$not¶
-
$not
¶ Syntax:
{ field: { $not: { <operator-expression> } } }
$not
performs a logicalNOT
operation on the specified<operator-expression>
and selects the documents that do not match the<operator-expression>
. This includes documents that do not contain thefield
.Consider the following query:
db.inventory.find( { price: { $not: { $gt: 1.99 } } } )
This query will select all documents in the
inventory
collection where:- the
price
field value is less than or equal to1.99
or - the
price
field does not exist
{ $not: { $gt: 1.99 } }
is different from the$lte
operator.{ $lte: 1.99 }
returns only the documents whereprice
field exists and its value is less than or equal to1.99
.Remember that the
$not
operator only affects other operators and cannot check fields and documents independently. So, use the$not
operator for logical disjunctions and the$ne
operator to test the contents of fields directly.Consider the following behaviors when using the
$not
operator:The operation of the
$not
operator is consistent with the behavior of other operators but may yield unexpected results with some data types like arrays.The
$not
operator does not support operations with the$regex
operator. Instead use//
or in your driver interfaces, use your language’s regular expression capability to create regular expression objects.Consider the following example which uses the pattern match expression
//
:db.inventory.find( { item: { $not: /^p.*/ } } )
The query will select all documents in the
inventory
collection where theitem
field value does not start with the letterp
.If you are using Python, you can write the above query with the PyMongo driver and Python’s
python:re.compile()
method to compile a regular expression, as follows:import re for noMatch in db.inventory.find( { "item": { "$not": re.compile("^p.*") } } ): print noMatch
- the