【Node.js】CSVファイルをダウンロードするAPIを構築

package.jsonを作成

npm init -y

必要なパッケージをimport

npm install express csv-writer

npm install --save-dev typescript @types/node @types/express ts-node

tsconfig.jsonの作成

tsconfig.json

{
	"compilerOptions": {
	  "target": "ES6",
	  "module": "commonjs",
	  "outDir": "./dist",
	  "rootDir": "./src",
	  "strict": true,
	  "esModuleInterop": true
	}
  }

サーバーファイルを作成

src/index.ts

import express from "express";
import { createObjectCsvWriter } from "csv-writer";
import path from "path";
import fs from "fs";

const app = express();
const port = 3100;

app.get("/download-csv", async (req, res) => {
  try {
    const csvFilePath = path.join(__dirname, "output.csv");
    const csvWriter = createObjectCsvWriter({
      path: csvFilePath,
      header: [
        { id: "id", title: "ID" },
        { id: "name", title: "Name" },
        { id: "email", title: "Email" },
      ],
    });

    const records = [
      { id: 1, name: "John Doe", email: "[e-mail]" },
      { id: 2, name: "Jane Doe", email: "[e-mail]" },
    ];

    await csvWriter.writeRecords(records);

    res.download(csvFilePath, "output.csv", (err) => {
      if (err) {
        console.error("Error downloading the file:", err);
        res.status(500).send("Error downloading the file");
      } else {
        fs.unlinkSync(csvFilePath); // ダウンロード後にファイルを削除
      }
    });
  } catch (error) {
    console.error("Error processing the request:", error);
    res.status(503).send("Service Unavailable");
  }
});

app.listen(port, () => {
  console.log(`Server is running at http://localhost:${port}`);
});

サーバ起動

npx ts-node src/index.ts