MongoDB Node findone how to handle no results?
node.jsMongodbnode.js Problem Overview
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..)
node.js Solutions
Solution 1 - node.js
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
}
}
Solution 2 - node.js
All of these answers below are outdated. findOne is deprecated. Lastest 2.1 documentation proposes to use
find(query).limit(1).next(function(err, doc){
// handle data
})
Solution 3 - node.js
Simply as:
collection.findOne({query}, function(err, result) {
if (!result) {
// Resolve your query here
}
}
Solution 4 - node.js
nowadays - since node 8 - you can do this inside an async function:
async function func() {
try {
const result = await db.collection('xxx').findOne({query});
if (!result) {
// no result
} else {
// do something with result
}
} catch (err) {
// error occured
}
}
Solution 5 - node.js
If result is null then mongo didn't find a document matching your query. Have tried the query from the mongo shell?
Solution 6 - node.js
collection.findOne({query}, function(err, result) {
if (err) { /* handle err */ }
if (result.length === 0) {
// we don't have result
}
}