mongodb aggregation $in with $type - mongodb

Question

I have a collection:
{
values: [null, null, 1, 2, 3, 4.6],
}
I want to receive a property which tells me if any of those values is a number.
I've tried:
{
$project: {
hasNumber: {
$in: [{ $eq: [{ $type: '$$CURRENT' }, 'number'] }, '$values'],
},
},
}
but it doesn't work, is something like this possible with aggregations?

Answer 1

Please try this :
db.yourCollectionName.aggregate([{
$project: {
values: 1, hasNumber: {
$gt: [{
$size: {
$filter:
{
input: "$values",
as: "value",
cond: { $eq: [{ $type: '$$value' }, 'int'] }
// To check & include double as well, replace above cond with this :
//cond: { $or :[ {$eq: [{ $type: '$$value' }, 'int']} , {$eq: [{ $type: '$$value' }, 'double']}] }
}
}
}, 0]
}
}
}])
Collection Data :
/* 1 */
{
"_id" : ObjectId("5e14d9dd627ef78236ea77e3"),
"values" : [
null,
null,
1,
2,
3,
4.6
]
}
/* 2 */
{
"_id" : ObjectId("5e14d9e4627ef78236ea785f"),
"values" : [
null,
null
]
}
/* 3 */
{
"_id" : ObjectId("5e14decc627ef78236eb12d3"),
"values" : [
"1",
4.6
]
}
Result :
/* 1 */
{
"_id" : ObjectId("5e14d9dd627ef78236ea77e3"),
"values" : [
null,
null,
1,
2,
3,
4.6
],
"hasNumber" : true
}
/* 2 */
{
"_id" : ObjectId("5e14d9e4627ef78236ea785f"),
"values" : [
null,
null
],
"hasNumber" : false
}
/* 3 */ // If we're checking for double this hasNumber will be true
{
"_id" : ObjectId("5e14decc627ef78236eb12d3"),
"values" : [
"1",
4.6
],
"hasNumber" : false
}

Answer 2

Debugging your code...
$in: [{ $eq: [{ $type: '$$CURRENT' }, 'number'] }, '$values'],
You are checking if false is inside $values.
Explanation:
'$$CURRENT' returns raw document
{ $type: '$$CURRENT' } returns 'object'
$eq:['object', 'number'] will always return false
$in:[ 'false', '$values'] will be false
I've solved with $convert operator
db.collection.aggregate([
{
$project: {
hasNumber: {
$cond: [
{
$eq: [
{
$map: {
input: "$values",
in: {
$convert: {
input: "$$this",
to: "int",
onError: -999,
onNull: -999
}
}
}
},
"$values"
]
},
true,
false
]
}
}
}
])