feat: enhance handling of prompt message content and add error for unsupported types

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/model_runtime/model_providers/__base/large_language_model.py

@@ -12,7 +12,9 @@ from core.model_runtime.entities.llm_entities import LLMResult, LLMResultChunk,
 from core.model_runtime.entities.message_entities import (
     AssistantPromptMessage,
     PromptMessage,
+    PromptMessageContent,
     PromptMessageTool,
+    TextPromptMessageContent,
 )
 from core.model_runtime.entities.model_entities import (
     ModelType,
@@ -211,7 +213,7 @@ class LargeLanguageModel(AIModel):
     def _invoke_result_generator(
         self,
         model: str,
-        result: Generator,
+        result: Generator[LLMResultChunk, None, None],
         credentials: dict,
         prompt_messages: list[PromptMessage],
         model_parameters: dict,
@@ -228,7 +230,7 @@ class LargeLanguageModel(AIModel):
         :return: result generator
         """
         callbacks = callbacks or []
-        assistant_message = AssistantPromptMessage(content="")
+        message_content: list[PromptMessageContent] = []
         usage = None
         system_fingerprint = None
         real_model = model
@@ -250,7 +252,10 @@ class LargeLanguageModel(AIModel):
                     callbacks=callbacks,
                 )
 
-                assistant_message.content += chunk.delta.message.content
+                if isinstance(chunk.delta.message.content, list):
+                    message_content.extend(chunk.delta.message.content)
+                elif isinstance(chunk.delta.message.content, str):
+                    message_content.append(TextPromptMessageContent(data=chunk.delta.message.content))
                 real_model = chunk.model
                 if chunk.delta.usage:
                     usage = chunk.delta.usage
@@ -260,6 +265,7 @@ class LargeLanguageModel(AIModel):
         except Exception as e:
             raise self._transform_invoke_error(e)
 
+        assistant_message = AssistantPromptMessage(content=message_content)
         self._trigger_after_invoke_callbacks(
             model=model,
             result=LLMResult(

api/core/workflow/nodes/llm/exc.py

@@ -38,3 +38,8 @@ class MemoryRolePrefixRequiredError(LLMNodeError):
 class FileTypeNotSupportError(LLMNodeError):
     def __init__(self, *, type_name: str):
         super().__init__(f"{type_name} type is not supported by this model")
+
+
+class UnsupportedPromptContentTypeError(LLMNodeError):
+    def __init__(self, *, type_name: str) -> None:
+        super().__init__(f"Prompt content type {type_name} is not supported.")

api/core/workflow/nodes/llm/node.py

@@ -19,7 +19,7 @@ from core.model_runtime.entities import (
     PromptMessageContentType,
     TextPromptMessageContent,
 )
-from core.model_runtime.entities.llm_entities import LLMResult, LLMUsage
+from core.model_runtime.entities.llm_entities import LLMResult, LLMResultChunk, LLMUsage
 from core.model_runtime.entities.message_entities import (
     AssistantPromptMessage,
     PromptMessageContent,
@@ -78,6 +78,7 @@ from .exc import (
     ModelNotExistError,
     NoPromptFoundError,
     TemplateTypeNotSupportError,
+    UnsupportedPromptContentTypeError,
     VariableNotFoundError,
 )
 
@@ -246,56 +247,62 @@ class LLMNode(BaseNode[LLMNodeData]):
 
         return self._handle_invoke_result(invoke_result=invoke_result)
 
-    def _handle_invoke_result(self, invoke_result: LLMResult | Generator) -> Generator[NodeEvent, None, None]:
+    def _handle_invoke_result(
+        self, invoke_result: LLMResult | Generator[LLMResultChunk, None, None]
+    ) -> Generator[NodeEvent, None, None]:
+        # For blocking mode
         if isinstance(invoke_result, LLMResult):
-            content = invoke_result.message.content
+            event = self._handle_blocking_result(invoke_result=invoke_result)
-            if content is None:
+            yield event
-                message_text = ""
-            elif isinstance(content, str):
-                message_text = content
-            elif isinstance(content, list):
-                # Assuming the list contains PromptMessageContent objects with a "data" attribute
-                message_text = "".join(
-                    item.data if hasattr(item, "data") and isinstance(item.data, str) else str(item) for item in content
-                )
-            else:
-                message_text = str(content)
-
-            yield ModelInvokeCompletedEvent(
-                text=message_text,
-                usage=invoke_result.usage,
-                finish_reason=None,
-            )
             return
 
-        model = None
+        # For streaming mode
+        model = ""
         prompt_messages: list[PromptMessage] = []
         full_text = ""
-        usage = None
+        usage = LLMUsage.empty_usage()
         finish_reason = None
         for result in invoke_result:
-            text = result.delta.message.content
+            contents = result.delta.message.content
-            full_text += text
+            if contents is None:
+                continue
 
-            yield RunStreamChunkEvent(chunk_content=text, from_variable_selector=[self.node_id, "text"])
+            if isinstance(contents, str):
+                yield RunStreamChunkEvent(chunk_content=contents, from_variable_selector=[self.node_id, "text"])
+                full_text += contents
+            elif isinstance(contents, list):
+                for content in contents:
+                    if isinstance(content, TextPromptMessageContent):
+                        text_chunk = content.data
+                    elif isinstance(content, ImagePromptMessageContent):
+                        text_chunk = self._image_to_markdown(content)
+                    else:
+                        raise UnsupportedPromptContentTypeError(type_name=str(type(content)))
+                    yield RunStreamChunkEvent(chunk_content=text_chunk, from_variable_selector=[self.node_id])
+                    full_text += text_chunk
 
-            if not model:
+            # Update the whole metadata
+            if not model and result.model:
                 model = result.model
-
+            if len(prompt_messages) == 0:
-            if not prompt_messages:
                 prompt_messages = result.prompt_messages
-
+            if usage.prompt_tokens == 0 and result.delta.usage:
-            if not usage and result.delta.usage:
                 usage = result.delta.usage
-
+            if finish_reason is None and result.delta.finish_reason:
-            if not finish_reason and result.delta.finish_reason:
                 finish_reason = result.delta.finish_reason
 
-        if not usage:
-            usage = LLMUsage.empty_usage()
-
         yield ModelInvokeCompletedEvent(text=full_text, usage=usage, finish_reason=finish_reason)
 
+    def _image_to_markdown(self, content: ImagePromptMessageContent, /):
+        if content.url:
+            text_chunk = f"![]({content.url})"
+        elif content.base64_data:
+            # insert b64 image into markdown text
+            text_chunk = f"![]({content.data})"
+        else:
+            raise ValueError("Image content must have either a URL or base64 data")
+        return text_chunk
+
     def _transform_chat_messages(
         self, messages: Sequence[LLMNodeChatModelMessage] | LLMNodeCompletionModelPromptTemplate, /
     ) -> Sequence[LLMNodeChatModelMessage] | LLMNodeCompletionModelPromptTemplate:
@@ -926,6 +933,31 @@ class LLMNode(BaseNode[LLMNodeData]):
 
         return prompt_messages
 
+    def _handle_blocking_result(self, *, invoke_result: LLMResult) -> ModelInvokeCompletedEvent:
+        contents = invoke_result.message.content
+        if contents is None:
+            message_text = ""
+        elif isinstance(contents, str):
+            message_text = contents
+        elif isinstance(contents, list):
+            # TODO: support multi modal content
+            message_text = ""
+            for item in contents:
+                if isinstance(item, TextPromptMessageContent):
+                    message_text += item.data
+                elif isinstance(item, ImagePromptMessageContent):
+                    message_text += self._image_to_markdown(item)
+                else:
+                    message_text += str(item)
+        else:
+            message_text = str(contents)
+
+        return ModelInvokeCompletedEvent(
+            text=message_text,
+            usage=invoke_result.usage,
+            finish_reason=None,
+        )
+
 
 def _combine_message_content_with_role(*, contents: Sequence[PromptMessageContent], role: PromptMessageRole):
     match role: