[Solved] What is the issue with this LangServe class? class MultiplyAPI: def multiply(self, input): return input * 2 | LangChain

LangChain - Production Deployment

What is the issue with this LangServe class?

class MultiplyAPI:
    def multiply(self, input):
        return input * 2

AThe input parameter should be named data instead of input

BThe class is missing an __init__ method

CThe method name should be __call__, not multiply

DThe return statement should use input + 2 instead of input * 2

Step-by-Step Solution

Solution:

Step 1: Recall LangServe API method requirements
LangServe expects the API class to implement the __call__ method to process requests.
Step 2: Identify the problem
The class defines a method named multiply instead of __call__, so LangServe won't invoke it.
Final Answer:
The method name should be __call__, not multiply -> Option C
Quick Check:
Method must be named __call__ for LangServe to work [OK]

Quick Trick: Method must be __call__ for LangServe API classes [OK]

Common Mistakes:

MISTAKES

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