defmodule Hibana.Plugins.ErrorHandler do
@moduledoc """
Custom error handler plugin for HTTP errors.
## Features
- Custom 404 (Not Found) handlers
- Custom 500 (Server Error) handlers
- HTML and JSON response formats
- Pluggable error rendering functions
## Usage
# Basic usage
plug Hibana.Plugins.ErrorHandler
# With custom handlers
plug Hibana.Plugins.ErrorHandler,
not_found: &my_not_found_handler/1,
server_error: &my_error_handler/1
## Options
- `:not_found` - Custom 4xx error handler function
- `:server_error` - Custom 5xx error handler function
## Handler Functions
Custom handler receives the conn:
def my_not_found_handler(conn) do
json(conn, %{error: "Resource not found"})
end
def my_error_handler(conn) do
json(conn, %{error: "Internal server error"})
end
## Default Responses
**404 Not Found:**
HTTP 404
404 - Not Found
**500 Server Error:**
HTTP 500
500 - Internal Server Error
"""
use Hibana.Plugin
import Plug.Conn
@impl true
def init(opts) do
%{
not_found: Keyword.get(opts, :not_found, :default),
server_error: Keyword.get(opts, :server_error, :default)
}
end
@impl true
def call(conn, %{not_found: not_found_handler, server_error: server_error_handler}) do
conn
|> assign(:error_not_found, not_found_handler)
|> assign(:error_server_error, server_error_handler)
end
@impl true
def before_send(%{status: status} = conn, _opts) when status >= 400 and status < 500 do
handler = Map.get(conn.assigns, :error_not_found, :default)
apply_handler(conn, handler, :not_found)
end
@impl true
def before_send(%{status: status} = conn, _opts) when status >= 500 do
handler = Map.get(conn.assigns, :error_server_error, :default)
apply_handler(conn, handler, :server_error)
end
@impl true
def before_send(conn, _opts), do: conn
defp apply_handler(conn, :default, :not_found), do: default_not_found(conn)
defp apply_handler(conn, :default, :server_error), do: default_server_error(conn)
defp apply_handler(conn, fun, _type) when is_function(fun, 1), do: fun.(conn)
defp apply_handler(conn, {mod, fun}, _type), do: apply(mod, fun, [conn])
defp apply_handler(conn, {mod, fun, args}, _type), do: apply(mod, fun, [conn | args])
defp default_not_found(conn) do
%{conn | resp_body: "404 - Not Found
"}
|> put_resp_content_type("text/html")
end
defp default_server_error(conn) do
%{conn | resp_body: "500 - Internal Server Error
"}
|> put_resp_content_type("text/html")
end
end