Neither Flask nor Flask-RESTful includes the declaration of variables for the different HTTP status codes. We don't want to return numbers as status codes. We want our code to be easy to read and understand, and therefore, we will use descriptive HTTP status codes. Specifically, we will take advantage of the support for enumerations added in Python 3.4 to declare a class that defines unique sets of names and values that represent the different HTTP status codes.
First, create a service folder within the root folder for the recently created virtual environment. Create a new http_status.py file within the service folder. The following lines show the code that declares the HttpStatus class that inherits from the enum.Enum class. The code file for the sample is included in the restful_python_2_01_01 folder, in the Flask01/service/http_status.py file:
from enum import Enum
class HttpStatus(Enum):
continue_100 = 100
switching_protocols_101 = 101
ok_200 = 200
created_201 = 201
accepted_202 = 202
non_authoritative_information_203 = 203
no_content_204 = 204
reset_content_205 = 205
partial_content_206 = 206
multiple_choices_300 = 300
moved_permanently_301 = 301
found_302 = 302
see_other_303 = 303
not_modified_304 = 304
use_proxy_305 = 305
reserved_306 = 306
temporary_redirect_307 = 307
bad_request_400 = 400
unauthorized_401 = 401
payment_required_402 = 402
forbidden_403 = 403
not_found_404 = 404
method_not_allowed_405 = 405
not_acceptable_406 = 406
proxy_authentication_required_407 = 407
request_timetout_408 = 408
conflict_409 = 409
gone_410 = 410
length_required_411 = 411
precondition_failed_412 = 412
request_entity_too_large_413 = 413
request_uri_too_long_414 = 414
unsupported_media_type_415 = 415
requested_range_not_satisfiable_416 = 416
expectation_failed_417 = 417
precondition_required_428 = 428
too_many_requests_429 = 429
request_header_fields_too_large_431 = 431
unavailable_for_legal_reasons_451 = 451
internal_server_error_500 = 500
not_implemented_501 = 501
bad_gateway_502 = 502
service_unavailable_503 = 503
gateway_timeout_504 = 504
http_version_not_supported_505 = 505
network_authentication_required_511 = 511
@staticmethod
def is_informational(cls, status_code):
return 100 <= status_code.value <= 199
@staticmethod
def is_success(status_code):
return 200 <= status_code.value <= 299
@staticmethod
def is_redirect(status_code):
return 300 <= status_code.value <= 399
@staticmethod
def is_client_error(status_code):
return 400 <= status_code.value <= 499
@staticmethod
def is_server_error(status_code):
return 500 <= status_code.value <= 599 The HttpStatus class defines unique sets of names and values that represent the different HTTP status codes. The names use the description as a prefix and the HTTP status code number as a suffix. For example, the 200 value of the HTTP 200 OK status code is defined in the HttpStatus.ok_200 name, and the HTTP 404 Not Found status code is defined in the HttpStatus.not_found_404 name.
Note
We will use the names defined in the enumerable to return a specific status code whenever necessary in our code. For example, in case we have to return an HTTP 404 Not Found status code, we will return HttpStatus.not_found_404.value, instead of just 404. This way, it will be easier to understand the code because we won't have to remember the meaning of each number.
In addition, the HttpStatus class declares five static methods that receive any of the HTTP status codes defined in the enumerable as an argument and determines which of the following categories the status code belongs to: informational, success, redirect, client error, or server error.