feat: Automatically determine mime_type for Part.from_uri

PiperOrigin-RevId: 749089175

Author: matthew29tang

google/genai/tests/models/test_generate_content_part.py

@@ -467,9 +467,10 @@ def test_from_uploaded_file_uri(client):
         ],
     )
 
-def test_from_uri_error(client):
-  # missing mime_type
-  with pytest.raises(TypeError):
+
+def test_from_uri_inferred_mime_type(client):
+  # gs://generativeai-downloads/images/scones.jpg isn't supported in MLDev
+  with pytest_helper.exception_if_mldev(client, errors.ClientError):
     client.models.generate_content(
         model='gemini-1.5-flash',
         contents=[
@@ -481,6 +482,20 @@ def test_from_uri_error(client):
     )
 
 
+def test_from_uri_invalid_inferred_mime_type(client):
+  # Throws ValueError if mime_type cannot be inferred.
+  with pytest.raises(ValueError):
+    client.models.generate_content(
+        model='gemini-1.5-flash',
+        contents=[
+            'What is this image about?',
+            types.Part.from_uri(
+                file_uri='uri/without/mime/type'
+            ),
+        ],
+    )
+
+
 def test_audio_uri(client):
   with pytest_helper.exception_if_mldev(client, errors.ClientError):
     client.models.generate_content(

google/genai/tests/types/test_types.py

@@ -41,6 +41,19 @@ def test_factory_method_from_uri_part():
   assert isinstance(my_part, SubPart)
 
 
+def test_factory_method_from_uri_inferred_mime_type_part():
+
+  my_part = SubPart.from_uri(
+      file_uri='gs://generativeai-downloads/images/scones.jpg',
+  )
+  assert (
+      my_part.file_data.file_uri
+      == 'gs://generativeai-downloads/images/scones.jpg'
+  )
+  assert my_part.file_data.mime_type == 'image/jpeg'
+  assert isinstance(my_part, SubPart)
+
+
 def test_factory_method_from_text_part():
   my_part = SubPart.from_text(text='What is your name?')
   assert my_part.text == 'What is your name?'

google/genai/types.py

@@ -642,7 +642,22 @@ class Part(_common.BaseModel):
   )
 
   @classmethod
-  def from_uri(cls, *, file_uri: str, mime_type: str) -> 'Part':
+  def from_uri(
+      cls, *, file_uri: str, mime_type: Optional[str] = None
+  ) -> 'Part':
+    """Creates a Part from a file uri.
+
+    Args:
+      file_uri (str): The uri of the file
+      mime_type (str): mime_type: The MIME type of the image. If not provided,
+        the MIME type will be automatically determined.
+    """
+    if mime_type is None:
+      import mimetypes
+
+      mime_type, _ = mimetypes.guess_type(file_uri)
+      if not mime_type:
+        raise ValueError(f'Failed to determine mime type for file: {file_uri}')
     file_data = FileData(file_uri=file_uri, mime_type=mime_type)
     return cls(file_data=file_data)