loopback-component-jsonapi

jsonapi.org support for loopback.

Status

This project is now pretty stable and is used in production in a number of our projects. There are known issues (see below and the issue tracker) these can mostly be worked around or are pretty minor. Open an issue on the issue tracker if you need clarification on anything or need help.

Known issues

This module doesn't do complex compound documents very well yet. This means that if you try to do complex includes in a single request you will likely run into trouble.

We wrote another module called loopback-jsonapi-model-serializer that does JSONAPI serialization very well (but nothing else) for loopback which you can use to get around such issues for now. The long term goal is to swap out the serialization layer in loopback-component-jsonapi with loopback-jsonapi-model-serializer

Tested against:

• Node 4, 6 and 8
• JSON API v1.0
• loopback ^3.8.0

Sample Project

We have created a sample project using EmberJS, Loopback and this compoment. It's called emberloop.

Helping out

We are VERY interested in help. Get in touch via the issue tracker Please read the following about contributing:

Semantic Release

This project uses Semantic Release to manage the release process. This means that: A. There is no semver project version in package.json. This is managed in CI. B. Commit messages need to follow conventions. See here for commit message guidelines. The important things to remember are: A. If you are fixing a bug prefix your commit message with fix(<thing being fixed goes here>): B. If you are adding a non breaking feature, prefix your commit with feat(<name of feature goes here>): C. If you are making a breaking change of any kind, prefix additional information on the 3rd line of the commit message with: BREAKING CHANGE: See examples of this on the Semantic Release github pages. And don't hesitate to reach out on our issue tracker if you want further clarification.

Standard js and "prettier standard"

This project is follows the Standard js styleguide. Linting happens on CI and any time you run tests via npm test You can run the linting on its own with npm run lint

Additionally, code formatting is done whenever you run git commit. This is made possibly by lint-staged and husky with actual formatting done by prettier

Pull requests and code review

All code is reviewed by one or more of the project maintainers before merging. Before becoming a maintainer, contributers need to fork the master branch of this repo, make their changes and submit a pull request.

Once a contributor becomes a maintainer, it is preferred that they create new branches on the loopback-component-jsonapi repo and submit those as pull requests

Tests

We take testing seriously. The project contains over 200 tests at time of writing this. In most cases we wont merge anything without tests. (Within reason of course)

Project maintainers

We follow the principle of "Open open source" which means if you contribute even a single PR to the project, we make you a project maintainer.

Debugging

You can enable debug logging by setting an environment variable: DEBUG=loopback-component-jsonapi

example:

DEBUG=loopback-component-jsonapi node .

API Documentation

Getting started

In your loopback project:

1. npm install --save loopback-component-jsonapi
2. Create a component-config.json file in your server folder (if you don't already have one)
3. Add the following config to component-config.json

{
  "loopback-component-jsonapi": {}
}

Advanced usage:

We are aiming to make the component as configurable as possible. You can configure how the component behaves with the options shown and listed below. If there is something else you would like to see be configurable, please submit an issue on the repository. For remote methods, root must be set to true.

Example: (all configuration options listed)

{
  "loopback-component-jsonapi": {
    "restApiRoot": "/api",
    "host": "https://www.mydomain.com",
    "enable": true,
    "handleErrors": true,
    "errorStackInResponse": false,
    "handleCustomRemoteMethods": false,
    "exclude": [
      {"model": "comment"},
      {"methods": "find"},
      {"model": "post", "methods": "find"},
      {"model": "person", "methods": ["find", "create"]}
    ],
    "hideIrrelevantMethods": true,
    "attributes": {
      "posts": ["title"]
    },
    "include": [
      {"methods": "customMethod"},
      {"model": "post", "methods": "customMethod"},
      {"model": "person", "methods": ["customMethod1", "customMethod2"]}
    ]
  }
}

restApiRoot

Url prefix to be used in conjunction with host and resource paths. eg. http://127.0.0.1:3214/api/people

example

{
  ...
  "restApiRoot": "/api",
  ...
}

• Type: string
• Default: /api

host

The url of the application, to be used when constructing links to relationships. Useful where the service is proxied and the application believes it is running on a different url to that seen by the consuming service.

example

{
  ...
  "host": "https://www.mydomain.com",
  ...
}

• Type: string
• Default: null

enable

Whether the component should be enabled or disabled. Defaults to true, flip it to false if you need to turn the component off without removing the configuration for some reason.

example

{
  ...
  "enable": true,
  ...
}

• Type: boolean
• Default: true

handleErrors

When true, the component will unregister all other error handling and register a custom error handler which always returns errors in JSON API compliant format. Validation errors include the correct properties in order to work out of the box with EmberJS.

example

{
  ...
  "handleErrors": true,
  ...
}

• Type: boolean
• Default: true

errorStackInResponse

Along handleErrors, When true, this option will send the error stack if available within the error response. It will be stored under the source.stack key.

Please be careful, this option should never be enabled in a production environment. Doing so can expose sensitive data.

example

{
  ...
  "errorStackInResponse": NODE_ENV === 'development',
  ...
}

• Type: boolean
• Default: false

handleCustomRemoteMethods

Allow all (custom) remote methods to be serialized by default.

This option can be overridden in any of the following ways:

1. Setting a jsonapi property to true or false in a remote method definition.
2. Globally adding the remote method to the component's exclude array.
3. Globally adding the remote method to the component's include array.

example

{
  ...
  "handleCustomRemoteMethods": true,
  ...
}

• Type: boolean
• Default: false

exclude

Allows blacklisting of models and methods. Define an array of blacklist objects. Blacklist objects can contain "model" key "methods" key or both. If just "model" is defined then all methods for the specified model will not be serialized of deserialized using JSON API. If just the "methods" key is defined then all methods specified on all models will not be serialized or deserialized using JSON API. If a combination of "model" and "methods" keys are used then the specific combination of model and methods specified will not be serialized or deserialized using JSON API.

example

{
  ...
  "exclude": [
    {"model": "comment"},
    {"methods": "find"},
    {"model": "post", "methods": "find"},
    {"model": "person", "methods": ["find", "create"]}
  ],
  ...
}

• Type: array
• Default: null

Note

The default behavior is to modify (serialize to JSON API) the output of the following CRUD methods on all models:

• find
• create
• updateAttributes
• deleteById
• findById

In addition the following wild card method names are matched and the output is modified in order to handle relationships eg. /api/posts/1/comments

• __get__.*
• __findRelationships__.*

The default behavior is to modify (deserialize from JSON API) the input to the following CRUD methods on all models:

• create
• updateAttributes

include

Allows whitelisting of methods. Define an array of whitelist objects. Whitelist objects can contain a "methods" key or both a "models" key and a "methods" key. If just the "methods" key is defined then the methods specified will be serialized or deserialized using JSON API on all models that have the specified methods. If a combination of "model" and "methods" keys are used then the specific combination of model and methods specified will be serialized or deserialized using JSON API.

Note: objects returned from a remote method that will be JSON API serialized MUST include an id property. id property can be null.

example

{
  ...
  "include": [
    {"methods": "customMethod"},
    {"model": "post", "methods": "customMethod"},
    {"model": "person", "methods": ["customMethod1", "customMethod2"]}
  ],
  ...
}

• Type: array
• Default: null

hideIrrelevantMethods

By default, loopback-component-jsonapi disables a number of methods from each endpoint that are not JSON API relevant. These methods are:

• upsert
• exists
• findOne
• count
• createChangeStream
• updateAll

You can use this option to prevent loopback-component-jsonapi from doing so. These methods are not modified by the component. Their output will not be in a JSON API compliant format.

example

{
  ...
  "hideIrrelevantMethods": true,
  ...
}

• Type: boolean
• Default: true

attributes

By default, model properties will be converted to attributes in JSON API terms. All model properties except the primary key and any foreign keys will be copied into the attributes object before output. If you wish to limit which properties will be output as attributes you can specify a whitelist of attributes for each type.

example

{
  ...
  "attributes": {
    "posts": ["title", "content"],
    "comments": ["createdAt", "updatedAt", "comment"]
  }
  ...
}

• Type: object
• Default: null

note

The attributes arrays are keyed by type not by model name. Type is the term used by JSON API to describe the resource type in question and while not required by JSON API it is usually plural. In loopback-component-jsonapi it is whatever the models plural is set to in model.json. So in our example above we defined: "posts": ["title", "content"] as the resource type for the post model is posts

foreignKeys

Allows configuration of whether the component should expose foreign keys (which the jsonapi spec considers implementation details) from the attributes hash.

examples

Always expose foreign keys for all models

{
  ...
  foreignKeys: true,
  ...
}

Never expose foreign keys for any models (default behaviour)

{
  ...
  foreignKeys: false,
  ...
}

Only expose foreign keys for the comment model

{
  ...
  foreignKeys: [
    {model: 'comment'}
  ],
  ...
}

Only expose foreign keys for the comment model findById method. eg. GET /api/comments/1

{
  ...
  foreignKeys: [
    {model: 'comment', method: 'findById'}
  ],
  ...
}

• Type: boolean|array
• Default: false

Custom remote methods

jsonapi remote method options

Sometimes you need to be able to control when a custom remote method should be handled by the component. By default, loopback-component-jsonapi will not handle (serialize or deserialize) custom remote methods. In order to tell the component to handle a custom remote method, you have the following options (In priority order):

1. Set jsonapi to true when defining a custom remote method.
2. Add the methods name to the component's exclude array setting. (see above)
3. Add the methods name to the component's include array setting. (see above)
4. Set handleCustomRemoteMethods to true in the component's settings. (see above)

This option takes precedence and sets the component to handle or not handle the custom remote method.

examples

Post.remoteMethod('greet', {
  jsonapi: true
  returns: { root: true }
})

Ensures that the response from Post.greet will follow JSONApi format.

Post.remoteMethod('greet', {
  jsonapi: false
  returns: { arg: 'greeting', type: 'string' }
})

Ensures that the response from Post.greet will never follow JSONApi format.

Note

You must always pass root: true to the returns object when using loopback-component-jsonapi. This is especialy important when you expect the response to be an array.

Overriding serialization type

When loopback-component-jsonapi serializes a custom remote method, by default it will assume that the data being serialized is of the same type as the model the custom remote method is being defined on. Eg. For a remote method on a Comment model, it will be assumed that the data being returned from the remote method will be a comment or an array of comments. When this is not the case, you will need to set the type property in the returns object in the remote method definition.

If an unknown type or no type are given, the model name will be used.

example

Post.remoteMethod('prototype.ownComments', {
  jsonapi: true
  returns: { root: true, type: 'comment' }
})

Custom Serialization

For occasions where you need greater control over the serialization process, you can implement a custom serialization function for each model as needed. This function will be used instead of the regular serialization process.

example

module.exports = function (MyModel) {
  MyModel.jsonApiSerialize = function (options, callback) {
    // either return an error
    var err = new Error('Unable to serialize record');
    err.status = 500;
    cb(err)

    // or return serialized records
    if (Array.isArray(options.records)) {
      // serialize an array of records
    } else {
      // serialize a single record
    }
    cb(null, options);
  }
}

function parameters

• options All config options set for the serialization process.
• callback Callback to call with error or serialized records

Custom Deserialization

For occasions where you need greater control over the deserialization process, you can implement a custom deserialization function for each model as needed. This function will be used instead of the regular deserialization process.

example

module.exports = function (MyModel) {
  MyModel.jsonApiDeserialize = function (options, callback) {
    // either return an error
    var err = new Error('Unable to deserialize record');
    err.status = 500;
    cb(err)

    // or
    // options.data is the raw data
    // options.result needs to be populated with deserialization result
    options.result = options.data.data.attributes;

    cb(null, options);
  }
}

Custom Errors

Generic errors respond with a 500, but sometimes you want to have a better control over the error that is returned to the client, taking advantages of fields provided by JSONApi.

It is recommended that you extend the base Error constructor before throwing errors. Eg. BadRequestError

meta and source fields needs to be objects.

example

module.exports = function (MyModel) {
  MyModel.find = function () {
    var err = new Error('April 1st, 1998');
    
    err.status = 418;
    err.name = 'I\'m a teapot';
    err.source = { model: 'Post', method: 'find' };
    err.detail = 'April 1st, 1998';
    err.code = 'i\'m a teapot';
    err.meta = { rfc: 'RFC2324' };

    throw err
  }
}

// This will be returned as :
// {
//   errors: [
//     {
//       status: 418,
//       meta: { rfc: 'RFC2324' },
//       code: 'i\'m a teapot',
//       detail: 'April 1st, 1998',
//       title: 'I\'m a teapot',
//       source: { model: 'Post', method: 'find' }
//     }
//   ]
// }

function parameters

• options All config options set for the deserialization process.
• callback Callback to call with error or serialized records

The options object

options.type

Resource type. Originally calculated from a models plural. Is used in the default serialization process to set the type property for each model in a JSON API response.

• eg. posts

options.method

The method that was called to get the data for the current request. This is not used in the serialization process but is provided for custom hook and serialization context.

• Eg. create, updateAttributes

options.primaryKeyField

The name of the property that is the primary key for the model. This is usually just id unless defined differently in a model.json file.

options.requestedIncludes

The relationships that the user has requested be side loaded with the request. For example, for the request GET /api/posts?include=comments options.requestedIncludes would be 'comments'.

• Type: string or array
• eg: 'comments' or ['posts', 'comments']

options.host

The host part of the url including any port information.

• eg. http://localhost:3000

options.restApiRoot

The api prefix used before resource information. Can be used in conjunction with options.host and options.type to build up the full url for a resource.

• eg. /api

options.topLevelLinks

Links object used at the top level of the JSON API response structure.

• eg. {links: {self: 'http://localhost:3000/api/posts'}}

options.dataLinks

Links object used to generate links for individual resource items. The structure is and object with JSON API link keys such as self or related that are defined as a function that will be called for each resource.

Eg.

options.dataLinks: {
  self: function (resource) {
    return 'http://localhost:3000/posts/' + resource.id;
  }
}

As shown above, each resource gets passed to the function and the result of the function is assigned to the key in the final JSON API response.

options.relationships

This contains all the relationship definitions for the model being serialized. Relationship definition objects are in the same format as in loopback's Model.relations definition. An object with relationship name keys, each having properties:

• modelTo loopback model object
• keyTo name of key on to model
• modelFrom loopback model object
• keyFrom name of key on from model
• type type of relationship (belongsTo, hasOne, hasMany)

This information is used to build relationship urls and even setup side-loaded data correctly during the serialization process.

eg.

options.relationships = {
  comments: { modelTo: ...etc },
  tags: { modelTo: ...etc }
}

options.results

This is the actual data to be serialized. In beforeJsonApiSerialize and jsonApiSerialize this will be the raw data as you would ordinarily get it from loopback. In afterJsonApiSerialize this will be the serialized data ready for any final modifications.

options.exclude

This is the exclude settings as defined in the exclude configuration option explained earlier. Use this in beforeJsonApiSerialize to make any model specific adjustments before serialization.

options.attributes

This is the attributes settings as defined in the attributes configuration option explained earlier. Use this in beforeJsonApiSerialize to make any model specific adjustments before serialization.

options.data

The raw body data prior to deserialization from creates and updates. This can be manipulated prior to deserialization using beforeJsonApiDeserialize

options.result

The deserialized raw body data. This is used when saving models as part of a create or update operation. You can manipulate this prior to the save occuring in afterJsonApiDeserialize

Serialization/Deserialization Hooks

For occasions when you don't want to fully implement (de)serialization for a model manually but you need to manipulate the serialization/deserialization process, you can use the hooks beforeJsonApiSerialize, afterJsonApiSerialize, beforeJsonApiDeserialize and afterJsonApiDeserialize.

beforeJsonApiDeserialize

In order to modify the deserialization process on a model by model basis, you can define a Model.beforeJsonApiDeserialize function as shown below. The function will be called with an options object and a callback which must be called with either an error as the first argument or the modified options object as the second parameter.

Examples of things you might want to use this feature for

• modifying options.data.data.attributes prior to their being deserialized into model properties that will be saved
• modifying options.data.data.relationships prior to their being used to save relationship linkages

code example

module.exports = function (MyModel) {
  MyModel.beforeJsonApiDeserialize = function (options, callback) {
    // either return an error
    var err = new Error('Unwilling to deserialize record');
    err.status = 500;
    callback(err)

    // or return modified data
    options.data.data.attributes.title = 'modified title';

    // returned options.data will be deserialized by either the default deserialization process
    // or by a custom deserialize function if one is present on the model.
    callback(null, options);
  }
}

afterJsonApiDeserialize

This function will be called with an options object and a callback which must be called with either an error as the first argument or the modified options object as the second parameter.

Examples of things you might want to use this feature for

• modifying options.result after their having being deserialized from options.data.data.attributes
• modifying options.data.data.relationships prior to their being used to save relationship linkages

code example

module.exports = function (MyModel) {
  MyModel.afterJsonApiDeserialize = function (options, callback) {
    // either return an error
    var err = new Error('something went wrong!');
    err.status = 500;
    callback(err)

    // or return modified data prior to model being saved with options.result
    options.result.title = 'modified title';

    callback(null, options);
  }
}

function parameters

• options All config options set for the deserialization process. See the "the options object" section above for info on what options properties are available for modification.
• callback Callback to call with error or options object.

beforeJsonApiSerialize

In order to modify the serialization process on a model by model basis, you can define a Model.beforeJsonApiSerialize function as shown below. The function will be called with an options object and a callback which must be called with either an error as the first argument or the modified options object as the second parameter.

Examples of things you might want to use this feature for

• modify the record(s) before serialization by modifying options.results
• modify the resource type by modifying options.type
• setup serialization differently depending on options.method
• side load data (advanced)
• modify the way relationships are serialized

code example

module.exports = function (MyModel) {
  MyModel.beforeJsonApiSerialize = function (options, callback) {
    // either return an error
    var err = new Error('Unable to serialize record');
    err.status = 500;
    callback(err)

    // or return modified records
    if (Array.isArray(options.results)) {
      // modify an array of records
    } else {
      // modify a single record
    }
    // returned options.records will be serialized by either the default serialization process
    // or by a custom serialize function (described above) if one is present on the model.
    callback(null, options);
  }
}

function parameters

• options All config options set for the serialization process. See the "function parameters" section above for info on what options properties are available for modification.
• callback Callback to call with error or options object.

example use case

Because the beforeJsonApiSerialize method is passed all the options that will be used during serialization, it is possible to tweak options to affect the serialization process. One example of this is modifying the type option to change the resource type that will be output.

module.exports = function (MyModel) {
  MyModel.beforeJsonApiSerialize = function (options, callback) {
    options.type = 'mycustommodels';
    cb(null, options);
  }
}

afterJsonApiSerialize

In order to modify the serialized data on a model by model basis, you can define a Model.afterJsonApiSerialize function as shown below. The function will be called with an options object and a callback which must be called with either an error as the first argument or the modified options object as the second parameter.

example

module.exports = function (MyModel) {
  MyModel.afterJsonApiSerialize = function (options, callback) {
    // either return an error
    var err = new Error('Unable to modify serialized record');
    err.status = 500;
    callback(err)

    // or return modified records
    if (Array.isArray(options.results)) {
      // modify an array of serialized records
    } else {
      // modify a single serialized record
    }
    // returned options.records will be output through the api.
    callback(null, options);
  }
}

function parameters

• options All config options set for the serialization process
• callback Callback to call with modified serialized records