TypeORM how to seed database

Question

I am running my Node JS backend using typeorm ORM.

Coming from Entity Framework, it was very easy to seed the db with a few lines such as

Database.SetInitializer(new DbInitializer());  

Where the DbInitializer class would contain all the seeding info.

Is there a similar approach to seed the database in TypeOrm? If not, what is the recommended way of doing it?

1) Create a new migration with the data insertion statements? 2) Create a task where you instantiate and save entities?

Answer 1

Unfortunately, there is no officially released solution from TypeORM (at the time this answer was being published).

But there is a nice workaround we can use:

1. create another connection inside ormconfig.js file and specify another folder for "migrations" - in fact our seeds
2. generate and run your seeds with -c <connection name>. That's it!

Sample ormconfig.js:

module.exports = [   {     ...,     migrations: [       'src/migrations/*.ts'     ],     cli: {       migrationsDir: 'src/migrations',     }   },   {     name: 'seed',     ...,     migrations: [       'src/seeds/*.ts'     ],     cli: {       migrationsDir: 'src/seeds',     }   } ] 

Sample package.json:

{   ...   scripts: {     "seed:generate": "ts-node typeorm migration:generate -c seed -n ",     "seed:run": "ts-node typeorm migration:run -c seed",     "seed:revert": "ts-node typeorm migration:revert -c seed",   },   ... } 

Answer 2

I would love to see such functionality as well (and we're not alone), but at the moment, there's no official feature for seeding.

in lack of such a built-in feature, I think the next best thing would be to create a migration script named 0-Seed (so it precedes any other migration scripts you might have) and have the seed data populated there.

@bitwit has created a snippet that may come in handy for you; it's a function that reads the data from yaml files, which you can incorporate in the seed migration script.

after some research, however, I found another interesting approach: bind an after_create event to the table, and initialize the data in the listener.
I haven't implemented this, so I'm not sure it can be done directly with TypeORM.