單擊前端的按鈕后，我想執行一個需要 10 到 30 秒才能運行的 python 腳本。
我試圖在我的后路由/控制器中呼叫 python 腳本，但出現以下錯誤：
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
在腳本運行之前，我不想向客戶端發送任何內容。
路由/控制器：
const express = require("express");
const router = express.Router();
router.post("/solve", async function (req, res) {
const board = JSON.stringify({
board: req.body.grid,
});
const spawn = require("child_process").spawn;
const pythonProcess = spawn("python", ["./crossword/crossword.py", board]);
pythonProcess.stdout.on("data", (data) => {
// Do something with the data returned from python script
solved_data = JSON.parse(data.toString());
res.send(JSON.stringify(solved_data));
});
});
uj5u.com熱心網友回復：
之所以顯示該錯誤，是因為您正在發送資料的data事件中，python 腳本在每次輸出更改時不斷觸發，該腳本反復向客戶端發送回應（這不好），要解決該問題，您應該只發送一次回應，為此您應該訂閱行程的退出事件，以便收集所有輸出，然后在行程關閉時將輸出作為回應發送
const express = require("express");
const router = express.Router();
let data = '';
router.post("/solve", async function (req, res) {
const board = JSON.stringify({
board: req.body.grid,
});
const spawn = require("child_process").spawn;
const pythonProcess = spawn("python", ["./crossword/crossword.py", board]);
pythonProcess.stdout.on("data", (response) => {
// Keep collecting the data from python script
data = response;
});
pythonProcess.on('exit', function(code, signal) {
console.log('Python process is now completed send data as response');
let solved_data = JSON.parse(data);
res.send(JSON.stringify(solved_data));
//you can also check code to verify if exit was due to error or normal
});
});
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