[SERVER-50336] $dateFromString support for additional format specifiers (such as "%j" for day of year) Created: 17/Aug/20  Updated: 29/Oct/23  Resolved: 27/Jan/23

Status: Closed
Project: Core Server
Component/s: Aggregation Framework, Querying
Affects Version/s: None
Fix Version/s: 6.3.0-rc0

Type: Improvement Priority: Major - P3
Reporter: Alex Bevilacqua Assignee: Jennifer Peshansky (Inactive)
Resolution: Fixed Votes: 2
Labels: qexec-team
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
is depended on by DRIVERS-2536 $dateFromString support for additiona... Closed
Documented
is documented by DOCS-15857 [SERVER] Investigate changes in SERVE... Closed
Issue split
split to SERVER-73402 timelib support for additional format... Closed
Related
is related to SERVER-74002 Day-of-year (%j) parsing inconsistency Closed
Assigned Teams:
Query Execution
Backwards Compatibility: Fully Compatible
Participants:
Case:

 Description   

The $dateFromString Format Specifiers don't include the strftime %j modifier which is used to decode the day of the year as a decimal number (range 001 to 366).

It appears that this modifier is understood as part of kDateToStringFormatMap from timelib's TIMELIB_FORMAT_DAY_OF_YEAR when converting from a date to a string, but not from a string to a date.

For example:

db.foo.drop()
db.foo.insert({ _id: 1, d: "2020-194-14:24:45.463" });
db.foo.aggregate( [ {
   $project: {
      date: {
         $dateFromString: {
            dateString: "%d",
            format: "%Y-%j-%H:%M:%S.%L"
         }
      }
   }
} ] )
// "errmsg" : "Failed to optimize pipeline :: caused by :: Invalid format character '%j' in format string",

Note that for the above we were able to work around this limitation as follows:

db.foo.drop()
db.foo.insert({ _id: 1, d: "2020-194-14:24:45.463" });
db.foo.aggregate([
{ $project: {
    date: {
        $let: {
            vars: {
                parts: { $split: [ "$d", "-" ] }
            },
            in: { 
                $add: [ 
                    { $toDate: { $concat: [ 
                        { $arrayElemAt: [ "$$parts", 0 ] }, 
                        "-01-01T", 
                        { $arrayElemAt: [ "$$parts", 2 ] } ] 
                    } }, 
                    { $multiply: [ 
                        { $subtract: [ 
                            { $toInt: { $arrayElemAt: [ "$$parts", 1 ] } }, 
                            1 ] }, 86400000 ] }
                ] 
            } 
        }
    }
}}
]);
// { "_id" : 1, "date" : ISODate("2020-07-12T14:24:45.463Z") }



 Comments   
Comment by Githook User [ 27/Jan/23 ]

Author:

{'name': 'Jennifer Peshansky', 'email': 'jennifer.peshansky@mongodb.com', 'username': 'jenniferpeshansky'}

Message: SERVER-50336 Add %j format specifier to dateToString
Branch: master
https://github.com/mongodb/mongo/commit/33190227bdd2c21328afe7f41ace33bf5d64eeab

Comment by Asya Kamsky [ 22/Dec/22 ]

Seems rather peculiar there's no symmetry between conversion from and to string.

Question came up about %B and %b 

This seems like it would might an easy quick win or neweng ticket, no?

 

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