Connecting models to data sources

</figure>  

LoopBack models connect to backend systems such as databases via data sources that provide create, retrieve, update, and delete (CRUD) functions. LoopBack also generalizes other backend services, such as REST APIs, SOAP web services, and storage services, and so on, as data sources.

Data sources are backed by connectors that implement the data exchange logic using database drivers or other client APIs. In general, applications don’t use connectors directly, rather they go through data sources using the DataSource  and  PersistedModel APIs.

Basic procedure

To connect a model to a data source, follow these steps:

1. Use the  data source generator  to create a new data source.

   For example: 

   $ apic create --type datasource
   ? Enter the data-source name: mysql-corp
   ? Select the connector for mysql: MySQL (supported by StrongLoop)
   

   $ slc loopback:datasource
   ? Enter the data-source name: mysql-corp
   ? Select the connector for mysql: MySQL (supported by StrongLoop)
   

   Follow the prompts to name the datasource and select the connector to use. This adds the new data source to datasources.json.

2. Edit server/datasources.json to add the necessary authentication credentials: typically hostname, username, password, and database name.

   For example:

   server/datasources.json

   "mysql-corp": {
     "name": "mysql-corp",
     "connector": "mysql",
     "host": "your-mysql-server.foo.com",
     "user": "db-username",
     "password": "db-password",
     "database": "your-db-name"
   }
   

   For information on the properties that each connector supports, see documentation for the specific connector under Connectors reference.

3. Install the corresponding connector as a dependency of your app with npm.

   For example: 

   $ cd <your-app>
   $ npm install --save loopback-connector-mysql
   

   See Connectors reference. for the list of connectors.

4. Use the model generator to create a model.

   $ apic create --type model
   ? Enter the model name: myModel
   ? Select the data-source to attach myModel to: mysql (mysql)
   ? Select model's base class: PersistedModel
   ? Expose myModel via the REST API? Yes
   ? Custom plural form (used to build REST URL):
   Let's add some test2 properties now.
   ...
   

   $ slc loopback:model
   ? Enter the model name: myModel
   ? Select the data-source to attach myModel to: mysql (mysql)
   ? Select model's base class: PersistedModel
   ? Expose myModel via the REST API? Yes
   ? Custom plural form (used to build REST URL):
   Let's add some test2 properties now.
   ...
   

   When prompted for the data source to attach to, select the one you just created. 

You can also create models from an existing database; see Creating models for more information.

Connectors

The following table lists commercially-supported LoopBack connectors. For more information, see Database connectors and Non-database connectors.

Installing a connector

Run npm install --save <_connector-module_> in your application root directory to add the dependency to package.json; for example, to install the Oracle database connector:

$ cd <your-app>
$ npm install --save loopback-connector-oracle

This command adds the following entry to package.json: 

...
"dependencies": {
  "loopback-connector-oracle": "latest"
}
...

Creating a data source

Use the data source generator to create a new data source:

$ apic create --type datasource

$ slc loopback:datasource

Follow the prompts to add the desired data source.

You can also create a data source programmatically; see Advanced topics: data sources for more information.

Data source properties

Data source properties depend on the specific data source being used. However, data sources for database connectors (Oracle, MySQL, PostgreSQL, MongoDB, and so on) share a common set of properties, as described in the following table.