loopback-jsonapi-model-serializer

JSONAPI Model serializer for loopback

About

The goal of this project is to provide a simple JSONAPI serialization tool for loopback models. You should be able to use (for example) loopbacks PersistedModel.find() method with all its various filter options and pass the returned data (along with the model) into the serializer and have all the intricacies of the JSON APi serialization process taken care of for you. See the example section below.

Installation

npm install loopback-jsonapi-model-serializer --save

Basic Usage

Include the module as a dependency

const serialize = require('loopback-jsonapi-model-serializer')

Use it to serialize a data payload

const serializedData = serialize(data, model)

You will almost certainly want to override baseUrl so that the serializer can prepend urls as neeeded.

const serializedData = serialize(data, model, {baseUrl: 'http://myapi.com/api/'})

API

serialize(data, model, [options])

• data a payload of data from a loopback find, findOne, findById etc.
• model a loopback model eg. app.models.User
• options used to override baseUrl used in serialization process {baseUrl: 'http://localhost:3000/'}

Example

Given the following loopback models and relationships:

const Post = ds.createModel('post', {title: String})
const Comment = ds.createModel('comment', {title: String})
const Author = ds.createModel('author', {name: String})

app.model(Post)
app.model(Author)
app.model(Comment)

Post.hasMany(Comment)
Post.belongsTo(Author)

We can perform the folliowing query:

Post.find().then(data => {...})

Then we serialize the returned data like so:

const serializedData = serialize(data, Post)

After which serializedData should look something like:

{
  "data": [
    {
      "id": 1,
      "type": "posts",
      "links": {
        "self": "/posts/1"
      },
      "attributes": {
        "title": "post 0"
      },
      "relationships": {
        "comments": {
          "links": {
            "related": "/posts/1/comments"
          }
        },
        "author": {
          "links": {
            "related": "/posts/1/author"
          }
        }
      }
    }
  ]
}

Loopback relations

Without fetching included models

When you give the serializer data that does not have any included relationships, The serializer will construct urls that allow consuming clients to fetch related data with an additional query.

In our example above, Post has Many Comment and belongsTo Author. The serializer will construct the following:

"relationships": {
  "comments": {
    "links": {
      "related": "/posts/1/comments"
    }
  },
  "author": {
    "links": {
      "related": "/posts/1/author"
    }
  }
}

Clients can then use these urls to fetch related data as per the JSONAPI spec

Fetching included models

You can use loopbacks include syntax to fetch related data in a single request. These 'side loaded' relations will be handled according to the JSONAPI spec, serialized, placed in the included block and linked to via the relationships data object.

Fetching in loopback with relations

Post.find({include: ['author', 'comments']}).then(data => {
  const serialized = serialize(data, Post)
})

Linking in the relationships data object

When relationship data is included, id and type linkages are made in the relationships object under the appropriate relationships

"relationships": {
  "comments": {
    "links": {
      "related": "/posts/1/comments"
    },
    "data": [
      {"id": 1, "type": "comments"},
      {"id": 2, "type": "comments"}
    ]
  },
  "author": {
    "links": {
      "related": "/posts/1/author"
    },
    "data": {"id": 1, "type": "authors"}
  }
}

Linked resources included in the included array

When relationship data is included, related authors and comments will be serialized and placed in an array under the key included. See the JSONAPI spec for more information.

{
  "data": [...],
  "included": [
    {"id": 1, "type": "comments", "attributes": {}, etc},
    {"id": 1, "type": "authors", "attributes": {}, etc},
    etc.
  ]
}

Other information

You can also make good sense of the serialization process by reading through the tests.