Rows whose field is twice that of the other field explain with example :
{id : 1 , price : 10 , spent : 5} {id : 1 , price : 20 , spent : 30} {id : 1 , price : 40 , spent : 90} {id : 1 , price : 80 , spent : 200}
I want row that spend is equal or bigger twice price (spent >= 2*price)
result :
{id : 1 , price : 40 , spent : 90}
==> (spent >= 2price) [90>80]*
{id : 1 , price : 80 , spent : 200}
==> (spent >= 2price) [160>200]*
please refer suggestion except use $where
my mongo cluster have limitations of use $where
(MongoError: $where is not allowed in this atlas tier)
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Answer
MongoDB documentation is very good with examples.
There is a place Reference
that has all the operators.
If you haven’t found it, maybe try the bellow, i think this is what you need.
Query
- we can refer to the field with
$fieldName
- and gt/multiply operators are used
- finally
$expr
is used in match when we use aggregate operators (instead of query operaros) like we did here
aggregate( [{"$match": {"$expr": {"$gt": ["$spent", {"$multiply": [2, "$price"]}]}}}])