Navigation

$rtrim (aggregation)

On this page

  • Definition
  • Behavior
  • Example
$rtrim

New in version 4.0.

Removes whitespace characters, including null, or the specified characters from the end of a string.

$rtrim has the following syntax:

{ $rtrim: { input: <string>, chars: <string> } }

The $rtrim takes a document with the following fields:

Field
Description
input
The string to trim. The argument can be any valid expression that resolves to a string. For more information on expressions, see Expressions.
chars

Optional. The character(s) to trim from the end of the input.

The argument can be any valid expression that resolves to a string. The $rtrim operator breaks down the string into individual UTF code point to trim from input.

If unspecified, $rtrim removes whitespace characters, including the null character. For the list of whitespace characters, see Whitespace Characters.

Tip
See also:
  • By default, $rtrim removes whitespace, including the null character, from the end of the input string:

    Example
    Results
    { $rtrim: { input: " \n good bye \t " } }
    " \n good bye"
  • You can override the default characters to trim using the chars field.

    For example, the following trims any g and e from the end of the input string. Since the input ends with a whitespace, neither character can be trimmed from the end of the string.

    Example
    Results
    { $rtrim: { input: "ggggoodbyeeeee ", chars: "ge" } }
    "ggggoodbyeeeee "
  • If overriding the default characters to trim, you can explicitly include the whitespace character(s) to trim in the chars field.

    For example, the following trims any space or e from the end of the input string.

    Example
    Results
    { $rtrim: { input: " ggggoodbyeeeee ", chars: "e " } }
    " ggggoodby"

By default, $rtrim removes the following whitespace, including the null character:

Unicode
Escape sequence
Description
U+0000
'0'
Null character
U+0020
' '
Space
U+0009
't'
Horizontal tab
U+000A
'n'
Line feed/new line
U+000B
'v'
Vertical tab
U+000C
'f'
Form feed
U+000D
'r'
Carriage return
U+00A0
Non-breaking space
U+1680
Ogham space mark
U+2000
En quad
U+2001
Em quad
U+2002
En space
U+2003
Em space
U+2004
Three-per-em space
U+2005
Four-per-em space
U+2006
Six-per-em space
U+2007
Figure space
U+2008
Punctuation space
U+2009
Thin space
U+200A
Hair space

Consider an inventory collection with the following documents:

{ "_id" : 1, "item" : "ABC1", quarter: "13Q1", "description" : " product 1" }
{ "_id" : 2, "item" : "ABC2", quarter: "13Q4", "description" : "product 2 \n The product is in stock. \n\n " }
{ "_id" : 3, "item" : "XYZ1", quarter: "14Q2", "description" : null }

The following operation uses the $rtrim operator to remove trailing whitespace from the description field:

db.inventory.aggregate([
{ $project: { item: 1, description: { $rtrim: { input: "$description" } } } }
])

The operation returns the following results:

{ "_id" : 1, "item" : "ABC1", "description" : " product 1" }
{ "_id" : 2, "item" : "ABC2", "description" : "product 2 \n The product is in stock." }
{ "_id" : 3, "item" : "XYZ1", "description" : null }
Give Feedback

On this page

  • Definition
  • Behavior
  • Example