This will return docs where field1 is greater that field2
collection.find( { $expr: { $gt: [ "$field1" , "$field2" ] } } )
I want to get documents where difference between field1 and field2 is greater or less than 20. Can that be done?
something like this.
{
match: {
$expr: {
{
$expr: {
$gt: [
$subtract: ["$field1", "$field2"], 20
]
}
}
}
}
}
not looking for an aggregation solution
Yes, you can just use a similar query to what you're already doing, you just have to check both ways field1 - field2 > 20 or field2 - field1 > 20.
You can easily achieve this using $abs (absolute(field1 - field2) > 20), like so:
db.collection.find({
$expr: {
$gt: [
{
$abs: {
$subtract: [
"$field1",
"$field2"
]
}
},
20
]
}
})