mysql-api.md

Common API

In this documentation, we will focus on the common API. This module includes the core of BatchJS. This API allows you to create your own custom jobs and steps using the common interface.

---

Table of Contents

• MysqlBatchEntityReader
• MysqlBatchEntityWriter

MysqlBatchEntityReader

extends AbstractBatchEntityReaderStream

Class that reads data in batches of a specified size from a MySQL database.

Constructor

Name	Description	Type
options	The options for the MysqlBatchEntityReader.	MysqlBatchEntityReaderOptions
options.pool	The MySQL connection pool.	Pool
options.query	SQL query to be executed (without LIMIT and OFFSET).	string

fetch (function)

private

Fetches a batch of data from the database.

Parameters

Name	Description	Type
size	The size of the batch to fetch.	number

Returns

Type	Description
Promise.<BatchData.<T>>	A promise that resolves with the batch of data.

_destroy (function)

private

Destroys the writer by closing the database connection. This method should be called when the writer is no longer needed to free up resources.

Parameters

Name	Description	Type
error	The error that caused the destruction.	Error, null
callback	The callback function to be executed after destroying the reader.	ReadCallback

connectDatabase (function)

private

Connects to the database by creating a new database connection if none already exists, or by reusing an existing connection.

Returns

Type	Description
Promise.<PoolConnection>	A promise that resolves with the database connection.

disconnectDatabase (function)

Disconnects from the database by releasing the active database connection and setting the client reference to null. This method should be called when the reader is no longer needed to free up resources.

Returns

Type	Description
Promise.<void>	A promise that resolves when the database connection
is successfully released.

MysqlBatchEntityWriter

extends AbstractBatchEntityWriterStream

Class that writes data in batches of a specified size into a MySQL database.

Constructor

Name	Description	Type
options	The options for the MysqlBatchEntityWriter.	MysqlBatchEntityWriterOptions
options.pool	The MySQL connection pool.	Pool
options.prepareStatement	Insert SQL prepared statement to be executed.	String

batchWrite (function)

protected

Writes a batch of data to the storage.

Parameters

Name	Description	Type
chunk	The batch of data to write to the storage.	BatchData.<T>

Returns

Type	Description
Promise.<void>	A promise that resolves when the batch is successfully written.
The promise should be rejected if there is an error during writing.