# Connect From Node.js App Node.js developers can connect to MariaDB Cloud through a native MariaDB Connector. Using MariaDB Connector/Node.js you can connect to MariaDB Cloud to use and administer databases from within your Node.js application. ## Install MariaDB Connector/Node.js MariaDB Connector/Node.js is usually installed either from the Node.js repository or manually from the source code package. ## Install MariaDB Connector/Node.js via Repository To install MariaDB Connector/Node.js from the Node.js repository, use NPM: ```bash npm install mariadb ``` NPM connects to the Node.js repository and downloads MariaDB Connector/Node.js and all relevant dependencies into the `node_modules/` directory. ## Install MariaDB Connector/Node.js via Source Code To download and install the MariaDB Connector/Node.js manually from source code: 1. Go to the MariaDB Connectors download page: * 2. In the "Product" dropdown, select the Node.js connector. 3. Click the "Download" button to download the source code package 4. When the source code package finishes downloading, install it with NPM: `$ npm install mariadb-connector-nodejs-*.tar.gz` NPM untars the download and installs MariaDB Connector/Node.js in the `node_modules/` directory. ## Connect with MariaDB Connector/Node.js (Callback API) Node.js developers can use MariaDB Connector/Node.js to establish client connections with MariaDB Cloud. ## Require Callback API MariaDB Connector/Node.js provides two different connection implementations: one built on the [Promise API](https://mariadb.com/docs/connectors/mariadb-connector-nodejs/connector-nodejs-promise-api) and the other built on the Callback API. To use the Callback API, use the following module: ```js const** mariadb = require**(**'mariadb/callback'**); ``` ## Connecting ```js createConnection(options) -> Connection ``` This is the base function used to create a `Connection` object. The `createConnection(options)` function returns a `Connection` object. Determine the [connection information](/docs/mariadb-cloud/connecting-to-mariadb-cloud-dbs.md) for your MariaDB Cloud database service: | Option | Description | | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | host | The fully Qualified Domain Name from the "Connect" window in MariaDB Cloud portal | | port | The Read-Write Port or Read-Only Port from the "Connect" window in the MariaDB Cloud portal | | user | The desired username, which might be the default username in the Service Credentials view | | password | The user's password, which might be the default password in the Service Credentials view if it was not yet customized | | database | Database name to establish a connection to. No default is configured. | | connectTimeout | Connection timeout in milliseconds. In Connector/Node.js 2.5.6, the default value changed to 1000. The default value for earlier versions is 10000. | | rowsAsArray | A boolean value to indicate whether to return result sets as arrays instead of the default JSON. Arrays are comparatively faster. | ## Code Example: Connecting The following code example connects using the database and user account created in the [example setup](https://mariadb.com/docs/server/connect/programming-languages/c/example-setup/): ```jsx const mariadb = require('mariadb/callback'); // Certificate Authority (CA)", var serverCert = [fs.readFileSync(process.env.SKYSQL_CA_PEM, "utf8")]; // Declare async function function main() { let conn; try { conn = mariadb.createConnection({ host: "example.skysql.com", port: 5009, ssl: { ca: serverCert }, user: "db_user", password: "db_user_password", database: "test", }); // Use Connection // ... } catch (err) { // Manage Errors console.log("SQL error in establishing a connection: ", err); } finally { // Close Connection if (conn) conn.end(err => {if(err){ console.log("SQL error in closing a connection: ", err);} }); } } main(); ``` * A `try...catch...finally` statement is used for exception handling. * New connections are created in auto-commit mode by default. * When you are done with a connection, close it to free resources. Close the connection using the `connection.end([callback])` function. * The script calls the `connection.end([callback])` function to close/end the connection in the `finally` block after the queries that are running have completed. * The `end()` function takes a callback function that defines one implicit argument for the `Error` object if thrown in closing the connection as an argument. If no error is generated in closing a connection, the `Error` object is `null`. *** ## Connecting With MariaDB Connector/Node.js (Promise API) Node.js developers can use MariaDB Connector/Node.js to establish client connections with MariaDB Cloud. ## Require Promise API MariaDB Connector/Node.js provides two different connection implementations: one built on the Promise API and the other built on the [Callback API](https://github.com/mariadb-corporation/mariadb-connector-nodejs/blob/master/documentation/callback-api.md). Promise is the default. To use the Promise API, use the `mariadb` module: ```js const** mariadb = require**(**'mariadb'**); ``` ## Connecting `createConnection(options) -> Promise` is the base function used to create a `Connection` object. The `createConnection(options)` returns a `Promise` that resolves to a `Connection` object if no error occurs, and rejects with an `Error` object if an error occurs. Determine the [connection information](/docs/mariadb-cloud/connecting-to-mariadb-cloud-dbs.md) for your MariaDB Cloud database service: | Option | Description | | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | host | The fully Qualified Domain Name from the "Connect" window in the MariaDB Cloud portal | | port | The Read-Write Port or Read-Only Port from the "Connect" window in the MariaDB Cloud portal | | user | The desired username, which might be the default username in the Service Credentials view | | password | The user's password, which might be the default password in the Service Credentials view if it was not yet customized | | database | Database name to establish a connection to. No default is configured. | | connectTimeout | Connection timeout in milliseconds. In Connector/Node.js 2.5.6, the default value changed to 1000. The default value for earlier versions is 10000. | | rowsAsArray | A boolean value to indicate whether to return result sets as arrays instead of the default JSON. Arrays are comparatively faster. | Create a file named `.env` to store your database credentials: ```jsx # env 1 MDB_HOST = 192.0.2.50 MDB_PORT = 3306 MDB_USER = db_user MDB_PASS = db_user_password # env 2 MDB_HOST = example.skysql.com MDB_PORT = 5001 MDB_CA_PEM = /path/to/skysql_chain.pem MDB_USER = db_user MDB_PASS = db_user_password ``` ## Code Example: Connecting The following code example connects using the database and user account created in Setup for Examples: ```jsx // Required Modules const fs = require("fs"); const mariadb = require("mariadb"); require("dotenv").config() // Certificate Authority (CA) const serverCert = [fs.readFileSync(process.env.MDB_CA_PEM, "utf8")]; // Declare async function async function main() { let conn; try { conn = await mariadb.createConnection({ host: process.env.MDB_HOST, port: process.env.MDB_PORT, user: process.env.MDB_USER, password: process.env.MDB_PASS, ssl: { ca: serverCert }, database: "test", }); // Use Connection // ... } catch (err) { // Manage Errors console.log("SQL error in establishing a connection: ", err); } finally { // Close Connection if (conn) conn.close(); } } main(); ``` * Load the `mariadb` module using the `require()` function. * Declare an async function called `main()` using the `async` keyword. * An async function provides asynchronous, Promise-based code behavior. * Async functions may declare `await` expressions using the `await` keyword. * Await expressions yield control to a promise-based asynchronous operation. * Await expressions resume control after the awaited operation is either fulfilled or rejected. * The return value of an `await` expression is the resolved value of the `Promise`. * The async function name `main` is arbitrary and does not have a special meaning as in some other programming languages. * Declare a variable called `conn` for the connection to be created using a `let` statement with the async function `main`. * A `try...catch...finally` statement is used for exception handling. * New connections are by default created in auto-commit mode. * In the `try` block, create a new connection using the `mariadb#createConnection(options)` function in the Promise API. * Send error messages, if any, to the console in the `catch` block. * When you are done with a connection, close it to free resources. 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