api.views.MimeType as normal class (mime types need to be str, not su…

…bclasses)

egsim/api/views.py

@@ -1,7 +1,6 @@
 """Module with the views for the web API (no GUI)"""
 from __future__ import annotations
 from collections.abc import Callable, Iterable
-from enum import StrEnum
 from http.client import responses
 from datetime import date, datetime
 import re
@@ -26,16 +25,18 @@
 from .forms.flatfile.residuals import ResidualsForm
 
 
-class MIMETYPE(StrEnum):  # noqa
-    """An enum of supported mime types (content_type in Django Response) loosely
+class MimeType:  # noqa
+    """A collection of supported mime types (content_type in Django Response), loosely
     copied from mimetypes.types_map (https://docs.python.org/3.8/library/mimetypes.html)
     """
-    CSV = "text/csv"
-    JSON = "application/json"
-    HDF = "application/x-hdf"
-    PNG = "image/png"
-    PDF = "application/pdf"
-    SVG = "image/svg+xml"
+    # NOTE: avoid Enums or alike, attributes below will be passed as `content_type` arg
+    # to Responses and must be pure str (subclasses NOT allowed!)
+    csv = "text/csv"
+    json = "application/json"
+    hdf = "application/x-hdf"
+    png = "image/png"
+    pdf = "application/pdf"
+    svg = "image/svg+xml"
     # GZIP = "application/gzip"
 
 
@@ -129,10 +130,9 @@ def response(self, **form_kwargs):
         :param form_kwargs: keyword arguments to be passed to this class Form
         """
         try:
-            rformat = form_kwargs['data'].pop('format', MIMETYPE.JSON.name.lower())
+            rformat = form_kwargs['data'].pop('format', 'json')
             try:
-                mimetype = MIMETYPE[rformat.upper()]
-                response_function = self.supported_formats()[mimetype]
+                response_function = self.supported_formats()[rformat]
             except KeyError:
                 raise ValidationError(f'Invalid format {rformat}')
             form = self.formclass(**form_kwargs)
@@ -147,21 +147,19 @@ def response(self, **form_kwargs):
 
     @classmethod
     def supported_formats(cls) -> \
-            dict[MIMETYPE, Callable[[RESTAPIView, APIForm], HttpResponse]]:
+            dict[str, Callable[[RESTAPIView, APIForm], HttpResponse]]:
         """Return a list of supported formats (content_types) by inspecting
-        this class implemented methods. Each dict key is a MIMETYPE enum,
-        mapped to this class method used to obtain the response data in that
+        this class implemented methods. Each dict key is a MimeType attr name,
+        mapped to a class method used to obtain the response data in that
         mime type"""
         formats = {}
         for a in dir(cls):
             if a.startswith('response_'):
                 meth = getattr(cls, a)
                 if callable(meth):
                     frmt = a.split('_', 1)[1]
-                    try:
-                        formats[MIMETYPE[frmt.upper()]] = meth
-                    except KeyError:
-                        pass
+                    if hasattr(MimeType, frmt):
+                        formats[frmt] = meth
         return formats
 
     def response_json(self, form:APIForm) -> JsonResponse:
@@ -181,10 +179,10 @@ class TrellisView(RESTAPIView):
     urls = (f'{API_PATH}/trellis', f'{API_PATH}/model-model-comparison')
 
     def response_csv(self, form:APIForm):
-        return pandas_response(form.response_data(), MIMETYPE.CSV)
+        return pandas_response(form.response_data(), MimeType.csv)
 
     def response_hdf(self, form:APIForm):
-        return pandas_response(form.response_data(), MIMETYPE.HDF)
+        return pandas_response(form.response_data(), MimeType.hdf)
 
     def response_json(self, form:APIForm) -> JsonResponse:
         json_data = dataframe2dict(form.response_data(),
@@ -199,10 +197,10 @@ class ResidualsView(RESTAPIView):
     urls = (f'{API_PATH}/residuals', f'{API_PATH}/model-data-comparison')
 
     def response_csv(self, form:APIForm):
-        return pandas_response(form.response_data(), MIMETYPE.CSV)
+        return pandas_response(form.response_data(), MimeType.csv)
 
     def response_hdf(self, form:APIForm):
-        return pandas_response(form.response_data(), MIMETYPE.HDF)
+        return pandas_response(form.response_data(), MimeType.hdf)
 
     def response_json(self, form:APIForm) -> JsonResponse:
         json_data = dataframe2dict(form.response_data(),
@@ -236,25 +234,25 @@ def error_response(error: Union[str, Exception, dict],
         else:
             message = str(error)
     content.setdefault('message', message)
-    kwargs.setdefault('content_type', MIMETYPE.JSON)
+    kwargs.setdefault('content_type', MimeType.json)
     return JsonResponse(content, status=status, **kwargs)
 
 
-def pandas_response(data:pd.DataFrame, content_type:Optional[MIMETYPE]=None,
+def pandas_response(data:pd.DataFrame, content_type:Optional[str]=None,
                     status=200, reason=None, headers=None, charset=None,
                     as_stream=False) -> HttpResponseBase:  # usually FileResponse
     """Return a `HTTPResponse` for serving pandas dataframes as either HDF or CSV
 
-    :param content_type: optional content type. Either MIMETYPE.CSV or MIMETYPE.HDF
-        If None, it defaults to the former.
+    :param content_type: optional content type. See MimeType attr values. Defaults to
+        `MimeType.csv`
     :param as_stream: if False (the default) return a `FileResponse`, otherwise
         a `StreamingHttpResponse`
     """
     if content_type is None:  # the default is CSV:
-        content_type = MIMETYPE.CSV
-    if content_type == MIMETYPE.CSV:
+        content_type = MimeType.csv
+    if content_type == MimeType.csv:
         content = write_csv_to_buffer(data)
-    elif content_type == MIMETYPE.HDF:
+    elif content_type == MimeType.hdf:
         content = write_hdf_to_buffer({'egsim': data})
     else:
         return error_response(f'cannot serve {data.__class__.__name__} '

egsim/app/views.py

@@ -21,7 +21,7 @@
                                               FlatfileInspectionForm, FlatfilePlotForm)
 from ..api.forms import GsimFromRegionForm
 from ..api.views import (error_response, RESTAPIView, TrellisView, ResidualsView,
-                         MIMETYPE)
+                         MimeType)
 
 
 def main(request, selected_menu=None):
@@ -107,7 +107,7 @@ def download_request(request, key: TAB, filename: str):
     :param key: a :class:`TAB` name associated to a REST API TAB (i.e.,
         with an associated Form class)
     """
-    form_class = TAB[key].formclass
+    form_class = TAB[key].formclass  # FIXME remove pycharm lint warning
 
     def input_dict() -> dict:
         """return the input dict. This function allows to work each time
@@ -144,9 +144,8 @@ def download_response(request, key: TAB, filename: str):
     elif ext == '.csv_eu':
         return download_ascsv(request, key, basename + '.csv', ';', ',')
     try:
-        content_type = MIMETYPE[ext[1:].upper()]
-        return download_asimage(request, filename, content_type)
-    except KeyError:
+        return download_asimage(request, filename, ext[1:])
+    except AttributeError:
         pass  # filename extension not recognized as image
     return error_response(f'Unsupported format "{ext[1:]}"',
                           RESTAPIView.CLIENT_ERR_CODE)
@@ -171,20 +170,11 @@ def download_ascsv(request, key: TAB, filename: str, sep=',', dec='.'):
     return response
 
 
-# FIXME: remove
-# _IMG_FORMATS = {
-#     # 'eps': 'application/postscript',  # NA (note: requires poppler library in case)
-#     'pdf': 'application/pdf',
-#     'svg': 'image/svg+xml',
-#     'png': 'image/png'
-# }
-
-
-def download_asimage(request, filename: str, content_type: MIMETYPE) -> FileResponse:
+def download_asimage(request, filename: str, img_format: str) -> FileResponse:
     """Return the image from the given request built in the frontend GUI
     according to the chosen plots
     """
-    img_format = content_type.name.lower()
+    content_type = getattr(MimeType, img_format)
     if not filename.lower().endswith(f".{img_format}"):
         filename += f".{img_format}"
     jsondata = json.loads(request.body.decode('utf-8'))