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Im using the npm mongodb driver with node.
I have
collection.findOne({query}, function(err, result) { //do something } The problem is say I dont have any results, err is still null whether I find a result or don't. How would I know that there were no results found with the query?
I've also tried
info = collection.findOne(.... But the info is just undefined (it looked asynchronous so I didn't think it was the way to go anyway..)
608
findOne done not return cursor but single document. "Find" returns cursor. In case "findOne({"query"}) " is not able to fins any matched document then it returns "null".
The findOne() method finds and returns one document that matches the given selection criteria. If multiple documents satisfy the given query expression, then this method will return the first document according to the natural order which reflects the order of documents on the disk.
MongoDB findOne() method returns only one document that satisfies the criteria entered. If the criteria entered matches for more than one document, the method returns only one document according to natural ordering, which reflects the order in which the documents are stored in the database.
Another way is to get Promise in findOne , as this doc said, . exec() gives you a fully-fledged promise. Even with Promise , to meet you requirement, the result could be returned through callback function.
Not finding any records isn't an error condition, so what you want to look for is the lack of a value in result. Since any matching documents will always be "truthy", you can simply use a simple if (result) check. E.g.,
collection.findOne({query}, function(err, result) { if (err) { /* handle err */ } if (result) { // we have a result } else { // we don't } } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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