JSONAPI Elixir
A project that will render your data models into JSONAPI Documents and parse/verify JSONAPI query strings.
JSONAPI Support
This library implements version 1.1 of the JSON:API spec.
- Basic JSONAPI Document encoding
- Basic support for compound documents
- Links
- Relationship links
- Parsing of
sort
query parameter into Ecto Query order_by - Parsing and limiting of
filter
keywords. - Handling of sparse fieldsets
- Handling of includes
- Handling of pagination
- Handling of top level meta data
Documentation
Badges
How to use with Phoenix
Installation
Add the following line to your mix.deps
file with the desired version to install jsonapi
.
defp deps do [
...
{:jsonapi, "~> x.x.x"}
...
]
Usage
Simply add use JSONAPI.View
either to the top of your view, or to the web.ex view section and add the
proper functions to your view like so.
defmodule MyApp.PostView do
use JSONAPI.View, type: "posts"
def fields do
[:text, :body, :excerpt]
end
def excerpt(post, _conn) do
String.slice(post.body, 0..5)
end
def meta(data, _conn) do
# this will add meta to each record
# To add meta as a top level property, pass as argument to render function (shown below)
%{meta_text: "meta_#{data[:text]}"}
end
def relationships do
# The post's author will be included by default
[author: {MyApp.UserView, :include},
comments: MyApp.CommentView]
end
end
You can now call render(conn, MyApp.PostView, "show.json", %{data: my_data, meta: meta})
or "index.json"
normally.
If you'd like to use this without Phoenix simply use the JSONAPI.View
and call
JSONAPI.Serializer.serialize(MyApp.PostView, data, conn, meta)
.
Renaming relationships
If a relationship has a different name in the backend than you would like it to in your API,
you can rewrite its name in the JSONAPI.View
. You pair the view with the name of the relationship
used in the data (e.g. Ecto schema) to achieve this. Note that you can use a triple instead
of a pair to add the instruction to always include the relation if desired.
defmodule MyApp.PostView do
use JSONAPI.View, type: "posts"
def relationships do
# The `author` will be exposed as `creator` and the `comments` will be
# exposed as `critiques` (for some reason).
[creator: {:author, MyApp.UserView, :include},
critiques: {:comments, MyApp.CommentView}]
end
end
Parsing and validating a JSONAPI Request
In your controller you may add
plug JSONAPI.QueryParser,
filter: ~w(name),
sort: ~w(name title inserted_at),
view: PostView
This will add a JSONAPI.Config
struct called jsonapi_query
to your
conn.assigns
. If a user tries to sort, filter, include, or requests an
invalid fieldset it will raise a Plug
error that shows the proper error
message.
The config holds the values parsed into things that are easy to pass into an Ecto
query, for example sort=-name
will be parsed into sort: [desc: :name]
which
can be passed directly to the order_by
in Ecto.
This sort of behavior is consistent for includes.
The JSONAPI.QueryParser
plug also supports sparse fieldsets.
Please see its documentation for details.
Camelized or Dasherized Fields
JSONAPI has recommended in the past the use of dashes (-
) in place of underscore (_
) as a
word separator for document member keys. However, as of JSON API Spec (v1.1), it is now recommended that member names
are camelCased. This library provides various configuration options for maximum flexibility including serializing outgoing parameters and deserializing incoming parameters.
Transforming fields requires two steps:
-
camelCase outgoing fields requires you to set the
:field_transformation
configuration option. Example:config :jsonapi, field_transformation: :camelize # or dasherize
-
Underscoring incoming params (both query and body) requires you add the
JSONAPI.UnderscoreParameters
Plug to your API's pipeline. This makes it easy to work with changeset data.pipeline :api do plug JSONAPI.EnsureSpec plug JSONAPI.UnderscoreParameters end
-
JSONAPI.Deserializer is a plug designed to make a JSON:API resource object more convenient to work with when creating or updating resources. This plug works by taking the resource object format and flattening it into an easier to manipulate Map.
Note that the deserializer expects the same casing for your outgoing params as your incoming params.
Your pipeline in a Phoenix app might look something like this:
pipeline :api do plug JSONAPI.EnsureSpec plug JSONAPI.Deserializer plug JSONAPI.UnderscoreParameters end
Spec Enforcement
We include a set of Plugs to make enforcing the JSONAPI spec for requests easy. To add spec enforcement to your application, add JSONAPI.EnsureSpec
to your pipeline:
plug JSONAPI.EnsureSpec
Under-the-hood JSONAPI.EnsureSpec
relies on four individual plugs:
-
JSONAPI.ContentTypeNegotiation
β Requires theContent-Type
andAccept
headers are set correctly. -
JSONAPI.FormatRequired
β Verifies that the JSON body matches the expected%{data: %{attributes: attributes}}
format. -
JSONAPI.IdRequired
β Confirm theid
key is present in%{data: data}
and that it matches the resource'sid
in the URI. -
JSONAPI.ResponseContentType
β Ensures that you return the correctContent-Type
header.
Configuration
config :jsonapi,
host: "www.someotherhost.com",
scheme: "https",
namespace: "/api",
field_transformation: :underscore,
remove_links: false,
json_library: Jason,
paginator: nil
- host, scheme. By default these are pulled from the
conn
, but may be overridden. - namespace. This optional setting can be used to configure the namespace
your resources live at (e.g. given "http://example.com/api/cars",
"/api"
would be the namespace). See alsoJSONAPI.View
for setting on the resource's View itself. - field_transformation. This option describes how your API's fields word
boundaries are marked. JSON API Spec (v1.1) recommends using camelCase (e.g.
"favoriteColor": blue
). If your API uses camelCase fields, set this value to:camelize
. JSON:API v1.0 recommended using a dash (e.g."favorite-color": blue
). If your API uses dashed fields, set this value to:dasherize
. If your API uses underscores (e.g."favorite_color": "red"
) set to:underscore
. - remove_links.
links
data can optionally be removed from the payload via setting the configuration above totrue
. Defaults tofalse
. - json_library. Defaults to Jason.
- paginator. Module implementing pagination links generation. Defaults to
nil
.
Pagination
Pagination links can be generated by overriding the JSONAPI.View.pagination_links/4
callback of your view and returning a map containing the links.
...
def pagination_links(data, conn, page, options) do
%{first: nil, last: nil, prev: nil, next: nil}
end
...
Alternatively you can define generic pagination strategies by implementing a module
conforming to the JSONAPI.Paginator
behavior
defmodule PageBasedPaginator do
@moduledoc """
Page based pagination strategy
"""
@behaviour JSONAPI.Paginator
@impl true
def paginate(data, view, conn, page, options) do
number =
page
|> Map.get("page", "0")
|> String.to_integer()
size =
page
|> Map.get("size", "0")
|> String.to_integer()
total_pages = Keyword.get(options, :total_pages, 0)
%{
first: view.url_for_pagination(data, conn, Map.put(page, "page", "1")),
last: view.url_for_pagination(data, conn, Map.put(page, "page", total_pages)),
next: next_link(data, view, conn, number, size, total_pages),
prev: previous_link(data, view, conn, number, size)
}
end
defp next_link(data, view, conn, page, size, total_pages)
when page < total_pages,
do: view.url_for_pagination(data, conn, %{size: size, page: page + 1})
defp next_link(_data, _view, _conn, _page, _size, _total_pages),
do: nil
defp previous_link(data, view, conn, page, size)
when page > 1,
do: view.url_for_pagination(data, conn, %{size: size, page: page - 1})
defp previous_link(_data, _view, _conn, _page, _size),
do: nil
end
and configuring it as the global pagination logic in your mix.config
config :jsonapi, :paginator, PageBasedPaginator
or as the view pagination logic when using JSONAPI.View
use JSONAPI.View, paginator: PageBasedPaginator
Links can be generated using the JSONAPI.Config.page
information stored in the connection assign jsonapi_query
and by passing additional information to the pagination_links/4
callback or your paginator module by passing options
from your controller.
Actual pagination is expected to be handled in your application logic and is outside the scope of this library.
Other
- Feel free to make PR's. I will do my best to respond within a day or two.
- If you want to take one of the TODO items just create an issue or PR and let me know so we avoid duplication.
- If you need help, I am on irc and twitter.
- Example project