Page Contents

Overview

LoopBack 3 datasources are compatible with LoopBack 4 datasources, so migrating datasources from LoopBack 3 to LoopBack 4 is simple.

In LoopBack 3, all datasources are defined in the server/datasources.json file, whereas in LoopBack 4 each datasource is defined in its own file in the src/datasources folder. Each LoopBack 4 datasource has a configuration file (e.g. mysql-ds.datasource.config.json) and a class file (e.g. mysql-ds.datasource.ts).

Migration Steps

To migrate a datasource from LoopBack 3 to LoopBack 4, complete the following steps:

  1. In the root of your LoopBack 4 application, use the lb4 datasource command to create a new datasource and enter the same datasource name as your LoopBack 3 application’s datasource (e.g. mysqlDs):

    $ lb4 datasource
    ? Datasource name: mysqlDs
    
  2. For the remaining prompts from the lb4 datasource command, use the defaults (press Enter for each one) since these will be replaced in the next step:

    ? Select the connector for mysqlDs: In-memory db (supported by StrongLoop)
    ? window.localStorage key to use for persistence (browser only):
    ? Full path to file for persistence (server only):
    
  3. Replace the contents of the newly created src/datasources/{dataSource.dataSourceName}.datasource.config.json file in your LoopBack 4 application with the datasource configuration from server/datasources.json in your LoopBack 3 application.

    For example, if your server/datasources.json file contains:

    {
      "mysqlDs": {
        "name": "mysqlDs",
        "connector": "mysql",
        "host": "demo.strongloop.com",
        "port": 3306,
        "database": "getting_started",
        "username": "demo",
        "password": "L00pBack"
      }
    }
    

    Move it to src/datasources/mysql-ds.datasource.config.json, so that it looks as follows:

    {
      "name": "mysqlDs",
      "connector": "mysql",
      "host": "demo.strongloop.com",
      "port": 3306,
      "database": "getting_started",
      "username": "demo",
      "password": "L00pBack"
    }
    
  4. Repeat steps 1-3 for each datasource you want to migrate.

Compatibility

As mentioned before, LoopBack 3 datasources are compatible with LoopBack 4 datasources. In both, a datasource is a connector instance that is used by legacy-juggler-bridge. For example, both a LoopBack 3 MySQL datasource and a LoopBack 4 MySQL datasource will use loopback-connector-mysql.