sqlite-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.

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Table of Contents

• SqliteBatchEntityReader
• SqliteBatchEntityWriter

SqliteBatchEntityReader

extends AbstractBatchEntityReaderStream

Class that read data in batches of a specified size in SQLite databases.

Constructor

Name	Description	Type
options	The options for the SqliteBatchEntityReader.	SqliteBatchEntityReaderOptions
options.dbConnectionFactory	Function that creates a database connection.	function

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 finalizing the statement used to read entities and 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.<sqlite.Database>	A promise that resolves with the database connection.

disconnectDatabase (function)

Disconnects from the database by closing the active database connection and setting the connection 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 closed.

prepareStatement (function)

private

Prepares a statement for fetching entities. If the statement has already been prepared, it is reused.

Parameters

Name	Description	Type
db	The database connection.	sqlite.Database

Returns

Type	Description
Promise.<sqlite.Statement>	The prepared statement.

finalizeStatement (function)

private

Finalizes the statement used to fetch entities. This method should be called when the reader is no longer needed to free up resources.

SqliteBatchEntityWriter

extends AbstractBatchEntityWriterStream

Class that write data in batches of a specified size in SQLite databases.

Constructor

Name	Description	Type
options	The options for the SqliteBatchEntityWriter.	SqliteBatchEntityWriterOptions
options.dbConnectionFactory	Function that creates a database connection.	function

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.

executeBatch (function)

private

Executes a batch of data in the database, commits the transaction if all promises are resolved, or rolls back the transaction if any of the promises are rejected.

Parameters

Name	Description	Type
db	The database connection.	sqlite3.Database
chunk	The batch of data to write to the storage.	BatchData.<T>

Returns

Type	Description
Promise.<Array.<void>>	A promise that resolves when all promises are resolved.

commitTransaction (function)

private

Commits the transaction if no errors occurred during the batch execution. If an error occurred, the transaction is rolled back and the error is propagated.

Parameters

Name	Description	Type
db	The database connection.	sqlite.Database

Returns

Type	Description
Promise.<void>	A promise that resolves when the transaction is committed.

rollbackTransaction (function)

private

Rolls back the transaction if an error occurred during the batch execution. The error is propagated to the caller.

Parameters

Name	Description	Type
db	The database connection.	sqlite.Database

Returns

Type	Description
Promise.<void>	A promise that resolves when the transaction is rolled back.

prepareStatement (function)

private

Prepares a statement for saving entities. If the statement has already been prepared, it is reused.

Parameters

Name	Description	Type
db	The database connection.	sqlite.Database

Returns

Type	Description
Promise.<sqlite.Statement>	The prepared statement.

finalizeStatement (function)

private

Finalizes the statement used to save entities. This method should be called when the writer is no longer needed to free up resources.

_final (function)

private

Finalizes the writer by calling the _final method of the superclass and finalizing the statement used to save entities. This method should be called when the writer is no longer needed to free up resources.

Parameters

Name	Description	Type
callback	The callback function to be executed after finalizing the writer.	WriteCallback

Returns

Type	Description
Promise.<void>