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$mod (aggregation)
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Definition
$modDivides one number by another and returns the remainder.
The
$modexpression has the following syntax:{ $mod: [ <expression1>, <expression2> ] } The first argument is the dividend, and the second argument is the divisor; i.e. first argument is divided by the second argument.
The arguments can be any valid expression as long as they resolve to numbers. For more information on expressions, see Expressions.
Example
Consider a planning collection with the following documents:
{ "_id" : 1, "project" : "A", "hours" : 80, "tasks" : 7 } { "_id" : 2, "project" : "B", "hours" : 40, "tasks" : 4 }
The following aggregation uses the $mod expression to
return the remainder of the hours field divided by the tasks
field:
db.planning.aggregate( [ { $project: { remainder: { $mod: [ "$hours", "$tasks" ] } } } ] )
The operation returns the following results:
{ "_id" : 1, "remainder" : 3 } { "_id" : 2, "remainder" : 0 }