In MongoDB, the $filter aggregation pipeline operator returns a subset of an array based on a specified condition.
The $filter operator returns an array with only those elements that match the condition, in their original order.
Category: MongoDB
5 Ways to Check the Size of a Collection in MongoDB
In this article I present 5 ways that you can use to check the size of a MongoDB collection when using the mongo shell.
Continue readingMongoDB $exp
In MongoDB, the $exp aggregation pipeline operator raises Euler’s number (i.e. e ) to the specified exponent and returns the result.
The exponent can be any valid expression that resolves to a number.
Continue readingMongoDB $tanh
In MongoDB, the $tanh aggregation pipeline operator returns the hyperbolic tangent of a value that is measured in radians.
$tanh accepts any valid expression that resolves to a number.
The $tanh operator was introduced in MongoDB 4.2.
MongoDB $eq Aggregation Pipeline Operator
In MongoDB, the $eq aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are equivalent or not.
MongoDB $cond
In MongoDB, the $cond aggregation pipeline operator evaluates a boolean expression, and returns one of the two specified return expressions, depending on whether the boolean expression is true or false.
The $cond operator accepts two syntaxes: a longhand syntax and a shorthand syntax. Examples of each are below.
MongoDB $concatArrays
In MongoDB, the $concatArrays aggregation pipeline operator concatenates two or more arrays and returns the concatenated array.
MongoDB $concat
In MongoDB, the $concat aggregation pipeline operator concatenates two or more strings and returns the concatenated string.
MongoDB $cmp
In MongoDB, the $cmp aggregation pipeline operator compares two values and returns either -1, 1, or 0, depending on whether the first value is less than, greater than, or equal to the first value.
MongoDB $floor
In MongoDB, the $floor aggregation pipeline operator returns the largest integer less than or equal to the specified number.
$floor accepts any valid expression that resolves to a number.