loopback-example-relations

$ git clone https://github.com/strongloop/loopback-example-relations.git
$ cd loopback-example-model-relations
$ npm install
$ node .

In this example, we create a simple web app to demonstrate basic model relation concepts. The app consists of a single web page with a list of links to help us query and filter sample data via REST.

Prerequisites

Tutorials

Knowledge

Procedure

Create the application

Application information

Name: loopback-example-model-relations
Directory to contain the project: loopback-example-model-relations

$ slc loopback loopback-example-model-relations
... # follow the prompts
$ cd loopback-example-model-relations

Create the models

Model information

Name: Customer
- Data source: db (memory)
- Base class: PersistedModel
- Expose over REST: Yes
- Custom plural form: Leave blank
- Properties:
  - name
    - String
    - Not Required
  - age
    - String
    - Not Required
Name: Review
- Data source: db (memory)
- Base class: PersistedModel
- Expose over REST: Yes
- Custom plural form: Leave blank
- Properties:
  - product
    - String
    - Not Required
  - star
    - Number
    - Not Required
Name: Order
- Data source: db (memory)
- Base class: PersistedModel
- Expose over REST: Yes
- Custom plural form: Leave blank
- Properties:
  - description
    - String
    - Not Required
  - total
    - Number
    - Not Required

$ slc loopback:model Customer
... # follow the prompts, repeat for `Review` and `Order` models

Configure server-side views

LoopBack comes preconfigured with EJS out-of-box. This means we can use server-side templating by simply setting the proper view engine and a directory to store the views.

Create a views directory to store server-side templates.

$ mkdir server/views

Add server-side templating configurations to server.js.

Create index.ejs in the views directory.

Configure server.js to use server-side templating. Remember to import the path package.

Add sample data

Create three boot scripts:

Create model relations

Model relation information

Customer
- has many
  - Review
    - Property name for the relation: reviews
    - Custom foreign key: authorId
  - Order
    - Property name for the relation: orders
    - Custom foreign key: customerId
    - Require a through model: No
Review
- belongs to
  - Customer
    - Property name for the relation: author
    - Custom foreign key: authorId
Order
- belongs to
  - Customer
    - Property name for the relation: Leave blank - defaults to customer
    - Custom foreign key: Leave blank

$ slc loopback:relation
? Select the model to create the relationship from:
...
> Customer
... # follow the prompts, repeat for `Review` and `Order`

LoopBack automatically derives relation and foreign key names when you leave the values empty.

Try the API

Start the application with node . and browse to localhost:3000. You should see various links. Each endpoint is defined as follows:

/api/customers
- List all customers
/api/customers?filter[fields][0]=name
- List all customers, but only return the name property for each result
/api/customers/1
- Look up a customer by ID
/api/customers/youngFolks
- List a predefined scope named youngFolks
/api/customers/1/reviews
- List all reviews posted by a given customer
/api/customers/1/orders
- List all orders placed by a given customer
/api/customers?filter[include]=reviews
- List all customers including their reviews
/api/customers?filter[include][reviews]=author
- List all customers including their reviews which also include the author
/api/customers?filter[include][reviews]=author&filter[where][age]=21
- List all customers whose age is 21, including their reviews which also include the author
/api/customers?filter[include][reviews]=author&filter[limit]=2
- List first two customers including their reviews which also include the author
/api/customers?filter[include]=reviews&filter[include]=orders
- List all customers including their reviews and orders

EnergisaOne / loopback-example-relations