-
Type: Improvement
-
Resolution: Duplicate
-
Priority: Major - P3
-
None
-
Affects Version/s: 2.5.3
-
Component/s: Aggregation Framework
-
Query
-
Query 12 (04/04/16), Query 13 (04/22/16), Query 15 (06/03/16), Query 17 (07/15/16)
-
(copied to CRM)
Syntax
{$toInt: <arbitrary expression>} {$toLong: <arbitrary expression>} {$toDouble: <arbitrary expression>} {$toDecimal: <arbitrary expression>} {$toString: <arbitrary expression>}
Examples
> db.coll.insert([ {_id: 0, x: "3.4"}, {_id: 1, x: 0.99} ]); > db.coll.aggregate([{ $project: { intField: {$toInt: "$x"} } }]) {_id: 0, intField: 3} {_id: 1, intField: 0} // Example 2 > db.coll.insert([ {_id: 0, x: {a: "b"}}, {_id: 1, x: 1.22}, {_id: 2, x: "abc"} ]); > db.coll.aggregate([{ $project: { stringField: {$toString: "$x"} } }]) {_id: 0, stringField: "{a: 'b'}"} {_id: 1, stringField: "1.22"} {_id: 2, stringField: "abc"}
Notes
- Each numeric conversion can convert from any numeric type or from a string (truncating if necessary).
- Calling $toInt on an int is a no-op, similarly for other conversions.
Errors
- If the input is of a type or value that cannot be converted:
$toInt, $toLong, $toDouble, $toDecimal accept only int, long, double, decimal, and strings that can be interpreted as the above. $toString accepts anything that can be turned into output that is parseable by the mongo shell.
Old Description
There are situations where I want to use a number as (part of) a string but $concat will only take strings and not numbers. And there are other times where I have a string of a number "2012" and I want to use it as a number and there is no operator to do this.
Seems painful to fall back to map/reduce solely because someone saves a number or date as a string
- duplicates
-
SERVER-33510 Add shorthand syntax for $convert
- Closed
- is related to
-
DRIVERS-297 Aggregation Framework Support for 3.4
- Closed
-
SERVER-23410 Improve or remove support for dates in string expressions
- Closed
-
SERVER-24947 Need a type conversion mechanism for booleans, ISODates, ObjectID
- Closed