Missing updated record when using map function

user_15319198 0
Viewed 47

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:

enter image description here

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

enter image description here

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

enter image description here

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.

node.js mongodb asynchronous javascript
1 Answers

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();
}
user_83849100
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