@dvsa/database-helpers

database-operations

Database wrapper to help with connection creation and use of MyBatis, published as a GitHub package.

Pre-requisites

• Node.js (Please see .nvmrc for specific version)
• npm (If using n or nvm, this will be automatically managed)
• Security
  • Git secrets
  • ScanRepo
    • Unzip repo-security-scanner_<version>_Darwin_<architercture>.tar.gz and rename the executable inside the folder to scanrepo - Add executable to path (using echo $PATH to find your path)

Getting started

Run the following command after cloning the project

• npm install (or npm i)

The code that will be published lives inside the ./src directory.

If wishing to add new top level directories to the output, then they must be included in the files array inside package.json as well as included in the clean:temp command.

Publishing

In order to see the output of what will be published, run the following command:

npm publish --dry-run

There are two ways in which this package can/should be published:

Requires manual version bump via the PR

• Upon merge into main branch, the package will be published via a GHA workflow.

Contents

MyBatisSession

Overview

MyBatisSession is a utility class that integrates MyBatis mapping with MySQL, allowing for structured and efficient query execution. It supports query execution, result transformation, and silent error handling while providing debugging capabilities.

Usage

Importing the MyBatisSession Class

import { MyBatisSession } from "@dvsa/database-helpers";
import { createConnection } from "mysql2/promise";

Initializing a MyBatis Session

To use MyBatis, you need a MySQL connection, a namespace, and mapper files.

async function initializeSession() {
  const connection = await createConnection({
    host: "localhost",
    user: "root",
    password: "password",
    database: "test_db",
  });

  const session = new MyBatisSession(connection, "UserNamespace", ["./mappers/user.xml"], true);
  return session;
}

Executing a Query

async function fetchUsers() {
  const session = await initializeSession();
  const users = await session.query("getUsers", {});
  console.log("Users:", users);
  await session.end();
}

fetchUsers();

Selecting a Single Record and Mapping to a Model

class User {
  id!: number;
  name!: string;
}

async function getUserById(id: number) {
  const session = await initializeSession();
  const user = await session.selectOne("getUserById", { id }, User);
  console.log("User:", user);
  await session.end();
}

getUserById(1);

Selecting Multiple Records and Mapping to a Model

async function getAllUsers() {
  const session = await initializeSession();
  const users = await session.selectList("getAllUsers", {}, User);
  console.log("Users:", users);
  await session.end();
}

getAllUsers();

Handling Errors Silently

If you want to execute a query and return an empty array on failure, use selectAndCatchSilently.

async function getUsersSafely() {
  const session = await initializeSession();
  const users = await session.selectAndCatchSilently("getAllUsers", {}, User);
  console.log("Users:", users);
  await session.end();
}

getUsersSafely();

Closing the Connection

async function closeSession() {
  const session = await initializeSession();
  await session.end();
}

Debugging Mode

If debugMode is enabled (true), queries will be logged before execution.

*** Query for namespace: UserNamespace & mapperID: getUsers ***
SELECT * FROM users;
***

Error Handling

Errors will be thrown if:

• A query fails due to an invalid SQL statement or missing parameters.
• A MyBatis mapper file is incorrect.
• The MySQL connection is unavailable.

Using selectAndCatchSilently, errors will be logged but return an empty array.

try {
  const result = await session.query("invalidQuery", {});
} catch (error) {
  console.error("Error executing query:", error);
}