无法从获取请求 Node.js、Express 中获取对象

Question

I'm following Traversy Media's Node.js tutorial and have run into an issue i'm unable to solve. I'm trying to get the response of one object from an array of objects with the code:

app.get('/api/members/:id', (req, res) => {
  res.json(members.filter(member => member.id === parseInt(req.params.id)));
});

but using postman (or typing this into my browser) when I try to get http://localhost:5000/api/members/1 it gives me an empty array.

This is my main JavaScript file:

const express = require('express');
const path = require('path');
const app = express();
const logger = require('./middleware/logger')

const members = require('./Members')

//init middleware
//app.use(logger);

//Gets all members

app.get('/api/members', (req, res) => res.json(members));

//Get Single Members
app.get('/api/members/:id', (req, res) => {
  res.json(members.filter(member => member.id === parseInt(req.params.id)));
});
//Set a static folder
app.use(express.static(path.join(__dirname, 'public')));

const PORT = process.env.PORT || 5000;

app.listen(PORT, () => console.log(`Server started on port ${PORT}`));

And this is the Members.js file

const members = [
    {
      name:"john",
      email:"john@mail.com",
      status: "active"
    },
    {
      name:"sally",
      email:"sally@mail.com",
      status: "inactive"
    },
    {
      name:"josh",
      email:"josh@mail.com",
      status: "active"
    }
];

module.exports = members;

I'm totally stuck and any help is very appreciated.

Answer 1

The objects in your array have no 'id' field, which is why nothing is being matched with the filter.

What you're saying is: 'Find the object in this array, which has an 'id' field of X', where X is req.params.id. This is not matching anything because your objects only have 'name', 'email', and 'status' fields, ie there is no 'id' field, hence nothing is being matched when you call the filter method.

This should become clear if you do a little test..

Replace this

app.get('/api/members/:id', (req, res) => {
  res.json(members.filter(member => member.id === parseInt(req.params.id)));
});

With this

app.get('/api/members/:email', (req, res) => {
  res.json(members.filter(member => member.email === req.params.email));
});

And when you're sending the request, send up 'josh@mail.com' as the request parameter, you should find that this record is returned:

http://localhost:5000/api/members/josh@mail.com

    {
      name:"josh",
      email:"josh@mail.com",
      status: "active"
    }

This happens because your objects have an email field, and you're matching against that, and there IS an object who's email field has a value of 'josh@mail.com'.

So to reiterate, your current code is not working because you're trying to match your objects with a given 'id' field, but they do not contain an 'id' field.

If you changed your data structure to be something like

    {
      id: 1, // Added 'id' field
      name:"josh",
      email:"josh@mail.com",
      status: "active"
    }

Then you'd have something to match against, in that example, if you sent '1' up as the id, then your code should match that document.

Hope that makes sense and is of some use.