如何在节点和快递中使用导出的 api 端点

Question

I am trying to get a better understanding of express and how it uses different end points.

I saw an example of an endpoint which reads in a json file being used like this.

const fs = require('fs');
const path = require('path');

export default app => {
  app.get('/api/price', (req, res) => {
    fs.readFile(path.resolve(__dirname, './price.json'), (err, resp) => {
      if (err) {
        res.send(400, 'ERROR');
      }

      res.send(resp);
    });
  });
};

it is then imported in a server.js file like the following. As you can see it is imported as price api.

import express from 'express';
import priceApi from './priceapi';
const app = express();

priceApi(app)

app.listen(3000, () => {
  console.log("Listening on PORT 3000");
});

My question is how do I use this priceApi so in particular `priceApi(app)and access the information stored in the JSON file and output information from the JSON file that the endpoint it is referring to in server.js?

Answer 1

In order to not having to load the file on every request, load the json file once during startup of your app. Then expose a new endpoint and serve the json:

import express from 'express';
import priceApi from './priceapi';
const app = express();
const prices = require('./path/to/prices.json');

app.get('/api/price', (req,res) => {
  res.json(prices); // does not necessarily need to be this, you can also map/filter stuff of the prices-json and only return this data
});

app.listen(3000, () => {
  console.log("Listening on PORT 3000");
});