Recommendations

This section contains recommendations for JSON:API implementations. These recommendations are intended to establish a level of consistency in areas that are beyond the scope of the base JSON:API specification.

Naming

The specification places certain hard restrictions on how members (i.e., keys) in a JSON:API document may be named. To further standardize member names, which is especially important when mixing profiles authored by different parties, the following rules are also recommended:

• Member names SHOULD be camel-cased (i.e., wordWordWord)
• Member names SHOULD start and end with a character “a-z” (U+0061 to U+007A)
• Member names SHOULD contain only ASCII alphanumeric characters (i.e., “a-z”, “A-Z”, and “0-9”)

URL Design

Reference Document

When determining an API’s URL structure, it is helpful to consider that all of its resources exist in a single “reference document” in which each resource is addressable at a unique path. Resources are grouped by type at the top level of this document. Individual resources are keyed by ID within these typed collections. Attributes and links within individual resources are uniquely addressable according to the resource object structure described above.

This concept of a reference document is used to determine appropriate URLs for resources as well as their relationships. It is important to understand that this reference document differs slightly in structure from documents used to transport resources due to different goals and constraints. For instance, collections in the reference document are represented as sets because members must be addressable by ID, while collections are represented as arrays in transport documents because order is significant.

URLs for Resource Collections

It is recommended that the URL for a collection of resources be formed from the resource type.

For example, a collection of resources of type photos will have the URL:

/photos

URLs for Individual Resources

Treat collections of resources as sets keyed by resource ID. The URL for an individual resource can be formed by appending the resource’s ID to the collection URL.

For example, a photo with an ID of "1" will have the URL:

/photos/1

Relationship URLs and Related Resource URLs

As described in the base specification, there are two URLs that can be exposed for each relationship:

• the “relationship URL” - a URL for the relationship itself, which is identified with the self key in a relationship’s links object. This URL allows the client to directly manipulate the relationship. For example, it would allow a client to remove an author from a post without deleting the people resource itself.

• the “related resource URL” - a URL for the related resource(s), which is identified with the related key within a relationship’s links object. When fetched, it returns the related resource object(s) as the response’s primary data.

It is recommended that a relationship URL be formed by appending /relationships/ and the name of the relationship to the resource’s URL.

For example, a photo’s comments relationship will have the URL:

/photos/1/relationships/comments

And a photo’s photographer relationship will have the URL:

/photos/1/relationships/photographer

It is recommended that a related resource URL be formed by appending the name of the relationship to the resource’s URL.

For example, the URL for a photo’s comments will be:

/photos/1/comments

And the URL for a photo’s photographer will be:

/photos/1/photographer

Because these URLs represent resources in relationships, they should not be used as self links for the resources themselves. Instead the recommendations for individual resource URLs should still apply when forming self links.

Filtering

The base specification is agnostic about filtering strategies supported by a server. The filter query parameter family is reserved to be used as the basis for any filtering strategy.

It’s recommended that servers that wish to support filtering of a resource collection based upon associations do so by allowing query parameters that combine filter with the association name.

For example, the following is a request for all comments associated with a particular post:

GET /comments?filter[post]=1 HTTP/1.1

Multiple filter values can be combined in a comma-separated list. For example:

GET /comments?filter[post]=1,2 HTTP/1.1

Furthermore, multiple filters can be applied to a single request:

GET /comments?filter[post]=1,2&filter[author]=12 HTTP/1.1

Including Top-level, Resource-level and Relationship Links

The base specification is agnostic about including links with a resource response. However, it is recommended that the following links be included within response documents:

• Top-level links like a self-link (for the whole response) as well as relative pagination links (if appropriate).
• Resource-level links like a self-link for each resource (which differs from the top-level, if the resource is part of a collection).
• Relationship links for all available relationships of a resource.

For example, a request for a collection of comments could prompt the following response:

GET /comments HTTP/1.1

{
  "data": [{
      "type": "comments",
      "id": "1",
      "attributes": {
          "text": "HATEOS are the thing!"
      },
      "links": {
          "self": "/comments/1"
      },
      "relationships": {
        "author": {
          "links": {
            "self": "/comments/1/relationships/author",
            "related": "/comments/1/author"
          }
        },
        "articles": {
          "links": {
            "self": "/comments/1/relationships/articles",
            "related": "/comments/1/articles"
          }
        }
      }
  }],
  "links": {
      "self": "/comments"
  }
}

Supporting Clients Lacking PATCH

Some clients, like IE8, lack support for HTTP’s PATCH method. API servers that wish to support these clients are recommended to treat POST requests as PATCH requests if the client includes the X-HTTP-Method-Override: PATCH header. This allows clients that lack PATCH support to have their update requests honored, simply by adding the header.

Formatting Date and Time Fields

Although JSON:API does not specify the format of date and time fields, it is recommended that servers align with ISO 8601. This W3C NOTE provides an overview of the recommended formats.

Asynchronous Processing

Consider a situation when you need to create a resource and the operation takes a long time to complete.

POST /photos HTTP/1.1

The request SHOULD return a status 202 Accepted with a link in the Content-Location header.

HTTP/1.1 202 Accepted
Content-Type: application/vnd.api+json
Content-Location: https://example.com/photos/jobs/5234

{
  "data": {
    "type": "jobs",
    "id": "5234",
    "attributes": {
      "status": "Pending request, waiting other process"
    },
    "links": {
      "self": "/photos/jobs/5234"
    }
  }
}

To check the status of the job process, a client can send a request to the location given earlier.

GET /photos/jobs/5234 HTTP/1.1
Accept: application/vnd.api+json

Requests for still-pending jobs SHOULD return a status 200 OK, as the server is reporting the status successfully. Optionally, the server can return a Retry-After header to provide guidance to the client as to how long it should wait before checking again. Recommendations to retry sooner than 1 second can be accomplised with Retry-After: 0.

HTTP/1.1 200 OK
Content-Type: application/vnd.api+json
Retry-After: 10

{
  "data": {
    "type": "jobs",
    "id": "5234",
    "attributes": {
      "status": "Pending request, waiting other process"
    },
    "links": {
      "self": "/photos/jobs/5234"
    }
  }
}

When job process is done, the request SHOULD return a status 303 See other with a link in Location header.

HTTP/1.1 303 See other
Content-Type: application/vnd.api+json
Location: https://example.com/photos/4577

Authoring Profiles

Profiles are a mechanism that can be used by the sender of a document to make promises about its content, without adding to or altering the basic semantics of the JSON:API specification. For example, a profile may indicate that all resource objects will have a timestamps attribute field and that the members of the timestamps object will be formatted using the ISO 8601 date time format.

A profile is an independent specification of those promises. The following example illustrates how the aforementioned profile might be authored:

# Timestamps profile

## Introduction

This page specifies a profile for the `application/vnd.api+json` media type,
as described in the [JSON:API specification](http://jsonapi.org/format/).

This profile allows every resource in a JSON:API document to represent
significant timestamps in a consistent way.

## Document Structure

Every resource object **MUST** include a `timestamps` member in its associated
`attributes` object. If this member is present, its value **MUST** be an object that
**MAY** contain at least one of the following members:

* `created`
* `updated`

The value of each member **MUST** comply with the variant of ISO 8601 used by
JavaScript's `JSON.stringify` method to format Javascript `Date` objects.