unable to set migration strategy per model

[chestercharles]

Sails version: 1.0.2
Node version: 8.9.4
NPM version: 6.1.0
DB adapter name: sails-disk
DB adapter version: version that ships with sails 1.0.2
Operating system: Windows 8.1 Enterprise

---

Howdy,

I've started to use Sails v1 for new projects after using v0.12 for many previous projects. In v0.12, I set a migration strategy I wanted to use for my models in config/models.js.

/**
 * Default model settings
 * (sails.config.models)
 */
module.exports.models = {
    migrate: 'drop',
}

For a given model, I could set a different migration strategy in that model file (eg. api/models/Kitten.js) that would override what was in config/models.js.

/**
 * Kitten.js
 *
 * @description :: A model definition.  Represents a database table/collection/etc.
 * @docs        :: https://sailsjs.com/docs/concepts/models-and-orm/models
 */
module.exports = {
    migrate: 'safe',
    attributes: {
       
    }
}

When the server lifted, it would honor this model-specific migration strategy, and leave my kittens data intact.

Is this no longer the default behavior in v1.x? I do not see this on the list of breaking changes when upgrading to v1.

Steps to reproduce (or see this repo):

1. Generate a new app: sails generate new testapp1
2. Create a kitten model: sails generate model kitten
3. Create a puppy model: sails generate model puppy
4. Set migrate: 'drop' in config/models.js
5. Start sails with node app.js
6. Hit http://localhost:1337/kitten/create a couple times to generate some kittens.
7. Shut down sails
8. Add migrate: 'safe to api/models/Kitten.js
9. Start sails with node app.js
10. Go to http://localhost:1337/kitten... we've lost all the kittens.

[sailsbot]

@chestercharles Thanks for posting, we'll take a look as soon as possible.

---

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[johnabrams7]

@chestercharles The Sails v1.0 breaking changes log states, "The experimental create auto-migration scheme is no longer supported. It is highly recommended that you use a migration tool such as Knex to handle migrations of your production database." Hope this helps!

[chestercharles]

@johnabrams7 , I don't think the "create auto-migration scheme" is what I'm trying to use, here. I just want to be able to use different migration strategies for different models.

For example, in my case I have a User model which uses a datastore that is actually a web service that pulls data for employees at my company. I want to configure the model so that it always uses the safe migration strategy

The Model Settings documentation state they "can be specified on a per-model basis by setting top-level properties in a model definition". I would assume this includes the migrate setting.

[chestercharles]

After digging into the sails-hook-orm, it appears that auto-migrations are performed using whatever migration strategy is set in sails.config.models.migrate:
https://github.com/balderdashy/sails-hook-orm/blob/master/lib/build-ontology-and-run-auto-migrations.js#L132

    // Now that all relevant attributes have `autoMigrations` properties set, go ahead
    // and perform any requested migrations.
    WaterlineUtils.autoMigrations(sails.config.models.migrate, freshOntology, function(err) {
      if (err) { return done(err); }

      return done(undefined, freshOntology);
    });

I would expect that the orm hook would also inspect the migrate setting of each model, and perform the corresponding auto migration strategy for that model.

[raqem]

Hi @chestercharles,
I am looking into your issue more (thanks alot for adding a repo so I can easily test it out!) The first thing I am noticing is that in your config/models.js you have migrate set to drop. What that means is that every time you shut down Sails you are telling it to drop your data! So all your kittens are lost because its wiping your data clean!
I think you want to start with your migrate: 'alter' and see where that gets you!
But note that this migrate setting is only to be used locally in test environmants. Like it states in the models file once you are in production Sails will treat all models as if they are set to safe.

Also here are the official docs for migration for easy access:
https://sailsjs.com/documentation/concepts/models-and-orm/model-settings#?migrate

[chestercharles]

Hi @raqem, thanks for looking into the issue.

My confusion is not about what the different migration strategies do, but rather why Sails no longer supports migrate as a top level model property.

The documentation says:

Model settings allow you to customize the behavior of the models in your Sails app. They can be specified on a per-model basis by setting top-level properties in a model definition, or as app-wide defaults in sails.config.models.

However, in Sails v1 this is not the case - the migrate setting cannot be set on a per-model basis. It can only be set as an app-wide default in sails.config.models.

In Sails v0.12.9 I was able to have a different migrate setting per each model - this was very helpful when I had different models using different connections (datastores) that may or may not be read-only. I've modified my initial repo to include another puppy/kitten app generated with Sails v0.12.9 to demonstrate this.

I could certainly be misunderstanding something, but this appears to be a breaking change?

[chestercharles]

Hi @raqem. Does my previous question make sense? Have you and your team had a chance to take a look at this yet?

[krewx]

I have the same issue that @chestercharles it's commenting. I have the inverse situation, my db is so big that my migration it's on safe and i want to alter or drop certain models but keep safe migration for the rest of the models.

[chestercharles]

I've been working around this by making the drop and define methods fail silently in my custom adapters for read only data:

define: function (datastoreName, tableName, definition, done) {
    logger.warn(`Adapter method ('define') not implemented in this adapter.`)
    return done();
  },

However, this is a sloppy hack and would not work in @krewx 's situation.

Does Sails plan to support setting migration strategies per model?

[raqem]

Hi @chestercharles,
So sorry for the long delay! I am going to tackle someone today until I can get some kind of satisfactory answer for you before the holiday!

[chestercharles]

@raqem thanks! But dont hurt anyone on my account! 😳

[raqem]

Hey @chestercharles @krewx,
Its official, Sails V1 does not support setting each model to its own migration schema.

It was there in the docs all along but apparently a little too easy to read over since I swear I read that page a half-dozen times.

My understanding is that this was done to avoid having a situation where associated models have different migration strategies and by one slip up become a massive tangle and database death-heap.