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Stores (storage backends — advanced)

note

Store is the internal infrastructure that owns a backend instance (a DB connection or pool, a bucket) and produces Repositories. Application code uses Repositories — Model.create() / Model.ref(uuid).get() / Model.query() or useRepository(Model) — and never references a Store by name. This page is for store-package authors and power-user paths. The Store class and StoreParameters are tagged @internal.

The store services allow you to store object in a NoSQL database it handles for you mapping between objects. Objects are mapped to a model to allow security policy and schema verification.

We have currently File, DynamoDB and MongoDB storage

warning

If you run several instances of your application, you should have a pub/sub to notify the other instances of the changes or disable cache by setting disableCache to true

Configuring Mapping​

As an example we will use the Users / Idents stores used by the Authentication module.

A User has several Idents so in NoSQL we need to deduplicate a part of the Ident object inside an array inside the User object

The following is the Idents store configuration

webda.config.json
{
  ...
  "map": {
     "Users": { // Target store
        "key": "user", // Property inside Ident Object
        "target": "idents", // Property on the User Object
        "fields": "type", // Fields from the Ident Object ( uuid is added by default )
        "cascade": true // If User object is delete then delete all the linked Idents
     }
  }

So if you have a user like

{
  ...
  "uuid": "user_01"
}

Then you save a new Ident object like

{
  ...
  "uuid": "ident_01",
  "user": "user_01",
  "type": "Google"
}

Once the Ident saved, the User object will look like

{
  ...
  "uuid": "user_01",
  "idents": [{"uuid":"ident_01","type":"Google"}]
  ...
}

Then if you update the field type on your Ident object the User object will reflect the change, as well as if you delete the ident object it will be removed from the User object.

If cascade = true, then if you delete the User object, all attached Idents will be delete aswell.

Events​

The Stores emit events to let you implement some auto completion of the object if needed or taking any others action even deny the action by throwing an exception

The store event looks like

{
  'object': object,
  'store': this
}

Store.Save: Before saving the object Store.Saved: After saving the object Store.Update: Before updating the object Store.Updated: After updating the object Store.Delete: Before deleting the object Store.Deleted: After deleting the object Store.Get: When getting the object

DynamoDB configuration​

The DynamoDB stores requires at least accessKeyId, secretAccessKey and table

For more information on DynamoDB : AWS DynamoDB

MongoDB configuration​

The MongoDB configuration requires a collection and a mongo parameter where mongo is the MongoDB url

FileDB configuration​

The FileDB only requires a folder where to store the datas. It creates it if not exists

See also​