Updating array of objects in mongoose based off key in objects value

you want to using $push and $set in one findByIdAndUpdate, that's impossible, I prefer use findById() and process and save() so just try

exports.makePicks = async (req, res, next) => {  const picks = req.body;  try {    //implementation business logic    let result = await User.findById(req.user._id)    if(result.picks && result.picks.length > 0){      result.picks.forEach(item =>{        if([`week-${req.params.week}`] in item){          item[`week-${req.params.week}`] = picks        }        else{          result.picks.push({ [`week-${req.params.week}`] : picks })        }      })    }    else{      result.picks.push({ [`week-${req.params.week}`] : picks })    }    await result.save()    res.redirect('/api/dashboard');  } catch (error) {    console.log(error)  }}

note: don't use callback and async/await together

exports.makePicks = async (req, res, next) => {  const picks = req.body;  const { week } = req.params;  try {       let result = await User.findById(req.user._id);    const data = { [`week-${week}`]: picks };    const allPicks = [...result.picks];        if (allPicks.length > 0) {      // Search index of peek      const pickIndex = _.findIndex(allPicks, (pick) => {        return Object.keys(pick)[0] == `week-${week}`;      });      // If found, update it      if (pickIndex !== -1) {        console.log(chalk.green("true"));        allPicks[pickIndex] = data;      }      // Otherwise, push new pick      else {        console.log(chalk.red("false"));        allPicks.push(data);      }    } else {      allPicks.push(data);      console.log(chalk.yellow('results.picks is empty'))    }    result.picks = allPicks;    console.log('allPicks', allPicks);        await result.save();    res.redirect("/api/dashboard");  } catch (error) {    console.log(error);  }};