$toLower (aggregation)
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Definition
-
$toLower
-
Converts a string to lowercase, returning the result.
$toLower
has the following syntax:The argument can be any expression as long as it resolves to a string. For more information on expressions, see Expressions.
If the argument resolves to null,
$toLower
returns an empty string""
.
Behavior
$toLower
only has a well-defined behavior for strings of ASCII characters.
Example
Consider a inventory
collection with the following documents:
The following operation uses the $toLower
operator return lowercase item
and lowercase description
value:
The operation returns the following results: