sails.js - I want to add DB connection dynamically after sails lift

Question

During sails lift I don't yet have all the connection information for my DB.

Is there a way to either have config values dependent on promises or dynamically create a connection after sails lift has completed?

I would obviously have to add a policy or hook to handle requests to routes needing the model if it wasn't available yet, but at this point I don't see how to even let the sails lift until I already know the connection info (it must be in the configs).

I'm hoping I'm missing a way to dynamically create connections and wire models to them.

Answer 1

Update: In Sails v1.0 / Waterline v0.13, this can be accomplished by accessing the stateless, underlying driver; e.g. sails.getDatastore().driver. This can be used in any database adapter that supports the new stateless driver interface, including MySQL, PostgreSQL, and MongoDB.

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Prior to Sails v1.0, this was not officially supported in Sails or Waterline directly, but depending on your use case there are a couple of good solutions for this. If your use case is a handful of dynamic connections for the purpose of development (e.g. in an auto-reload plugin), and you're willing to live on the edge, you can take advantage of a private API as an immediate-term workaround: sails.hook.orm.reload(). However you definitely don't want to use that in production since it literally flushes the entire ORM.

If you are going to be dealing with a larger number (let's say > 10 unique configurations) of runtime-dynamic datastore configurations during the lifetime of the running Node process, that's a different story. In that case, I would recommend using the relevant raw driver (e.g. https://github.com/felixge/node-mysql) to summon/release those dynamic connections from a pool directly via a service. You can still use your normal models in your app for connections which are static-- you will just be best off implementing dynamic database connections separately in your service. For example, if you were building a hosted version of phpMyAdmin you might use a lower-level NPM package to dynamically fetch information about users' tables, but you'd still probably want to have Account and Database models that refer to tables/collections stored in your own database.

A more integrated solution for Sails is in the works. This ability to tap into the raw connection lifecycle and access it from userland is a prerequisite for built-in transaction support, which is something we expect to land in Sails/Waterline some time in the second half of 2016. In the mean time, if you encapsulate your logic to summon/release connections via service methods as suggested above, you'll have a working solution for now and your business logic should be more or less future proof (when you upgrade, you'll just need to swap out the implementation in your service). Hope that helps!