Improve contenttype detection logic for unregistered but common types.

Change get_contenttype to support common types which are or were not registered
with IANA, like image/webp or audio/midi.

Note: image/webp is already a IANA registered type and also added by
Products.MimetypesRegistry.

news/157-2.feature

@@ -0,0 +1,8 @@
+Improve contenttype detection logic for unregistered but common types.
+
+Change get_contenttype to support common types which are or were not registered
+with IANA, like image/webp or audio/midi.
+
+Note: image/webp is already a IANA registered type and also added by
+Products.MimetypesRegistry.
+[thet]

plone/namedfile/tests/test_image.py

@@ -89,23 +89,3 @@ def test_extract_media_type(self):
         self.assertEqual(extract("TEXT/PLAIN"), "text/plain")
         self.assertEqual(extract("text / plain"), "text/plain")
         self.assertEqual(extract(" text/plain ; charset=utf-8"), "text/plain")
-
-    def test_get_contenttype(self):
-        self.assertEqual(
-            get_contenttype(NamedImage(getFile("image.gif"), contentType="image/gif")),
-            "image/gif",
-        )
-        self.assertEqual(
-            get_contenttype(NamedImage(getFile("image.gif"), filename="image.gif")),
-            "image/gif",
-        )
-        self.assertEqual(
-            get_contenttype(NamedImage(getFile("image.tif"), filename="image.tif")),
-            "image/tiff",
-        )
-        self.assertEqual(
-            get_contenttype(
-                NamedImage(getFile("notimage.doc"), filename="notimage.doc")
-            ),
-            "application/msword",
-        )

plone/namedfile/tests/test_utils.py

@@ -0,0 +1,64 @@
+from plone.namedfile.file import NamedImage
+from plone.namedfile.tests import getFile
+from plone.namedfile.utils import get_contenttype
+
+import unittest
+
+
+class TestUtils(unittest.TestCase):
+
+    def test_get_contenttype(self):
+        self.assertEqual(
+            get_contenttype(
+                NamedImage(
+                    getFile("image.gif"),
+                    contentType="image/gif",
+                )
+            ),
+            "image/gif",
+        )
+        self.assertEqual(
+            get_contenttype(
+                NamedImage(
+                    getFile("image.gif"),
+                    filename="image.gif",
+                )
+            ),
+            "image/gif",
+        )
+        self.assertEqual(
+            get_contenttype(
+                NamedImage(
+                    getFile("image.tif"),
+                    filename="image.tif",
+                )
+            ),
+            "image/tiff",
+        )
+        self.assertEqual(
+            get_contenttype(
+                NamedImage(
+                    getFile("notimage.doc"),
+                    filename="notimage.doc",
+                )
+            ),
+            "application/msword",
+        )
+
+        # Filename only detection of a non-IANA registered type.
+        self.assertEqual(
+            get_contenttype(filename="image.webp"),
+            "image/webp",
+        )
+
+        # Filename only detection of a non-IANA registered type.
+        self.assertEqual(
+            get_contenttype(filename="song.midi"),
+            "audio/midi",
+        )
+
+        # Detection of a surely not registered type.
+        self.assertEqual(
+            get_contenttype(filename="nothing.plonenamedfile"),
+            "application/octet-stream",
+        )

plone/namedfile/utils/__init__.py

@@ -14,7 +14,6 @@
 from ZPublisher.Iterators import IStreamIterator
 
 import mimetypes
-import os.path
 import piexif
 import PIL.Image
 import re
@@ -126,8 +125,7 @@ def get_contenttype(file=None, filename=None, default="application/octet-stream"
 
     filename = getattr(file, "filename", filename)
     if filename:
-        extension = os.path.splitext(filename)[1].lower()
-        return mimetypes.types_map.get(extension, "application/octet-stream")
+        return mimetypes.guess_type(filename, strict=False)[0] or default
 
     return default