Parse Query by subfield/dot notation - parse-platform

Question

tl;dr
Can ParseCloud/MongoDB filter by Pointer<class>.filed ? By
Pointer<class>.Pointer<class> ? By existence of data in that filed?
Long question:
Round is object which will be played automatically when time will come.
Payment object which indicates that user made payment. When payment being spent we set field round to it.
Player which links online User with Payment
I need to query player for few conditions:
Player
online
has valid(no round and valid equal to 'valid') payment
Player
user equal to specific user
has no payment
Player
user equal to specific user
has valid(no round and valid equal to 'valid') payment
And I made everything to work except validating Payment inside Player query.
Here is condition 1 from the list.
var query = new Parse.Query(keys.Player);
query.skip(0);
query.limit(oneRoundMaxPlayers);
query.greaterThanOrEqualTo(keys.last_online_date, lastAllowedOnline);
// looks like no filter applied here
query.doesNotExist("payment.round");
query.exists(keys.payment);
// This line will make query return 0 elements
// query.equalTo("payment.valid", "valid");
query.include(keys.user);
query.include(keys.payment);
Here is 2 OR 3
var queryPaymentExists = new Parse.Query(keys.Player);
queryPaymentExists.skip(0);
queryPaymentExists.limit(1);
queryPaymentExists.exists(keys.payment);
//This line not filtering
queryPaymentExists.doesNotExist(keys.payment + "." + keys.round);
queryPaymentExists.equalTo(keys.user, user);
// This line makes query always return 0 elements
// queryPaymentExists.equalTo(keys.payment + "." + keys.valid, keys.payment_valid);
var queryPaymentDoesNotExist = new Parse.Query(keys.Player);
queryPaymentDoesNotExist.skip(0);
queryPaymentDoesNotExist.limit(1);
queryPaymentDoesNotExist.doesNotExist(keys.payment);
queryPaymentDoesNotExist.equalTo(keys.user, user);
var compoundQuery = Parse.Query.or(queryPaymentExists, queryPaymentDoesNotExist);
compoundQuery.include(keys.user);
compoundQuery.include(keys.payment);
compoundQuery.include(keys.payment + "." + keys.round);
I've checked logs from Mongo and they looks following
verbose: REQUEST for [GET] /classes/Player: {
"include": "user,payment,payment.round",
"where": {
"$or": [
{
"payment": {
"$exists": true
},
"payment.round": {
"$exists": false
},
"user": {
"__type": "Pointer",
"className": "_User",
"objectId": "ASPKs6UVwb"
}
},
{
"payment": {
"$exists": false
},
"user": {
"__type": "Pointer",
"className": "_User",
"objectId": "ASPKs6UVwb"
}
}
]
}
}
Here is response:
verbose: RESPONSE from [GET] /classes/Player: {
"response": {
"results": [
{
"objectId": "VHU9uwmLA7",
"last_online_date": {
"__type": "Date",
"iso": "2017-10-28T15:15:23.547Z"
},
"user": {
"objectId": "ASPKs6UVwb",
"username": "cn92Ekv5WPJcuHjkmTajmZMDW",
},
"createdAt": "2017-10-22T11:43:16.804Z",
"updatedAt": "2017-10-25T09:23:20.035Z",
"ACL": {
"*": {
"read": true
},
"ASPKs6UVwb": {
"read": true,
"write": true
}
},
"__type": "Object",
"className": "_User"
},
"createdAt": "2017-10-27T21:03:35.442Z",
"updatedAt": "2017-10-28T15:15:23.556Z",
"payment": {
"objectId": "nr7ln7U3eJ",
"payment_date": {
"__type": "Date",
"iso": "2017-10-27T23:42:50.614Z"
},
"user": {
"__type": "Pointer",
"className": "_User",
"objectId": "ASPKs6UVwb"
},
"createdAt": "2017-10-27T23:42:50.624Z",
"updatedAt": "2017-10-28T15:12:30.131Z",
"valid": "valid",
"round": {
"objectId": "jF9gqG4ndh",
"round_date": {
"__type": "Date",
"iso": "2017-10-28T15:12:00.027Z"
},
"createdAt": "2017-10-28T15:11:00.036Z",
"updatedAt": "2017-10-28T15:12:30.108Z",
,
"ACL": {
"*": {
"read": true
}
},
"__type": "Object",
"className": "Round"
},
"ACL": {
"ASPKs6UVwb": {
"read": true
}
},
"__type": "Object",
"className": "Payment"
},
"ACL": {
"ASPKs6UVwb": {
"read": true
}
}
}
]
}
}
You can see that response contains payment.round.
My question is following:
Can ParseCloud/MongoDB filter by Pointer<class>.filed ? By Pointer<class>.Pointer<class> ? By existence of data in that filed?
How can I workaround in situation when I need to check field presence if User can have may Players, User can have many Payments.
UPD
As far as I found mongo should support filtering by "dot notation"
mongodb query by sub-field
So what am I doing wrong?

Answer 1

Short answer:
No
Simplify your data structure
Long answer:
Dot notation can be used to
include documents of pointers, as you already did in your code, e.g. include(keys.user)
filter for properties of fields, e.g. {properyA: 1, propertyB: 2}. All the data is in the field, not in another document in another collection that is referenced by a Parse pointer.
Dot notation cannot be used as filter parameter for referenced pointers in a Parse query. MongoDB also does not support such a filtering, the concept of pointer is one by Parse and not by MongoDB. In a NoSQL environment like MongoDB there are no relations between tables to be used in the query language, as it is not a "relational database" like an SQL database. However Parse provides some comfort of an SQL for simple queries with its concepts of pointer, compoundQuery and matchesKeyInQuery.
If that is not sufficient in your case, simply add the fields to the collection. To the expense that you may have the same fields and data in multiple collections but with the advantage of faster query execution time.
Finding the right data structure is one of the big topics for NoSQL as there is no general right structure. The collections and document structures are basically designed as a trade off between:
execution performance
query necessity / frequency
security (access level)
and data storage size
And they are liquid and can change over time. As your app and its queries mutate you'd also change the data structure if the long term gain is greater than the one time effort.