arangodb AQL query to erase list and it's child depending of condition

Question

I have a collection of Accounts that has a list of Logs

I need to erase each Log of the Account's "logs" list if "loggedAt" field of Log is older than 5 days, without leaving orphan Logs or corrupt the references of the "logs" list.

How can i achieve this using AQL or arangosh command?

Something like this

FOR a IN account
 FOR l IN log

FILTER l._id IN a.logs
FILTER DATE_DIFF(l.loggedAt, DATE_NOW(), 'days', false) > 5

UPDATE a WITH { logs: REMOVE_VALUE( a.logs, l ) } IN account
REMOVE { _key: l._key } IN log

Account document example

_id:account/1085466856
_rev:_bIYHFNu---
_key:1085466856
{
  "_class": "com.app.Account",
  "logs": [
    "log/1085468455",
    "log/1085468456",
    "log/1085468457"
  ]
}

Account.class

@Data
@Document("account")
public class Account implements Serializable {

    private static final long serialVersionUID = -1615384653229054932L;

    @Id
    private String id;

    @Ref(lazy = false)
    private Collection<Log> logs;
}

Log document example

_id:log/1085468455
_rev:_bHhi2zu-_1
_key:1085468455
{
  "_class": "com.app.Log",
  "loggedAt": "2020-08-24T17:44:43.600Z"
}

Log.class

@Data
@Document("log")
public class Log implements Serializable {

    private static final long serialVersionUID = -1969696942832711654L;

    @Id
    private String id;

    private Date loggedAt;

}

Answer 1

You can make this in 2 AQL queries:

1. Remove logs first:

LET fiveDaysAgo = DATE_SUBTRACT(DATE_NOW(), 5, 'days')
FOR rec IN log
  FILTER DATE_DIFF(rec.loggedAt, fiveDaysAgo, 'days') >= 0
  REMOVE rec IN log

2. Clean accounts next:

FOR acc IN account
  LET validLogs = (
    FOR accLog IN acc.logs
      FOR rec IN log
        FILTER accLog == rec._id
        RETURN rec._id
  )
  FILTER LENGTH(acc.logs) != LENGTH(validLogs)
  UPDATE acc WITH {logs: validLogs} IN account

It is possible to put the queries above into one query if needed:

LET fiveDaysAgo = DATE_SUBTRACT(DATE_NOW(), 5, 'days')
FOR acc IN account
  LET invalidLogs = (
    FOR accLog IN acc.logs
      FOR rec IN log
        FILTER accLog == rec._id
        FILTER DATE_DIFF(rec.loggedAt, fiveDaysAgo, 'days') >= 0
        REMOVE rec IN log
        RETURN OLD._id
  )
  FILTER LENGTH(invalidLogs) > 0
  UPDATE acc WITH {logs: OUTERSECTION(acc.logs, invalidLogs)} IN account

However, if you have zombie records in the log collection (records without any association with an account record) the query above leaves them untouched.