defmodule Plug.Parsers.JSON do
@moduledoc """
Parses JSON request body.
JSON arrays are parsed into a `"_json"` key to allow
proper param merging.
An empty request body is parsed as an empty map.
"""
@behaviour Plug.Parsers
import Plug.Conn
def parse(conn, "application", subtype, _headers, opts) do
if subtype == "json" || String.ends_with?(subtype, "+json") do
decoder = Keyword.get(opts, :json_decoder) ||
raise ArgumentError, "JSON parser expects a :json_decoder option"
conn
|> read_body(opts)
|> decode(decoder)
else
{:next, conn}
end
end
def parse(conn, _type, _subtype, _headers, _opts) do
{:next, conn}
end
defp decode({:more, _, conn}, _decoder) do
{:error, :too_large, conn}
end
defp decode({:ok, "", conn}, _decoder) do
{:ok, %{}, conn}
end
defp decode({:ok, body, conn}, decoder) do
case decoder.decode!(body) do
terms when is_map(terms) ->
{:ok, terms, conn}
terms ->
{:ok, %{"_json" => terms}, conn}
end
rescue
e -> raise Plug.Parsers.ParseError, exception: e
end
end