likes.js

// pg DB connection from config file /helpers/db.js
const db = require('../helpers/db.js')

exports.addLike = async function addLike(articleId, userId) {
            let sql = 'INSERT INTO likes (article_id, user_id) \
            SELECT articles.id, users.id \
            FROM (SELECT id FROM articles WHERE id='+articleId+') articles \
               , (SELECT id FROM users WHERE id='+userId+') users;'
            var obj = await db.query(sql)
            .then(obj => {
                return obj;
            });
    return obj;
}

exports.checkLike = async function checkLike(articleId,userId) {
    let sql = 'SELECT user_id,article_id FROM likes WHERE (article_id='+articleId+') AND user_id='+userId+';'; 
    var obj = await db.query(sql)
    .then(obj => {
        return obj;
    });
return obj;
}

// temp function to check user exists (later if is logged)

exports.checkUser = async function checkUser(userId) {
    let sql = 'SELECT id FROM users WHERE id='+userId+';'; 
    var obj = await db.query(sql)
    .then(obj => {
        return obj;
    });
return obj;
}

exports.removeLike = async function removeLike(articleId, userId) {
    let sql = 'DELETE FROM likes WHERE article_id='+articleId+' AND user_id='+userId+' RETURNING true;'
    var obj = await db.query(sql)
    .then(obj => {
        return obj;
    });
return obj;
}