Migrating built-in models to Databases

Question

How to move built-in models like User, Roles, User-Role-Mapping etc... to the database we've created instead of the default datasource:db? The built-in models are not listing in Arc.

I've tried creating a new model which inherits these base model. But, data is not saved into the new model.

Please advice...I've been sitting on it for a couple of weeks. Thanks

Justino

Answer 1

Default "db" datasource is placed in memory. That is why your data are not persisted after you restart application. You have to install appropriate database connector and then you have to add datasource for your database inside server/datasources.js.

http://docs.strongloop.com/display/public/LB/Connecting+models+to+data+sources

If you created application with "slc loopback" command, then your datasource contains only memory connector. Check datasources.js file and you will see something like this:

{
  "db": {
  "name": "db",
  "connector": "memory"
  }
}

If you want to persist your data for example in postgresql database (process is almost same for any supported connector), you have to expand your datasoruces.json file with your database information:

{
  "db": {
  "name": "db",
  "connector": "memory"
  },

  "mydata": {
    "host": "db_host",
    "database": "your_database_name",
    "username": "your_db_username",
    "password": "your_db_password",
    "connector": "postgresql"
  }
}

You can also do this using "slc loopback:datasource" command. Wizard will help you to define your datasource. Don't forget to install db connector.

npm install loopback-connector-postgresql

Last thing to do is to assign your datasource to desired models. You can do this using wizard (see slc loopback:model command), or you can edit server/model-config.json file manually.

{
  "User": {
    "dataSource": "mydata",
    "public": true
  },
  "AccessToken": {
    "dataSource": "mydata",
    "public": false
  },
  "ACL": {
    "dataSource": "mydata",
    "public": false
  },
  "RoleMapping": {
    "dataSource": "mydata",
    "public": false
  },
  "Role": {
    "dataSource": "mydata",
    "public": false
  }
}

UPDATE You can try this code snippet to update your tables from models. Put his code somewhere in server/server.js

var appModels = ['User', 'AccessToken', 'ACL', 'RoleMapping', 'Role'];

var ds = app.dataSources.mydata;
ds.isActual(appModels, function(err, actual) {
  if (!actual) {
    ds.autoupdate(appModels, function(err) {
      if (err) throw (err);
    });
  }
});

I would recommend you to read about creating/updating database schema from models on strongloop page. Pay attention abut difference between autoupdate and automigrate functions

http://docs.strongloop.com/display/public/LB/Creating+a+database+schema+from+models

Phobos

Thank you for your reply. I've already tried the same. Only one problem: I can't migrate this to the database. I've tried using Arc and cli command. – Justino

Can you explain with more details what you have tried? – Phobos

I have updated answer with some code and link to docs where you can read more about updating schema from models. – Phobos

Oh Great! It worked. I pasted the code in your update and it worked. – Justino

What if I need to create migrations in different models at the same time and the result of one migration is the new records in another migration? that's a real scenario when a migration result has to be inserted in another table as a related model. for example you insert a new user and the returned id is the new registry for subscriptions table which has a subscription plan and a userId. for example, how would it look like? – Rico

@LuisParada Migration as discussed here is about database schema migration. You should ask another question about creating/migrating data. – Phobos