closes the connection without waiting for any currently executing queries. These queries are interrupted. MariaDB logs the event as an unexpected socket close.

connection.escape(value) → String

This function permits escaping a parameter properly, according to a parameter type, to avoid injection. See mariadb String literals for escaping.

Escaping has some limitations:

  • doesn't permit Stream parameters

  • this is less efficient compared to using standard conn.query(), that will stream data to socket, avoiding string concatenation and using memory unnecessary

escape per type:

  • boolean: explicit true or false

  • number: string representation. ex: 123 => '123'

  • Date: String representation using YYYY-MM-DD HH:mm:ss.SSS format

  • Buffer: _binary''

  • object with toSqlString function: String an escaped result of toSqlString

  • Array: list of escaped values. ex: [true, "o'o"] => ('true', 'o\'o')

  • geoJson: MariaDB transformation to corresponding geotype. ex: { type: 'Point', coordinates: [20, 10] } => "ST_PointFromText('POINT(20 10)')"

  • JSON: Stringification of JSON, or if permitSetMultiParamEntries is enable, key escaped as identifier + value

  • String: escaped value, (\u0000, ', ", \b, \n, \r, \t, \u001A, and \ characters are escaped with '')

Escape is done for sql_mode value without NO_BACKSLASH_ESCAPES that disable \ escaping (default); Escaping API are meant to prevent SQL injection. However, privilege the use of connection.query(sql [, values][, callback]) and avoid building the command manually.

const myColVar = "let'go";
const myTable = "table:a"
const cmd = 'SELECT * FROM ' + conn.escapeId(myTable) + ' where myCol = ' + conn.escape(myColVar);
// cmd value will be:
// "SELECT * FROM `table:a` where myCol = 'let\\'s go'"

connection.escapeId(value) → String

This function permits escaping an Identifier properly. See Identifier Names for escaping. Value will be enclosed by '`' character if content doesn't satisfy:

  • ASCII: [0-9,a-z,A-Z$_] (numerals 0–9, basic Latin letters, both lowercase and uppercase, dollar sign, underscore)

  • Extended: U+0080 .. U+FFFF and escaping '`' character if needed.

const myColVar = "let'go";
const myTable = "table:a"
const cmd = 'SELECT * FROM ' + conn.escapeId(myTable) + ' where myCol = ' + conn.escape(myColVar);
// cmd value will be:
// "SELECT * FROM `table:a` where myCol = 'let\\'s go'"

// using template literals:
con.query(`SELECT * FROM ${con.escapeId(myTable)} where myCol = ?`, [myColVar], (err, rows) => { });

connection.pause()

Pauses data reads.

connection.resume()

Resumes data reads from a pause.

connection.serverVersion()

Returns a string

Retrieves the version of the currently connected server. Throws an error when not connected to a server.

  console.log(connection.serverVersion()); //10.2.14-MariaDB

connection.importFile(options[, callback])

  • options JSON: > ** file: file path (mandatory) > ** database: database if different that current connection database (optional)

  • callback function that returns an error if fails, nothing if success

Import sql file. If database is set, database will be use, then after file import, database will be reverted

    await conn.importFile({ file: '/tmp/someFile.sql', database: 'myDb'}, (err) => {
        if (err) {
            console.log(err);
        }
    });

Error

When the Connector encounters an error, Promise returns an Error object. In addition to the standard properties, this object has the following properties:

  • fatal: A boolean value indicating whether the connection remains valid.

  • errno: The error number.

  • sqlState: The SQL state code.

  • code: The error code.

Example on console.log(error):

{ Error: (conn:116, no: 1146, SQLState: 42S02) Table 'testn.falsetable' doesn't exist
  sql: INSERT INTO falseTable(t1, t2, t3, t4, t5) values (?, ?, ?, ?, ?)  - parameters:[1,0x01ff,'hh','01/01/2001 00:00:00.000',null]
      ...
      at Socket.Readable.push (_stream_readable.js:134:10)
      at TCP.onread (net.js:559:20)
    From event:
      at C:\mariadb-connector-nodejs\lib\connection.js:185:29
      at Connection.query (C:\mariadb-connector-nodejs\lib\connection.js:183:12)
      at Context.<anonymous> (C:\mariadb-connector-nodejs\test\integration\test-error.js:250:8)
    fatal: false,
    errno: 1146,
    sqlState: '42S02',
    code: 'ER_NO_SUCH_TABLE' } }

Errors contain an error stack, query, and parameter values (the length of which is limited to 1,024 characters, by default). To retrieve the initial stack trace (shown as From event... in the example above), you must have the Connection option trace enabled.

For more information on error numbers and SQL state signification, see the MariaDB Error Code documentation.

events

Connection object that inherits from the Node.js EventEmitter. Emits an error event when the connection closes unexpectedly.

  const conn = mariadb.createConnection({user: 'root', password: 'myPwd', host: 'localhost', socketTimeout: 100})
  conn.on('error', err => {
    //will be executed after 100ms due to inactivity, socket has closed. 
    console.log(err);
    //log : 
    //{ Error: (conn:6283, no: 45026, SQLState: 08S01) socket timeout
    //    ...
    //    at Socket.emit (events.js:208:7)
    //    at Socket._onTimeout (net.js:410:8)
    //    at ontimeout (timers.js:498:11)
    //    at tryOnTimeout (timers.js:323:5)
    //    at Timer.listOnTimeout (timers.js:290:5)
    //  fatal: true,
    //  errno: 45026,
    //  sqlState: '08S01',
    //  code: 'ER_SOCKET_TIMEOUT' }
  });

Pool API

Each time a connection is asked if the pool contains a connection that is not used, the pool will validate the connection, exchanging an empty MySQL packet with the server to ensure the connection state, then give the connection. The pool reuses connection intensively, so this validation is done only if a connection has not been used for a period (specified by the "minDelayValidation" option with the default value of 500ms).

If no connection is available, the request for a connection will be put in a queue until connection timeout. When a connection is available (new creation or released to the pool), it will be used to satisfy queued requests in FIFO order.

When a connection is given back to the pool, any remaining transactions will be rolled back.

pool.getConnection(callback)

Creates a new Connection object. Connection must be given back to pool with the connection.end() method.

Example:

const mariadb = require('mariadb/callback');
const pool = mariadb.createPool({ host: 'mydb.com', user:'myUser' });
pool.getConnection((err, conn => {
  if (err) {
    console.log("not connected due to error: " + err);
  } else {
    console.log("connected ! connection id is " + conn.threadId);
    conn.end(); //release to pool
  }
}));

pool.query(sql[, values][, callback])

  • sql: string | JSON SQL string or JSON object to supersede default connection options. When using JSON object, object must have an "sql" key. For instance, { dateStrings: true, sql: 'SELECT now()' }

  • values: array | object Placeholder values. Usually an array, but in cases of only one placeholder, it can be given as is.

  • callback: function Callback function with arguments (error, results, metadata).

This is a shortcut to get a connection from the pool, execute a query, and release the connection.

const mariadb = require('mariadb/callback');
const pool = mariadb.createPool({ host: 'mydb.com', user:'myUser' });
pool.query("SELECT NOW()", (err, results, metadata) => {
  if (err) {
    //handle error
  } else {
    console.log(rows); //[ { 'NOW()': 2018-07-02T17:06:38.000Z }, meta: [ ... ] ]
  }
});

pool.batch(sql, values[, callback])

  • sql: string | JSON SQL string or JSON object to supersede default connection options. When using JSON object, object must have an "sql" key. For instance, { dateStrings: true, sql: 'SELECT now()' }

  • values: array array of Placeholder values. Usually an array of array, but in cases of only one placeholder per value, it can be given as a single array.

  • callback: function Callback function with arguments (error, results, metadata).

This is a shortcut to get a connection from pool, execute a batch and release the connection.

const mariadb = require('mariadb/callback');
const pool = mariadb.createPool({ host: 'mydb.com', user:'myUser' });
pool.query(
  "CREATE TABLE parse(autoId int not null primary key auto_increment, c1 int, c2 int, c3 int, c4 varchar(128), c5 int)"
);
pool
  .batch("INSERT INTO `parse`(c1,c2,c3,c4,c5) values (1, ?, 2, ?, 3)", 
    [[1, "john"], [2, "jack"]],
    (err, res) => {
      if (err) {
        //handle error
      } else {
        //res = { affectedRows: 2, insertId: 1, warningStatus: 0 }
        assert.equal(res.affectedRows, 2);
        pool.query("select * from `parse`", (err, res) => {
            /*
            res = [ 
                { autoId: 1, c1: 1, c2: 1, c3: 2, c4: 'john', c5: 3 },
                { autoId: 2, c1: 1, c2: 2, c3: 2, c4: 'jack', c5: 3 },
                meta: ...
              }
            */ 
        });
      }
  });

pool.end([callback])

  • callback: function Callback function with argument (Error).

Closes the pool and underlying connections gracefully.

pool.end(err => {
  if (err) {
    //handle error
    console.log(err);
  } else {
    //connections have been ended properly    
  }
});

pool.escape(value) → String

This is an alias for connection.escape(value) → String to escape parameters

pool.escapeId(value) → String

This is an alias for connection.escapeId(value) → String to escape Identifier

pool.importFile(options[, callback])

  • options : > ** file: file path (mandatory) > ** database: database if different that current connection database (optional)

  • callback function that returns an error if fails, nothing if success

Import SQL file. If a database is set, the database will be used, then after file import, the database will be reverted to the initial value.

    pool.importFile({ file: '/tmp/someFile.sql', database: 'myDb'}, (err) => {
        if (err) console.log(err);
    });

Pool events

event
description

acquire

This event emits a connection is acquired from pool.

connection

This event is emitted when a new connection is added to the pool. Has a connection object parameter

enqueue

This event is emitted when a command cannot be satisfied immediately by the pool and is queued.

release

This event is emitted when a connection is released back into the pool. Has a connection object parameter

Example:

pool.on('connection', (conn) => console.log(`connection ${conn.threadId} has been created in pool`));

Pool cluster API

Cluster handles multiple pools according to patterns and handles failover / distributed load (round-robin / random / ordered).

poolCluster.add(id, config)

  • id: string node identifier. example : 'master'

  • config: JSON pool options to create pool.

Add a new Pool to the cluster.

Example:

const mariadb = require('mariadb/callback');
const cluster = mariadb.createPoolCluster();
cluster.add("master", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave2", { host: 'mydb3.com', user: 'myUser', connectionLimit: 5 });

poolCluster.remove(pattern)

  • pattern: string regex pattern to select pools. Example, "slave*"

remove and end pool(s) configured in the cluster.

poolCluster.end([callback])

  • callback: function Callback function with argument (Error).

Closes the pool cluster and underlying pools.

poolCluster(err => {
  if (err) {
    //handle error
    console.log(err);
  } else {
    //pools have been ended properly    
  }
});

poolCluster.getConnection([pattern, ][selector, ]callback)

  • pattern: string regex pattern to select pools. Example, "slave*". default '*'

  • selector: string pools selector. Can be 'RR' (round-robin), 'RANDOM' or 'ORDER' (use in sequence = always use first pools unless fails). default to the cluster option defaultSelector if set, 'RR' if not

  • callback: function Callback function with arguments (Error, Connection).

Creates a new Connection object. Connection must be given back to pool with the connection.end() method.

Example:

const mariadb = require('mariadb/callback');
const cluster = mariadb.createPoolCluster();
cluster.add("master", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave2", { host: 'mydb3.com', user: 'myUser', connectionLimit: 5 });
cluster.getConnection("slave*", (err, conn) => {
  //use connection and handle possible error
})

poolCluster events

PoolCluster object inherits from the Node.js EventEmitter. Emits 'remove' event when a node is removed from configuration if the option removeNodeErrorCount is defined (default to 5) and connector fails to connect more than removeNodeErrorCount times. (if other nodes are present, each attemps will wait for value of the option restoreNodeTimeout)

const mariadb = require('mariadb/callback');
const cluster = mariadb.createPoolCluster({ removeNodeErrorCount: 20, restoreNodeTimeout: 5000 });
cluster.add("master", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave2", { host: 'mydb3.com', user: 'myUser', connectionLimit: 5 });
cluster.on('remove', node => {
  console.log(`node ${node} was removed`);
})

poolCluster.of(pattern, selector) → FilteredPoolCluster

  • pattern: string regex pattern to select pools. Example, "slave*". default '*'

  • selector: string pools selector. Can be 'RR' (round-robin), 'RANDOM' or 'ORDER' (use in sequence = always use first pools unless fails). default to the

Returns :

Creates a new filtered pool cluster object that is a subset of cluster.

Example:

const mariadb = require('mariadb/callback')

const cluster = mariadb.createPoolCluster();
cluster.add("master-north", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("master-south", { host: 'mydb1.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1-north", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave2-north", { host: 'mydb3.com', user: 'myUser', connectionLimit: 5 });
cluster.add("slave1-south", { host: 'mydb2.com', user: 'myUser', connectionLimit: 5 });

const masterCluster = cluster.of('master*');
const northSlaves = cluster.of(/^slave?-north/, 'RANDOM');
northSlaves.getConnection((err, conn) => {
    //use that connection
});

filtered pool cluster

  • filteredPoolCluster.getConnection(callback) : Creates a new connection from pools that corresponds to pattern.

  • filteredPoolCluster.query(sql[, values][, callback]) : this is a shortcut to get a connection from pools that corresponds to pattern, execute a query and release connection.

PreviousConnector/Node.js Batch APINextConnector/Node.js Pipelining

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