https://github.com/strongloop/loopback-example-relations

Basic model relations concepts.
https://github.com/strongloop/loopback-example-relations

Last synced: 10 months ago
JSON representation

Basic model relations concepts.

• Host: GitHub
• URL: https://github.com/strongloop/loopback-example-relations
• Owner: strongloop
• License: other
• Archived: true
• Created: 2015-01-09T21:22:24.000Z (about 11 years ago)
• Default Branch: master
• Last Pushed: 2020-03-05T14:58:16.000Z (almost 6 years ago)
• Last Synced: 2024-11-06T12:59:59.042Z (about 1 year ago)
• Language: JavaScript
• Homepage: https://loopback.io/doc/en/lb2/Creating-model-relations.html
• Size: 112 KB
• Stars: 80
• Watchers: 32
• Forks: 54
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • License: LICENSE
  • Codeowners: CODEOWNERS

Awesome Lists containing this project

README

          
# loopback-example-relations

**⚠️ This LoopBack 3 example project is no longer maintained. Please refer to [LoopBack 4 Examples](https://loopback.io/doc/en/lb4/Examples.html) instead. ⚠️**

```

$ git clone https://github.com/strongloop/loopback-example-relations.git

$ cd loopback-example-relations

$ npm install

$ node .

```

In this example, we create a simple web app to demonstrate 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

Before starting this tutorial, you must install:

- Node.js

- LoopBack CLI tools; see [lb](http://loopback.io/doc/en/lb3/Installation.html)

### Tutorials

- [Getting started with LoopBack](https://github.com/strongloop/loopback-getting-started)

- [Tutorial series - Step 1](https://github.com/strongloop/loopback-getting-started/tree/step1)

### Knowledge

- [LoopBack boot scripts](http://docs.strongloop.com/display/LB/Defining+boot+scripts)

- [LoopBack models](http://docs.strongloop.com/display/LB/Defining+models)

- [Loopback model relations](http://docs.strongloop.com/display/LB/Define+model+relations)

- [Creating loopback model relations](https://docs.strongloop.com/display/public/LB/Creating+model+relations)

## Procedure

### Create the application

#### Application information

- Name: `loopback-example-relations`

- Directory to contain the project: `loopback-example-relations`

```

$ lb app loopback-example-relations

... # follow the prompts

$ cd loopback-example-relations

```

### Create the datasource

- Name: `transient`

- Connector: `other`

  - Name: `transient`

```

$ lb datasource

... # follow the prompts, choose `other` to define custom connector

```

### 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`

      - 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

    - `date`

      - date

      - Not Required

- Name: `Account`

  - Data source: `db (memory)`

  - Base class: `PersistedModel`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `name`

      - String

      - Not Required

    - `date`

      - date

      - Not Required

- Name: `Address`

  - Data source: `transient`

  - Base class: `Model`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `street`

      - String

      - Not Required

    - `city`

      - String

      - Not Required

    - `state`

      - String

      - Not Required

    - `zipCode`

      - String

      - Not Required

- Name: `Author`

  - Data source: `db (memory)`

  - Base class: `PersistedModel`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `name`

      - String

      - Not Required

- Name: `Book`

  - Data source: `db (memory)`

  - Base class: `PersistedModel`

  - Expose over REST: `Yes`

  - Custom plural form: *Leave blank*

  - Properties:

    - `name`

      - String

      - Not Required

- Name: `EmailAddress`

  - Data source: `transient`

  - Base class: `PersistedModel`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `label`

      - String

      - Not Required

    - `address`

      - String

      - Not Required

- Name: `Link`

  - Data source: `transient`

  - Base class: `Model`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `id`

      - number

      - Required

      > Please set `"id": true` manually for this property, like [link.json](/common/models/link.json#L8)

    - `name`

      - String

      - Not Required

    - `notes`

      - String

      - Not Required

- Name: `Reader`

  - Data source: `db (memory)`

  - Base class: `PersistedModel`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `name`

      - String

      - Not Required

- Name: `Shipment`

  - Data source: `db (memory)`

  - Base class: `PersistedModel`

  - Expose over REST: `No`

  - Custom plural form: *Leave blank*

  - Properties:

    - `date`

      - Date

      - Not Required

    - `description`

      - String

      - Not Required

```

$ lb model Customer

... # follow the prompts, repeat for other models

```

> Upper-case in model's name would be interpreted as '-' in model's file name, eg: EmailAddress has `email-address.json`

### 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](https://github.com/strongloop/loopback-example-relations/blob/master/server/views) to store server-side templates.

```

$ mkdir server/views

```

Create [`index.ejs` in the views directory](https://github.com/strongloop/loopback-example-relations/blob/master/server/views/index.ejs).

Create [`account.ejs` in the views directory](https://github.com/strongloop/loopback-example-relations/blob/master/server/views/account.ejs).

Create [`email.ejs` in the views directory](https://github.com/strongloop/loopback-example-relations/blob/master/server/views/email.ejs).

Create [`address.ejs` in the views directory](https://github.com/strongloop/loopback-example-relations/blob/master/server/views/address.ejs).

[Configure `server.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/server.js#L5-L11) to use server-side

templating. Remember to import the [`path`](https://github.com/strongloop/loopback-example-relations/blob/master/server/server.js#L3) package.

### Replace root

Replace the default `root.js` with [a new one](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/root.js) which passes a given customer's id to template engine.

### Add sample data

Create six boot scripts:

- [`sample-customers.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/sample-customers.js)

- [`z-book-people.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/z-book-people.js)

- [`z-customer-accounts.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/z-customer-accounts.js)

- [`z-customer-address.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/z-customer-address.js)

- [`z-customer-emails.js`](https://github.com/strongloop/loopback-example-relations/blob/master/server/boot/z-customer-emails.js)

> We add z- in front of the boot script names to make sure they load last since LoopBack boot loads boot scripts alphabetically.

### Create model relations

#### Model relation information

- `Customer`

  - has many

    - `Order`

      - Property name for the relation: `orders`

      - Custom foreign key: `customerId`

      - Require a through model: No

    - `Other Relations: `(please add them manually)

      ```

      "address": {

        "type": "embedsOne",

        "model": "Address",

        "property": "billingAddress",

        "options": {

          "validate": true,

          "forceId": false

        }

      },

      "emails": {

        "type": "embedsMany",

        "model": "EmailAddress",

        "property": "emailList",

        "options": {

          "validate": true,

          "forceId": false

        }

      },

      "accounts": {

        "type": "referencesMany",

        "model": "Account",

        "property": "accountIds",

        "options": {

          "validate": true,

          "forceId": false

        }

      },

      ```

- `Book`(please add them manually)

  ```

  "people": {

      "type": "embedsMany",

      "model": "Link",

      "scope": {

        "include": "linked"

      }

  }

  ```

- `Link`(please add them manually)

  ```

  "linked": {

    "type": "belongsTo",

    "polymorphic": {

      "idType": "number"

    },

    "properties": {

      "name": "name"

    },

    "options": {

      "invertProperties": true

    }

  }

  ```

- `Order`

  - belongs to

    - `Customer`

      - Property name for the relation: *Leave blank - defaults to `customer`*

      - Custom foreign key: *Leave blank*

  - has many

      - `Shipment`

        - Property name for the relation: *Leave blank - defaults to `shipments`*

        - Custom foreign key: *Leave blank*

- `Shipment`

  - belongs to

    - `Order`

      - Property name for the relation: *Leave blank - defaults to `order`*

      - Custom foreign key: *Leave blank*

```

$ lb relation

? Select the model to create the relationship from:

...

> Customer

... # follow the prompts, repeat for other models

```

> Some relations are not available in `lb`, please add them in `model-name.json` manually.

> LoopBack [automatically derives](http://docs.strongloop.com/display/LB/BelongsTo+relations#BelongsTorelations-Overview)

> relation and foreign key names when you leave the values empty.

### Try the API

Start the application with `node .` and browse to [`localhost:3000`][localhost].

You should see various links. Each endpoint is defined as follows:

#### hasMany

- [/api/customers](http://localhost:3000/api/customers)

  - List all customers

- [/api/customers/4](http://localhost:3000/api/customers/4)

  - Look up a customer by ID

- [/api/customers/youngFolks](http://localhost:3000/api/customers/youngFolks)

  - List a predefined scope named *youngFolks*

- [/api/customers/4/orders](http://localhost:3000/api/customers/4/orders)

  - List a given customer's orders

- [/api/customers?filter[include]=orders](http://localhost:3000/api/customers?filter[include]=orders)

  - List all customers including their orders

- [/api/customers?filter[include][orders]=customer](http://localhost:3000/api/customers?filter[include][orders]=customer)

  - List all customers including their orders which also include the customer

- [/api/customers?filter[include][orders]=customer&filter[where][age]=21](http://localhost:3000/api/customers?filter[include][orders]=customer&filter[where][age]=21)

  - List all customers whose age is 21, including their orders

- [/api/customers?filter[include][orders]=customer&filter[limit]=2](http://localhost:3000/api/customers?filter[include][orders]=customer&filter[limit]=2)

  - List first two customers including their orders

- [/api/customers?filter[include]=accounts&filter[include]=orders](http://localhost:3000/api/customers?filter[include]=accounts&filter[include]=orders)

  - List all customers including their accounts and orders

#### embedsOne

- [/api/customers/2/address](http://localhost:3000/api/customers/2/address)

  - List a given customer's address

#### embedsMany

- [/api/customers/3/emails](http://localhost:3000/api/customers/3/emails)

  - List a given customer's email

#### referencesMany

- [api/customers/1/accounts](http://localhost:3000/api/customers/1/accounts)

  - List all accounts owned by a given customer

- [/api/customers/1/accounts/1](http://localhost:3000/api/customers/1/accounts/1)

  - Look up a given accounts of a given customer by foreign key

- [/api/customers/1/accounts/count](http://localhost:3000/api/customers/1/accounts/count)

  - Count accounts number of a given customer

#### polymorphic embedsMany

- [/api/Books/1/people](http://localhost:3000/api/Books/1/people)

  - List the linked people of a given book

- [/api/Books/1/people/1](http://localhost:3000/api/Books/1/people/1)

  - Look up the author of a given book by foreign key

- [/api/Books/1/people/2](http://localhost:3000/api/Books/1/people/2)

  - Look up the reader of a given book by foreign key

---

[More LoopBack examples](https://loopback.io/doc/en/lb3/Tutorials-and-examples.html)