Javascript TypeORM ConnectionNotFoundError
Understanding TypeORM
TypeORM is a popular Object-Relational Mapper (ORM) for TypeScript and JavaScript applications. It is designed to work with various databases, providing a seamless way to interact with database records using TypeScript or JavaScript objects. TypeORM supports both Active Record and Data Mapper patterns, making it flexible for different project needs.
Identifying the Symptom: ConnectionNotFoundError
When working with TypeORM, you might encounter the ConnectionNotFoundError. This error typically occurs when TypeORM cannot find a connection with the specified name. The error message might look like this:
Error: ConnectionNotFoundError: Connection "default" was not found.
Exploring the Issue: What Causes ConnectionNotFoundError?
The ConnectionNotFoundError is thrown when TypeORM attempts to use a connection that hasn't been established or is incorrectly configured. This can happen due to several reasons:
- The connection name specified in your code does not match any connection defined in your TypeORM configuration.
- The connection setup process was not completed before attempting to use the connection.
- There is a typo or misconfiguration in your connection settings.
Common Scenarios Leading to the Error
Developers often encounter this error when they forget to call the createConnection function or when the connection name is misspelled in the configuration or usage.
Steps to Resolve ConnectionNotFoundError
To resolve the ConnectionNotFoundError, follow these steps:
Step 1: Verify Connection Configuration
Ensure that your TypeORM configuration file (e.g., ormconfig.json or ormconfig.js) is correctly set up. Check that the connection name matches the one you are using in your application code. Here is an example configuration:
{
"type": "postgres",
"host": "localhost",
"port": 5432,
"username": "test",
"password": "test",
"database": "test",
"synchronize": true,
"logging": false,
"entities": ["src/entity/**/*.ts"],
"migrations": ["src/migration/**/*.ts"],
"subscribers": ["src/subscriber/**/*.ts"],
"cli": {
"entitiesDir": "src/entity",
"migrationsDir": "src/migration",
"subscribersDir": "src/subscriber"
}
}
Step 2: Establish the Connection
Before using the connection, ensure it is established by calling createConnection. This is typically done at the start of your application:
import { createConnection } from "typeorm";
createConnection().then(connection => {
// Start using the connection
}).catch(error => console.log("Error: ", error));
Step 3: Check for Typos and Misconfigurations
Double-check your connection name and ensure it matches exactly with what is defined in your configuration. Even a small typo can lead to this error.
Step 4: Use Default Connection Name
If you are using the default connection, ensure that you are not specifying a connection name in your code, or if you do, it should be "default".
Additional Resources
For more information on setting up and configuring TypeORM, you can refer to the official TypeORM documentation. If you are new to TypeORM, consider checking out this guide on connections to get started.
Try DrDroid: AI Agent for Debugging
Try DrDroid: AI Agent for Fixing Production Errors
MORE ISSUES
Backed by
