fix: fixed workflow as tool files field return empty problem (#27925)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: QuantumGhost <obelisk.reg+git@gmail.com>

api/core/workflow/nodes/tool/tool_node.py

@@ -329,7 +329,15 @@ class ToolNode(Node):
                     json.append(message.message.json_object)
             elif message.type == ToolInvokeMessage.MessageType.LINK:
                 assert isinstance(message.message, ToolInvokeMessage.TextMessage)
+
+                # Check if this LINK message is a file link
+                file_obj = (message.meta or {}).get("file")
+                if isinstance(file_obj, File):
+                    files.append(file_obj)
+                    stream_text = f"File: {message.message.text}\n"
+                else:
                     stream_text = f"Link: {message.message.text}\n"
+
                 text += stream_text
                 yield StreamChunkEvent(
                     selector=[node_id, "text"],

api/tests/unit_tests/core/workflow/nodes/tool/test_tool_node.py

@@ -0,0 +1,160 @@
+import sys
+import types
+from collections.abc import Generator
+from typing import TYPE_CHECKING, Any
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from core.file import File, FileTransferMethod, FileType
+from core.model_runtime.entities.llm_entities import LLMUsage
+from core.tools.entities.tool_entities import ToolInvokeMessage
+from core.tools.utils.message_transformer import ToolFileMessageTransformer
+from core.variables.segments import ArrayFileSegment
+from core.workflow.entities import GraphInitParams
+from core.workflow.node_events import StreamChunkEvent, StreamCompletedEvent
+from core.workflow.runtime import GraphRuntimeState, VariablePool
+from core.workflow.system_variable import SystemVariable
+
+if TYPE_CHECKING:  # pragma: no cover - imported for type checking only
+    from core.workflow.nodes.tool.tool_node import ToolNode
+
+
+@pytest.fixture
+def tool_node(monkeypatch) -> "ToolNode":
+    module_name = "core.ops.ops_trace_manager"
+    if module_name not in sys.modules:
+        ops_stub = types.ModuleType(module_name)
+        ops_stub.TraceQueueManager = object  # pragma: no cover - stub attribute
+        ops_stub.TraceTask = object  # pragma: no cover - stub attribute
+        monkeypatch.setitem(sys.modules, module_name, ops_stub)
+
+    from core.workflow.nodes.tool.tool_node import ToolNode
+
+    graph_config: dict[str, Any] = {
+        "nodes": [
+            {
+                "id": "tool-node",
+                "data": {
+                    "type": "tool",
+                    "title": "Tool",
+                    "desc": "",
+                    "provider_id": "provider",
+                    "provider_type": "builtin",
+                    "provider_name": "provider",
+                    "tool_name": "tool",
+                    "tool_label": "tool",
+                    "tool_configurations": {},
+                    "tool_parameters": {},
+                },
+            }
+        ],
+        "edges": [],
+    }
+
+    init_params = GraphInitParams(
+        tenant_id="tenant-id",
+        app_id="app-id",
+        workflow_id="workflow-id",
+        graph_config=graph_config,
+        user_id="user-id",
+        user_from="account",
+        invoke_from="debugger",
+        call_depth=0,
+    )
+
+    variable_pool = VariablePool(system_variables=SystemVariable(user_id="user-id"))
+    graph_runtime_state = GraphRuntimeState(variable_pool=variable_pool, start_at=0.0)
+
+    config = graph_config["nodes"][0]
+    node = ToolNode(
+        id="node-instance",
+        config=config,
+        graph_init_params=init_params,
+        graph_runtime_state=graph_runtime_state,
+    )
+    node.init_node_data(config["data"])
+    return node
+
+
+def _collect_events(generator: Generator) -> tuple[list[Any], LLMUsage]:
+    events: list[Any] = []
+    try:
+        while True:
+            events.append(next(generator))
+    except StopIteration as stop:
+        return events, stop.value
+
+
+def _run_transform(tool_node: "ToolNode", message: ToolInvokeMessage) -> tuple[list[Any], LLMUsage]:
+    def _identity_transform(messages, *_args, **_kwargs):
+        return messages
+
+    tool_runtime = MagicMock()
+    with patch.object(ToolFileMessageTransformer, "transform_tool_invoke_messages", side_effect=_identity_transform):
+        generator = tool_node._transform_message(
+            messages=iter([message]),
+            tool_info={"provider_type": "builtin", "provider_id": "provider"},
+            parameters_for_log={},
+            user_id="user-id",
+            tenant_id="tenant-id",
+            node_id=tool_node._node_id,
+            tool_runtime=tool_runtime,
+        )
+        return _collect_events(generator)
+
+
+def test_link_messages_with_file_populate_files_output(tool_node: "ToolNode"):
+    file_obj = File(
+        tenant_id="tenant-id",
+        type=FileType.DOCUMENT,
+        transfer_method=FileTransferMethod.TOOL_FILE,
+        related_id="file-id",
+        filename="demo.pdf",
+        extension=".pdf",
+        mime_type="application/pdf",
+        size=123,
+        storage_key="file-key",
+    )
+    message = ToolInvokeMessage(
+        type=ToolInvokeMessage.MessageType.LINK,
+        message=ToolInvokeMessage.TextMessage(text="/files/tools/file-id.pdf"),
+        meta={"file": file_obj},
+    )
+
+    events, usage = _run_transform(tool_node, message)
+
+    assert isinstance(usage, LLMUsage)
+
+    chunk_events = [event for event in events if isinstance(event, StreamChunkEvent)]
+    assert chunk_events
+    assert chunk_events[0].chunk == "File: /files/tools/file-id.pdf\n"
+
+    completed_events = [event for event in events if isinstance(event, StreamCompletedEvent)]
+    assert len(completed_events) == 1
+    outputs = completed_events[0].node_run_result.outputs
+    assert outputs["text"] == "File: /files/tools/file-id.pdf\n"
+
+    files_segment = outputs["files"]
+    assert isinstance(files_segment, ArrayFileSegment)
+    assert files_segment.value == [file_obj]
+
+
+def test_plain_link_messages_remain_links(tool_node: "ToolNode"):
+    message = ToolInvokeMessage(
+        type=ToolInvokeMessage.MessageType.LINK,
+        message=ToolInvokeMessage.TextMessage(text="https://dify.ai"),
+        meta=None,
+    )
+
+    events, _ = _run_transform(tool_node, message)
+
+    chunk_events = [event for event in events if isinstance(event, StreamChunkEvent)]
+    assert chunk_events
+    assert chunk_events[0].chunk == "Link: https://dify.ai\n"
+
+    completed_events = [event for event in events if isinstance(event, StreamCompletedEvent)]
+    assert len(completed_events) == 1
+    files_segment = completed_events[0].node_run_result.outputs["files"]
+    assert isinstance(files_segment, ArrayFileSegment)
+    assert files_segment.value == []