Parses a JSON:API query parameter to a user defined format.

You can implement a custom format for JSON:API query parameters that do not define a standard format: filter, page and sort.

To customize the default parser implement a module adopting the JSONAPIPlug.QueryParser behaviour for your sort format:

defmodule MyApp.API.QueryParsers.Sort do
  ...
  @behaviour JSONAPIPlug.QueryParser

  # Transforms the query parameter value to a user defined format
  @impl JSONAPIPlug.QueryParser
  def parse(jsonapi_plug, sort) do
    ...my sort query parameter parsing logic...
  end
end

and configure it in your API configuration under the parsers key.

config :my_app, MyApp.API,
  parsers: [
    filter: MyApp.API.QueryParser.Filter,
    page: MyApp.API.QueryParser.Page,
    sort: MyApp.API.QueryParser.Sort
  ]

The parsers take the query parameter value as input and its return value is placed under an attribute with the same name as the query parameter in the JSONAPIPlug structure in the conn private assigns so that you can retrieve it and use it in your application logic.

You can return a standard JSON:API error to the client by raising JSONAPIPlug.Exceptions.InvalidQuery exception at any point in your parser code.