CODEWITHSUNDEEP
javascriptnode.jsmongodbmongoosesave
Queryzi
Queryzi

Reputation: 15

(node:50868) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'save' of null

So I am trying to make a simple level-XP system in discord where it would level up every time someone sends a message. I have this for my level system in my message event. Level is defined as the schema of it as I am using Mongoose. There problem is it can save it the person has no data and they send a message it creates data like XP: 0 level: 1 but afterwards won't update again when they send a message to like say XP: 25 etc. The error is (node:50868) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'save' of null

level1.findOne({ guildID: message.guild.id, userID: message.author.id }, async (err, res) => {
  if(err) return console.error(err)

  if(!res) {
    let newdata = new level1({
      guildID: message.guild.id,
      userID: message.author.id,
      level: 1,
      xp: 0,
      totalxp: 0,
      time: Date.now()
    })

    newdata.save()
    res = newdata
  } else {

    if (message.content.startsWith(`${prefix}`)) return;

  const generate = Math.floor(Math.random() * 18);
    (await level1.findOneAndUpdate({ guildID: message.guild.id, userID: message.guild.id }, { totalxp: res.totalxp += generate, xp: res.xp + generate, time: Date.now() })).save()

  if(res.xp >= res.level * 300) {
    (await level1.findOneAndUpdate({ guildID: message.guild.id, userID: message.guild.id }, { level: res.level++, xp: 0 })).save()
    message.channel.send(`Congratulations you are now Level **${res.level}**, ${message.author}`);
  }
}

})

Upvotes: 0

Views: 686

Answers (1)

Mohammed Yousry
Mohammed Yousry

Reputation: 2184

you don't need to add .save() to findOneAndUpdate

findOneAndUpdate will update the record in db without the need of using .save()

so your update queries should be like 

await level1.findOneAndUpdate(
    { guildID: message.guild.id, userID: message.guild.id }, // filter part
    { totalxp: res.totalxp += generate, xp: res.xp + generate, time: Date.now() } // update part
)

and 

await level1.findOneAndUpdate(
    { guildID: message.guild.id, userID: message.guild.id },
    { level: res.level++, xp: 0 }
)

I think this could do the trick

regarding the logic of the code, I think we can combine both the update queries in one query using some logic before the update query

we can use this logic in the else part

const generate = Math.floor(Math.random() * 18);

let updatePart = {
    totalxp: (res.totalxp || 0) + generate, // this will be updated in all cases, even if the level is upgraded or not
    time: Date.now() // this will also be updated in all cases
}

let msg = ''; // a message to be returned after the update

if (res.xp + generate >= res.level * 300) {
    // if experience + random generate is greater than level * 300, 
    // then we need to update the level, and set the xp to 0

    updatePart.level = res.level++;
    updatePart.xp = 0;

    // update the msg with the new level
    msg = `Congratulations you are now Level **${res.level++}**, ${message.author}`

} else {
    // if experience + random generate is lower than level * 300, this means the level is the same
    // then we need to update the xp only
    updatePart.xp = res.xp + generate;

    // update the msg
    msg = `Experience updated successfully`
}

// just do the update query once, 
// If we just need to update the document, 
// we can use updateOne instead of findOneAndUpdate

await level1.updateOne( // you can use findOneAndUpdate also, it's okay
    { guildID: message.guild.id, userID: message.guild.id }, // filter part
    updatePart // this is the update object
)

message.channel.send(msg);

hope it helps

Upvotes: 2

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