Cannot use httpAction to send langgraph streaming events
I want to use
httpAction to build an api for streaming events that produced by langgraph.js, below is what I do and errors I had encountered:
1. First, I made a very simple demo, only produce stream events by using langchain's openai model provider, is works fine
2. Next, I wrote a relative complex langgraph agent (I'm sure it works), this time convex throw an error to inform using "use node"
3. Since httpAction does not allow "use node", I extract all agent codes into a internal action
4. Then I invoke this internal action in httpAction to get the stream, and I saw this error:
It seems like I can't return a IterableReadableStreamWithAbortSignal object (which generated by langgraphagent.streamEvents method) through internalAction? What can I do to make it work?
UPDATE: After a step-by-step debug, I can confirm the problem is caused by this line:
If I put this line in the httpAction, it errors because it depends on "node:async_hooks" which requires using "use node" directive
If I move this line to an internalAction and return the result, Convex will complain CompiledStateGraph is not a supported Convex type
I was trapped at this step, anyone can help me out?2 Replies
Thanks for posting in <#1088161997662724167>.
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Thank you!
The arguments going into Convex functions and the return values going out must be serializable, and must conform to the allowable types for Convex function I/O. You can see a list of supported types here: https://docs.convex.dev/functions/validation#supported-types
So you wouldn't be able to return a readable stream as is from a Convex function, only a serializable representation.
I haven't worked with streaming so I'm not a ton of help, but the persistent text streaming component does give a working example of utilizing
TransformStream to run streams through http actions in the Convex runtime (no "use node"), and persisting state in a serializable way through Convex functions: https://github.com/get-convex/persistent-text-streaming/blob/e080e1216dbfa5bdd730e80df30a243578685c81/src/client/index.ts#L87-L171