I am trying to compare the price between the first and last element inside a nested array.
The following is a part of my data:
priceRange:[
[1600732800000,5.28424438726287],
[1600819200000,5.08434522342211],
[1600905600000,3.491229168216385],
[1600992000000,4.573890580327729],
[1601078400000,4.702973876095848]
]
So in essence I want to know if the second element inside the first array (5.28424438726287) is bigger than the second element inside the last array (4.702973876095848)
I have hard time selecting the last array inside the nested array: The folowing didn't work:
$expr: { $gt: [{ $last: "$priceRange" }, 0.000001] }
I can select the first element:
priceRange.0.1
And then there is the question how do you compare them while also having other filter constraints?
{name: "Some stock", comparing the prices}
You can add this aggregation stage:
This query create a fields called isBigger where compare the values you want:
And the output will be true or false if is bigger the number or not.
db.collection.aggregate([
{
"$project": {
"isBigger": {
"$cond": {
"if": {
"$gt": [
{
"$last": {
"$first": "$priceRange"
}
},
{
"$last": {
"$last": "$priceRange"
}
}
]
},
"then": true,
"else": false
}
}
}
}
])
Example here