[nodebb-plugin-autothumb] How can I associate the topic to the thumbnail

[busker]

I want to make a plugin that works as below.

1. The topic content has an image markdown tag and extracts the first image path found.
2. If the user has not attached a thumbnail to the topic, download the above image path.
3. Set the downloaded image as a thumbnail for the topic, and save the image in the thumbnail file path.
4. The thumbnail is shown to the user when showing nodebb topics.

Please advise me on how to handle step 3.

It's the source I've worked on so far
library.js

'use strict';

const axios = require('axios');
const fs = require('fs');
const path = require('path');
const os = require('os');
const { mkdirSync } = require('fs');
const topics = require.main.require('./src/topics');
const plugin = module.exports;

var IMAGE_DIR = '/tmp/nodebb-images'

plugin.init = async function (params) {
    //const { router /* , middleware , controllers */ } = params;
    IMAGE_DIR = await path.join(os.tmpdir(), 'nodebb-images');

    const hasImgDir = await fs.existsSync(IMAGE_DIR);
    if (!hasImgDir) {
        await mkdirSync(IMAGE_DIR);
    }
};

plugin.onTopicCreate = async function(hookData) {
    //await console.log("----------------------------- onTopicCreate -----------------------------------");
    //console.log(hookData);
    await setTopicThumbnail(hookData.topic.tid, hookData.data.content);
    return hookData;
};

plugin.onTopicEdit = async function(hookData) {
    await console.log("----------------------------- setTopicThumbnail -----------------------------------");
    console.log(hookData);
    await setTopicThumbnail(hookData.topic.tid, hookData.data.content);
    return hookData;
};

async function setTopicThumbnail(tid, content) {
    const imageUrl = extractImageUrl(content);
    if (!imageUrl) {
        //await console.log("Image URL Not found in markdown content");
        return;
    }

    if (!imageUrl.startsWith('http')) {
        return;
    }

    try {
        const imagePath = await downloadFile(imageUrl, tid);
        await topics.setThumbnail(tid, imagePath);
    } catch (err) {
        console.error('Error cound not download image:', err);
    }
};

async function downloadFile(url, tid) {
    try {
        const response = await axios({
            method: 'get',
            url: url,
            responseType: 'stream'
        });

        const ext = path.extname(url);
        const fileName = `${tid}${ext}`;
        const filePath = path.join(IMAGE_DIR, fileName);

        return new Promise((resolve, reject) => {
            const writer = fs.createWriteStream(filePath);

            response.data.pipe(writer);

            writer.on('finish', () => resolve(filePath));
            writer.on('error', reject);
        });
    } catch (err) {
        throw new Error('이미지 다운로드 실패: ' + err.message);
    }
};

function extractImageUrl(content) {
    const regex = /!\[.*?\]\((.*?)\)/;
    const match = content.match(regex);
    return match ? match[1] : null;
};

plugin.json

{
    "id": "nodebb-plugin-autothumb",
    "name": "Auto Image Thumbnail Plugin",
    "version": "0.1.0",
    "description": "Automatically sets the first image in a post as the topic thumbnail.",
    "library": "./library.js",
    "license": "MIT",
    "hooks": [
        { "hook": "static:app.load", "method": "init" },
        { "hook": "filter:topic.create", "method": "onTopicCreate" },
        { "hook": "filter:topic.edit", "method": "onTopicEdit" }
    ],
    "dependencies": {
        "axios": "^0.21.1"
    }
}

[julian]

For what it's worth, I think this is a nice feature and should be something we do in core.

[busker]

Thank you very much for your positive feedback.

[julian]

@busker this is now on-track to be included in NodeBB v4.

feat: append uploaded images into thumbnail set · NodeBB/NodeBB@cc65214

Node.js based forum software built for the modern web - feat: append uploaded images into thumbnail set · NodeBB/NodeBB@cc65214

GitHub (github.com)

Uploaded images are now automatically added to the thumbnail set.

[busker]

Thank you for your hard work.

I was touched that the nodebb community accepts users' needs quickly and positively, and reflects them immediately.

Thanks once again.

[julian]

@busker Keep in mind that this encompasses uploaded media only. Externally linked media is excluded (so, giphy embeds would be an example that would not be included).

Edit: filter:topics.hasThumbs has been added (in addition to already-added filter:topics.getThumbs) so that plugins can append images to the thumbnail list.