@ssense/mysql

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MySQL Client

class Connection

Connection is a helper that makes it easy to access and send queries to a MySQL or MariaDB server. (see examples here)

Methods

Method	Returns	Description
constructor(options: ConnectionOptions)	Connection	Creates a new instance of Connection
query(sql: string, params?: any[])	Promise<any>	Sends a query to MySQL server and return a result
runInTransaction(callback: TransactionFunction)	Promise<any>	Executes a list of statements in a MySQL transactional way, managing the transaction (begin, commit, rollback) automatically
runWithLockTables(locks: LockTableOption[], callback: TransactionFunction)	Promise<any>	Same as runInTransaction() method, except it explicitly locks tables before running the transaction (calling LOCK TABLES instead of START TRANSACTION)
close()	Promise<void>	Closes all opened connections to the database and prevent new connections to be created

Details

constructor(options: ConnectionOptions)

Creates a new instance of Connection

Parameters

Name	Type	Required	Description
options	ConnectionOptions	Yes	The parameters used to connect to the MySQL server

ConnectionOptions properties

See here for more detail about options properties.

Name	Type	Required	Description
host	string	Yes	MySQL server hostname or IP address
database	string	Yes	Name of database to use
port	number	No	MySQL port (default: 3306)
user	string	No	MySQL username (default: null)
password	string	No	MySQL password (default: null)
connectionLimit	number	No	Maximum number of parallel connections in internal MySQL connection pool (default: 10)
timezone	string	No	The timezone configured on the MySQL server. This is used to type cast server date/time values to JavaScript Date object and vice versa. (default: 'local')

query(sql: string, params?: any[])

Sends a query to MySQL server and return a result

Parameters

Name	Type	Required	Description
sql	string	Yes	SQL query
params	any[]	No	SQL query params for a query with parameters (will be protected against SQL injections, see mysql npm module for more detail)

Return value

Type	Description
Promise<any>	Result of the executed query

runInTransaction(callback: TransactionFunction)

Executes a list of statements in a MySQL transactional way, managing the transaction (begin, commit, rollback) automatically

Parameters

Name	Type	Required	Description
callback	TransactionFunction	Yes	Function in which all the MySQL statements can be executed (will be run in a MySQL transaction)

TransactionFunction definition

TransactionFunction is a callback function that will be called with a transaction parameter, this transaction exposes a query function, which has the exact same profile as the query function above. You are therefore able to call transaction.query() to send MySQL queries in a transactional context. See examples for more detail.

Return value

Type	Description
Promise<any>	Result of the executed transaction

runWithLockTables(locks: LockTableOption[], callback: TransactionFunction)

Same as runInTransaction() method, except it explicitly locks tables before running the transaction (calling LOCK TABLES instead of START TRANSACTION)

Parameters

Name	Type	Required	Description
locks	LockTableOption[]	Yes	Array of LockTableOption (tables to lock with lock mode)
callback	TransactionFunction	Yes	Function in which all the MySQL statements can be executed (will be run in a MySQL transaction)

LockTableOption properties

Name	Type	Required	Description
name	string	Yes	Name of the table to lock
mode	'READ'|'WRITE'	Yes	Lock mode to use, must be one of 'READ' or 'WRITE'

TransactionFunction definition

Definition for TransactionFunction is available in runInTransaction() method above. See examples for more detail.

Return value

Type	Description
Promise<any>	Result of the executed transaction

close()

Closes all opened connections to the database and prevent new connections to be created

Examples

Transactional queries using runInTransaction()

import { Connection } from '@ssense/framework';

// Create connection
const connection = new Connection({ ...params });

// Run multiple MySQL commands inside a managed transaction
const result = await connection.runInTransaction(async (transaction) => {
    const users = await transaction.query('SELECT * FROM USERS');
    if (users.length > 0) {
        await transaction.query('UPDATE users set name=.....');
    }

    return users[0];
});

// result will be the object returned by the runInTransaction() method, here users[0]
// All the MySQL transaction commands (BEGIN, COMMIT or ROLLBACK) are automatically performed, so you just have to focus on your business case.

Transactional queries using runWithLockTables()

import { Connection } from '@ssense/framework';

// Create connection
const connection = new Connection({ ...params });

// Run multiple MySQL commands inside a managed transaction
const result = await connection.runWithLockTables(
    [
        { name: 'users', mode: 'WRITE' },
        { name: 'accounts', mode: 'WRITE' },
    ],
    async (transaction) => {
        // When reaching this part of the code, both "users" and "accounts" tables will be locked, even if we don't perfom any query on the "accounts" table
        const users = await transaction.query('SELECT * FROM USERS');
        if (users.length > 0) {
            await transaction.query('UPDATE users set name=.....');
        }

        return users[0];
    },
);

// result will be the object returned by the runWithLockTables() method, here users[0]
// All the MySQL transaction commands (BEGIN, COMMIT or ROLLBACK) are automatically performed, so you just have to focus on your business case.