猫鼬增量值不起作用

Question

I am trying to increment a value and assign it back to the key.

const TopicSchema = mongoose.Schema({
    count: Number
});

topic.count += 2

Instead of 4, 22 returned. If I do it a couple of times, it is always appending 2 to the end like 2222 .

What's wrong?

Answer 1

Sounds like you are concatenating strings instead of adding numbers. Try wrapping topic.count in Number( )

Answer 2

If you'are trying to update the document you better use $inc operator provided by mongodb . Read more about it here .

By the way, this is how you can get it done in a single query

db.topic.update(
{ }, //your filter here
{ $inc: { count: 2} }
 )