Express CRUD operations "Cannot read properties of undefined (reading 'comment')"

Question

I am building a simple app that displays an index of comments, allows posting of new comments, and editing+deleting of existing comments. I do this following Colt Steele's course section 371.

At a certain point, my code no longer recognizes the object I reference. Then it recognizes it again randomly. I am not sure where my problem is.

Index.js:

    const express = require('express')
    const path = require('path')
    const methodOverride = require('method-override')
    const app = express();
    const { v4: uuid } = require('uuid'); //For generating ID's
 
 
    app.set('view engine', 'ejs')
    app.set('views', path.join(__dirname, 'views'))
    app.use(express.urlencoded({ extended: true }))
    app.use(express.json())
    app.use(methodOverride('_method'))
 
 
 
    let comments = [
        {
            username: 'External_Mall_3897',
            comment: 'that Kana"s death stare when she sees Aqua princess carry Akane 😂',
            score: 564,
            id: uuid()
 
        },
        {
            username: 'Acrzyguy',
            comment: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
            score: 304,
            id: uuid()
        },
        {
            username: 'mr_miscellaneous123',
            comment: 'How on earth did Aqua keep up that kind of acting for all the performances?',
            score: 461,
            id: uuid()
        },

    ]
 
    app.get('/comments', (req, res) => {
        res.render('index', { comments })
    })
 
    app.get('/comments/new', (req, res) => {
        res.render('new')
    })
    app.post('/comments', (req, res) => {
        const { username, comment } = req.body;
        comments.push({ username, comment, score: 0, id: uuid() })
        res.redirect('/comments')
    })
 
    app.get('/comments/:id', (req, res) => {
        const { id } = req.params;
        const comment = comments.find(c => c.id === id);
        res.render('show', { comment })
    })
    app.get('/comments/:id/edit', (req, res) => {
        const { id } = req.params;
        const comment = comments.find(c => c.id === id);
        res.render('edit', { comment })
    })
    app.patch('/comments/:id/', () => {
        const { id } = req.params;
        const foundComment = comments.find(c => c.id === id)
        const newCommentText = req.body.comment
        foundComment.comment = newCommentText;
        res.redirect('/comments')
        })
 
        app.listen(3030, () => {
        console.log('listening on 3030')
        })





index.ejs: https://pastebin.com/rLr4HHDT
 
new.ejs: https://pastebin.com/Dw1WRjx1
 
show.ejs: https://pastebin.com/9SeEKEjy
 
edit.ejs: https://pastebin.com/j0HpFLpJ

Mureinik · Accepted Answer · 2024-09-01 15:12:08Z

0

It looks like you're trying to reference a comment with an id that doesn't exist. You should probably check for that and explicitly handle it:

app.patch('/comments/:id/', () => {
    const { id } = req.params;
    const foundComment = comments.find(c => c.id === id)

    // If the comment isn't found, return a 404
    if (!foundComment)
        res.status(404).end(`No comment found with id=${id}`)
        return
    }

    // If the comment is found, update it
    const newCommentText = req.body.comment
    foundComment.comment = newCommentText;
    res.redirect('/comments')
})

answered Sep 1, 2024 at 15:12

Mureinik

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