Inquisitor query handlers for JSON API filters

JSON API Spec

Usage

use the module after the Inquisitor module:

defmodule MyApp do
  use Inquisitor
  use Inquisitor.JsonApi.Filter

  ...
end

This module allows you to decide how you want to handle filter key/value params. For example you may query your API with the following URL:

https://example.com/posts?filter[foo]=bar&filter[baz]=qux

You can use build_filter_query/4 to define matchers:

def build_filter_query(query, "foo", value, _conn) do
  Ecto.Query.where(query, [r], r.foo == ^value)
end

def build_filter_query(query, "baz", value, _conn) do
  Ecto.Query.where(query, [r], r.baz > ^value)
end

General key/value matcher

You may want a handler that simply queries on key/value pairs. Use the following:

def build_filter_query(query, key, value, _conn) do
  Ecto.Query.where(query, [r], Ecto.Query.API.field(r, ^String.to_existing_atom(key)) == ^value)
end

Security

This module is secure by default. Meaning that you must opt-in to handle the filter params. Otherwise they are ignored by the query builder.

If you would like to limit the values to act upon use a guard:

@filter_whitelist ~w(name title)
def build_filter_query(query, key, value, _conn) where key in @filter_whitelist do
  Ecto.Query.where(query, [r], Ecto.Query.API.field(r, ^String.to_existing_atom(key)) == ^value)
end