Why Is My React App Not Displaying POST Response from FastAPI?

React Not Displaying POST Response from FastAPI Backend

In React-based applications, issues can arise when fetching data from a FastAPI backend and displaying it on the user interface. A common problem is that data is not shown on the front-end, despite being successfully retrieved from the server.

To resolve this issue, you need to enable Cross-Origin Resource Sharing (CORS) in your FastAPI application. CORS allows requests from different origins (e.g., your React application's domain) to interact with the backend server.

Solution:

Configure CORS middleware in your FastAPI app to allow cross-origin requests. The CORSMiddleware class in FastAPI can be used to set up CORS headers. Here's an example:

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

app = FastAPI()

# Set allowed origins (e.g., your React application's domain)
origins = ["http://localhost:3000"]

app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

This configuration permits requests from specified origins, enabling your React application to access data from the backend server.

Additional Information:

• Understand the concept of origins: A unique combination of protocol, domain, and port.
• Refer to the FastAPI documentation for more details on CORS middleware.
• Ensure that the code you provided to fetch and display data from the backend is functioning correctly.

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