[Solved] Identify the error in this FastAPI route integrating LangChain and how to fix it: @app.post('/process') async def process(data: dict): result = chain.run(data['input']) return {'output': result} | LangChain

LangChain - Production Deployment

Identify the error in this FastAPI route integrating LangChain and how to fix it:

@app.post('/process')
async def process(data: dict):
    result = chain.run(data['input'])
    return {'output': result}

Achain.run is synchronous; should use await chain.arun for async call.

BMissing type annotation for data parameter.

CRoute should use @app.get instead of @app.post.

DReturn statement should return a string, not a dict.

Step-by-Step Solution

Solution:

Step 1: Check method call type in async function
Function is async but calls chain.run which is synchronous, causing blocking or errors.
Step 2: Fix by using async method
Replace chain.run with await chain.arun to properly await the async call.
Final Answer:
chain.run is synchronous; should use await chain.arun for async call. -> Option A
Quick Check:
Async function must await async calls [OK]

Quick Trick: Async functions must await async methods, not call sync ones [OK]

Common Mistakes:

MISTAKES

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