TypeORM

TypeORM is an open-source ORM that lets you to manage and interact with your database. This guide covers the following topics:

• Connect to SerenDB from TypeORM

• Use connection pooling with TypeORM

• Connection timeouts

Connect to SerenDB from TypeORM

To establish a basic connection from TypeORM to SerenDB, perform the following steps:

1. Retrieve your SerenDB connection string. You can find the connection string for your database by clicking the Connect button on your Project Dashboard. Select a branch, a user, and the database you want to connect to. A connection string is constructed for you. The connection string includes the user name, password, hostname, and database name.

2. Update the TypeORM's DataSource initialization in your application to the following:

   import { DataSource } from 'typeorm';
   
   export const AppDataSource = new DataSource({
     type: 'postgres',
     url: process.env.DATABASE_URL,
     ssl: true,
     entities: [
       /*list of entities*/
     ],
   });

3. Add a DATABASE_URL variable to your .env file and set it to the SerenDB connection string that you copied in the previous step. We also recommend adding ?sslmode=require&channel_binding=require to the end of the connection string to ensure a secure connection.

   Your setting will appear similar to the following:

   DATABASE_URL="postgresql://[user]:[password]@[seren_hostname]/[dbname]?sslmode=require&channel_binding=require"

TypeORM leverages a [node-postgres](https://node-postgres.com) Pool instance to connect to your Postgres database. Installing [pg-native](https://npmjs.com/package/pg-native) and setting the `NODE_PG_FORCE_NATIVE` environment variable to `true` [switches the `pg` driver to `pg-native`](https://github.com/brianc/node-postgres/blob/master/packages/pg/lib/index.js#L31-L34), which, according to some users, produces noticeably faster response times.

Use connection pooling with TypeORM

Serverless functions can require a large number of database connections as demand increases. If you use serverless functions in your application, we recommend that you use a pooled SerenDB connection string, as shown:

# Pooled SerenDB connection string
DATABASE_URL="postgresql://alex:[e-mail]/dbname?sslmode=require&channel_binding=require"

A pooled SerenDB connection string adds -pooler to the endpoint ID, which tells SerenDB to use a pooled connection. You can add -pooler to your connection string manually or copy a pooled connection string from the Connect to your database modal, which you can access by clicking Connect on your Project Dashboard. Enable the Connection pooling toggle to add the -pooler suffix.

Connection timeouts

A connection timeout that occurs when connecting from TypeORM to SerenDB causes an error similar to the following:

Error: P1001: Can't reach database server at `ep-white-thunder-826300.us-east-2.aws.serendb.com`:`5432`
Please make sure your database server is running at `ep-white-thunder-826300.us-east-2.aws.serendb.com`:`5432`.

This error most likely means that the TypeORM query timed out before the SerenDB compute was activated.

A SerenDB compute has two main states: Active and Idle. Active means that the compute is currently running. If there is no query activity for 5 minutes, SerenDB places a compute into an idle state by default.

When you connect to an idle compute from TypeORM, SerenDB automatically activates it. Activation typically happens within a few seconds but added latency can result in a connection timeout. To address this issue, you can adjust your SerenDB connection string by adding a connect_timeout parameter. This parameter defines the maximum number of seconds to wait for a new connection to be opened. The default value is 5 seconds. A higher setting may provide the time required to avoid connection timeouts. For example:

DATABASE_URL="postgresql://[user]:[password]@[seren_hostname]/[dbname]?sslmode=require&channel_binding=require&connect_timeout=10"

A `connect_timeout` setting of 0 means no timeout.