ollama[patch]: support standard image format (#30864)

Following #30746

Author: ccurme

libs/partners/ollama/langchain_ollama/chat_models.py

@@ -30,6 +30,7 @@
     SystemMessage,
     ToolCall,
     ToolMessage,
+    is_data_content_block,
 )
 from langchain_core.messages.ai import UsageMetadata
 from langchain_core.messages.tool import tool_call
@@ -173,6 +174,20 @@ def _lc_tool_call_to_openai_tool_call(tool_call: ToolCall) -> dict:
     }
 
 
+def _get_image_from_data_content_block(block: dict) -> str:
+    """Format standard data content block to format expected by Ollama."""
+    if block["type"] == "image":
+        if block["source_type"] == "base64":
+            return block["data"]
+        else:
+            error_message = "Image data only supported through in-line base64 format."
+            raise ValueError(error_message)
+
+    else:
+        error_message = f"Blocks of type {block['type']} not supported."
+        raise ValueError(error_message)
+
+
 def _is_pydantic_class(obj: Any) -> bool:
     return isinstance(obj, type) and is_basemodel_subclass(obj)
 
@@ -553,7 +568,9 @@ def _convert_messages_to_ollama_messages(
                             images.append(image_url_components[1])
                         else:
                             images.append(image_url_components[0])
-
+                    elif is_data_content_block(content_part):
+                        image = _get_image_from_data_content_block(content_part)
+                        images.append(image)
                     else:
                         raise ValueError(
                             "Unsupported message content type. "

libs/partners/ollama/tests/integration_tests/chat_models/test_chat_models_standard.py

@@ -14,14 +14,29 @@ def chat_model_class(self) -> type[ChatOllama]:
     def chat_model_params(self) -> dict:
         return {"model": "llama3.1"}
 
-    @property
-    def supports_image_inputs(self) -> bool:
-        return True
-
     @property
     def supports_json_mode(self) -> bool:
         return True
 
     @property
     def has_tool_choice(self) -> bool:
         return False
+
+
+def test_image_model() -> None:
+    class ImageModelTests(ChatModelIntegrationTests):
+        @property
+        def chat_model_class(self) -> type[ChatOllama]:
+            return ChatOllama
+
+        @property
+        def chat_model_params(self) -> dict:
+            return {"model": "gemma3:4b"}
+
+        @property
+        def supports_image_inputs(self) -> bool:
+            return True
+
+    test_instance = ImageModelTests()
+    model = test_instance.chat_model_class(**test_instance.chat_model_params)
+    ImageModelTests().test_image_inputs(model)