Date operation insede and array (aggreagation) - node.js

Question

I want to build online test application using mongoDB and nodeJS. And there is a feature which admin can view user test history (with date filter option).
How to do the query, if I want to display only user which the test results array contains date specified by admin.
The date filter will be based on day, month, year from scheduledAt.startTime, and I think I must use aggregate framework to achieve this.
Let's say I have users document like below:
{
"_id" : ObjectId("582a7b315c57b9164cac3295"),
"username" : "lalalala#gmail.com",
"displayName" : "lalala",
"testResults" : [
{
"applyAs" : [
"finance"
],
"scheduledAt" : {
"endTime" : ISODate("2016-11-15T16:00:00.000Z"),
"startTime" : ISODate("2016-11-15T01:00:00.000Z")
},
"results" : [
ObjectId("582a7b3e5c57b9164cac3299"),
ObjectId("582a7cc25c57b9164cac329d")
],
"_id" : ObjectId("582a7b3e5c57b9164cac3296")
},
{
.....
}
],
"password" : "andi",
}
testResults document:
{
"_id" : ObjectId("582a7cc25c57b9164cac329d"),
"testCategory" : "english",
"testVersion" : "EAX",
"testTakenTime" : ISODate("2016-11-15T03:10:58.623Z"),
"score" : 2,
"userAnswer" : [
{
"answer" : 1,
"problemId" : ObjectId("581ff74002bb1218f87f3fab")
},
{
"answer" : 0,
"problemId" : ObjectId("581ff78202bb1218f87f3fac")
},
{
"answer" : 0,
"problemId" : ObjectId("581ff7ca02bb1218f87f3fad")
}
],
"__v" : 0
}
What I have tried until now is like below. If I want to count total document, which part of my aggregation framework should I change. Because in query below, totalData is being summed per group not per whole returned document.
User
.aggregate([
{
$unwind: '$testResults'
},
{
$project: {
'_id': 1,
'displayName': 1,
'testResults': 1,
'dayOfTest': { $dayOfMonth: '$testResults.scheduledAt.startTime' },
'monthOfTest': { $month: '$testResults.scheduledAt.startTime' },
'yearOfTest': { $year: '$testResults.scheduledAt.startTime' }
}
},
{
$match: {
dayOfTest: date.getDate(),
monthOfTest: date.getMonth() + 1,
yearOfTest: date.getFullYear()
}
},
{
$group: {
_id: {id: '$_id', displayName: '$displayName'},
testResults: {
$push: '$testResults'
},
totalData: {
$sum: 1
}
}
},
])
.then(function(result) {
res.send(result);
})
.catch(function(err) {
console.error(err);
next(err);
});

Answer 1

You can try something like this. Added the project stage to keep the test results if any of result element matches on the date passed. Add this as the first step in the pipeline and you can add the grouping stage the way you want.
$map applies an equals comparison between the date passed and start date in each test result element and generates an array with true and false values. $anyElementTrue inspects this array and returns true only if there is atleast one true value in the array. Match stage to include only elements with matched value of true.
aggregate([{
"$project": {
"_id": 1,
"displayName":1,
"testResults": 1,
"matched": {
"$anyElementTrue": {
"$map": {
"input": "$testResults",
"as": "result",
"in": {
"$eq": [{ $dateToString: { format: "%Y-%m-%d", date: '$$result.scheduledAt.startTime' } }, '2016-11-15']
}
}
}
}
}
}, {
"$match": {
"matched": true
}
}])
Alternative Version:
Similar to the above version but this one combines both the project and match stage into one. The $cond with $redact accounts for match and when match is found it keeps the complete tree or else discards it.
aggregate([{
"$redact": {
"$cond": [{
"$anyElementTrue": {
"$map": {
"input": "$testResults",
"as": "result",
"in": {
"$eq": [{
$dateToString: {
format: "%Y-%m-%d",
date: '$$result.scheduledAt.startTime'
}
}, '2016-11-15']
}
}
}
},
"$$KEEP",
"$$PRUNE"
]
}
}])