Question

0

65

Views

Missing updated record when using map function

This is my code for update many records with mongodb.

const nfts = await waxModel.find();
console.log(nfts.length) // -> 121

// Option 1: using map()
nfts.map(async nft => {
    nft.trait_attribute = null;
    await nft.save();
  });

// Option 2: using loop
for (let i = 0; i < nfts.length; i++) {
    nfts[i].trait_attribute = null;
    await nfts[i].save();
  }

This is my DB, no recored have trait_attribute: null:

This is the first result when I use map(), only have 2 records:

And this is the second result when I use for loop:

I don't know that is the problem. In my previous question: I know map methods don't handle the asynchronous function but it's still have full records not missing many updated records as now. Thank for your attention.

8 months ago · Juan Pablo Isaza

1 answers

Answer question

0

Answer question

Find remote jobs

Answer 1 · 2022-06-25T19:57:40.153Z

It looks like your code doesn't handle race conditions well.

The first option saves every nft simultaneously whilst the second one saves them one at a time. A more readable way to do that would be using a for-of loop:

for (const nft of nfts) {
  nft.trait_attribute = null;
  await nft.save();
}