In MongoDB, the $rand aggregation pipeline operator returns a random float between 0 and 1.
The floating point value has up to 17 digits after the decimal point. Any trailing zeros are dropped, so the number of digits may vary.
The $rand operator was introduced in MongoDB 4.4.2.
In MongoDB, the $ne aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are not equivalent.
In MongoDB, the $in aggregation pipeline operator returns a boolean indicating whether a specified value is in the array.
The $in aggregation pipeline operator is not to be confused with the $in query operator, which selects the documents where the value of a field equals any value in the specified array.
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 $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, 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.
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