Query datevalue of a inner Array element - mongodb

Question

Need help with some MongoDB query:
The document I have is below and I am trying to search based on 2 conditions
The meta.tags.code = "ABC"
Its LastSyncDateTime should
meta.extension.value == "" (OR)
the meta.extension.value is less than meta.lastUpdated
Data :
{
"meta" : {
"extension" : [
{
"url" : "LastSyncDateTime",
"value" : "20190206-00:49:25.694"
},
{
"url" : "RetryCount",
"value" : "0"
}
],
"lastUpdate" : "20190207-01:21:41.095",
"tags" : [
{
"code" : "ABC",
"system" : "type"
},
{
"code" : "XYZ",
"system" : "SourceSystem"
}
]
}
}
Query:
db.proc_patients_service.find({
"meta.tags.code": "ABC",
$or: [{
"meta.extension.value": ""
}, {
$expr: { "$lt": [{ "mgfunc": "ISODate", "params": [{ "$arrayElemAt": ["$meta.extension.value", 0] }] }, { "mgfunc": "ISODate", "params": ["$meta.lastUpdate"] }] }
}]
})
But it is only fetching ABC Patients whose LastSyncDateTime is empty and ignores the other condition.

Answer 1

Using MongoDB Aggregation, I have converted your string to date with operator $dateFromString and then compare the value as per your criteria.
db.proc_patients_service.aggregate([
{ $match: { "meta.tags.code": "ABC", } },
{ $unwind: "$meta.extension" },
{
$project: {
'meta.tags': '$meta.tags',
'meta.lastUpdate': { '$dateFromString': { 'dateString': '$meta.lastUpdate', format: "%Y%m%d-%H:%M:%S.%L" } },
'meta.extension.url': '$meta.extension.url',
'meta.extension.value': {
$cond: {
if: { $ne: ["$meta.extension.value", "0"] }, then: { '$dateFromString': { 'dateString': '$meta.extension.value', format: "%Y%m%d-%H:%M:%S.%L" } }, else: 0
}
}
}
},
{
$match: {
$or: [
{ "meta.extension.value": 0 },
{ $expr: { $lt: ["$meta.extension.value", "$meta.lastUpdate"] } }
]
}
},
{
$group: { _id: '_id', 'extension': { $push: '$meta.extension' }, "lastUpdate": { $first: '$meta.lastUpdate' }, 'tags': { $first: '$meta.tags' } }
},
{
$project: { meta: { 'extension': '$extension', lastUpdate: '$lastUpdate', 'tags': '$tags' } }
}
])