In MongoDB, the $in query operator selects the documents where the value of a field equals any value in the specified array.
The $in query operator is not to be confused with the $in aggregation pipeline operator, which returns a boolean indicating whether a specified value is in the array.
In MongoDB, the $gte aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is greater than or equal to the second value.
In MongoDB, $ifNull is an aggregation pipeline operator that allows you to specify a value to use in place of null.
The way that it works is, you provide an expression and a replacement expression. If the expression evaluates to a non-null value, that expression is returned. But if the expression evaluates to a null value, $ifNull returns the value of the replacement expression.
A null value includes instances of undefined values or missing fields.
Continue readingIn MongoDB, the $gt aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is greater than the second value.
In MongoDB, the $lte aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is less than or equal to the second value.
In MongoDB, the $lt aggregation pipeline operator compares two values and returns either true or false, depending on whether or not the first value is less than the second value.
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.
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 readingIn 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.
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.