[bug] workflow as tool files field return is empty #26431
Description
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Dify version
1.9.0
Cloud or Self Hosted
Self Hosted (Source)
Steps to reproduce
- create a new workflow, add one generate file plugin, I use
md_exporter
md_exporter tool files field have correct return
- publish this workflow to tool
- add this tool at another workflow and run it, watch the common tool field
files, and it will found nothing
log here:
[on_tool_execution]
Tool: md_to_pdf
Outputs: {"type":"blob","message":{"blob":"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
[on_tool_execution]
Tool: test
Outputs: {"type":"file","message":{},"meta":{"file":{"dify_model_identity":"__dify__file__","id":null,"tenant_id":"b7df5634-8029-4c6d-969f-c39e9f7ae646","type":"document","transfer_method":"tool_file","remote_url":null,"related_id":"daa5807b-bf1b-429b-a0c4-c792c2b43d45","filename":"15af481b86264b548b1a9e59a5248406.pdf","extension":".pdf","mime_type":"application/pdf","size":1954}}}
[on_tool_execution]
Tool: test
Outputs: {"type":"text","message":{"text":"{\"files1\": [{\"dify_model_identity\": \"__dify__file__\", \"id\": null, \"tenant_id\": \"b7df5634-8029-4c6d-969f-c39e9f7ae646\", \"type\": \"document\", \"transfer_method\": \"tool_file\", \"remote_url\": null, \"related_id\": \"daa5807b-bf1b-429b-a0c4-c792c2b43d45\", \"filename\": \"15af481b86264b548b1a9e59a5248406.pdf\", \"extension\": \".pdf\", \"mime_type\": \"application/pdf\", \"size\": 1954, \"url\": \"http://127.0.0.1:5001/files/tools/daa5807b-bf1b-429b-a0c4-c792c2b43d45.pdf?timestamp=1759128236&nonce=8b229fa50d6df2eb787765a40f502d99&sign=ymEk1BfpL3dDGOZPmtPYY0zYTUb_MJ-co3ZOcFclRs0=\", \"tool_file_id\": \"daa5807b-bf1b-429b-a0c4-c792c2b43d45\"}]}"},"meta":null}
[on_tool_execution]
Tool: test
Outputs: {"type":"json","message":{"json_object":{"files1":[{"dify_model_identity":"__dify__file__","id":null,"tenant_id":"b7df5634-8029-4c6d-969f-c39e9f7ae646","type":"document","transfer_method":"tool_file","remote_url":null,"related_id":"daa5807b-bf1b-429b-a0c4-c792c2b43d45","filename":"15af481b86264b548b1a9e59a5248406.pdf","extension":".pdf","mime_type":"application/pdf","size":1954,"url":"http://127.0.0.1:5001/files/tools/daa5807b-bf1b-429b-a0c4-c792c2b43d45.pdf?timestamp=1759128236&nonce=8b229fa50d6df2eb787765a40f502d99&sign=ymEk1BfpL3dDGOZPmtPYY0zYTUb_MJ-co3ZOcFclRs0=","tool_file_id":"daa5807b-bf1b-429b-a0c4-c792c2b43d45"}]}},"meta":null}
Actually, the tool of workflow as tool create file message correctly, but at last we got nothing at files field.
✔️ Expected Behavior
Workflow as tool files field return all files which this tool generated.
❌ Actual Behavior
Workflow as tool files field return empty.
Here is relative issue: #18375
This issue mentioned pr #18427 is revertd by this pr #24061, because it introduce some new bug, but this behavior actually not correct, we need to fix it.
Thanks copilot agent, I found the problem maybe about this code:
dify/api/core/tools/utils/message_transformer.py
Lines 137 to 157 in 1a7898d
The tool of workflow as tool return content relate message, and all workflow message will transform by message_transformer.py, at here it will transform file to link, and then when tool_node.py to handle message stream, it will goto message.type == ToolInvokeMessage.MessageType.LINK case, so that this tool files field return nothing.