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Type: Improvement
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Resolution: Duplicate
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Priority: Minor - P4
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None
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Component/s: None
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None
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Builder Changes Needed
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$dateFromString now supports the %j format specifier, "Day of Year", which allows a user to parse a date from a string containing only the year and a number to indicate which day it is of that year.
Note that %j counts the days from 0-355, not 1-356.
Description of Linked Ticket
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") }
- depends on
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SERVER-50336 $dateFromString support for additional format specifiers (such as "%j" for day of year)
- Closed