Class AccumulatorExpressions

  • java.lang.Object
    • dev.morphia.aggregation.experimental.expressions.AccumulatorExpressions

  • public final class AccumulatorExpressions
    extends Object
    Defines helper methods for accumulator expressions
    Since:
    2.0
    • Method Detail

      • sum

        public static Expression sum​(Expression first,
                                     Expression... additional)
        Calculates and returns the sum of numeric values. $sum ignores non-numeric values.
        Parameters:
        first - the first expression to sum
        additional - any subsequent expressions to include in the sum
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $sum
      • addToSet

        public static Expression addToSet​(Expression value)
        Returns an array of unique expression values for each group. Order of the array elements is undefined.
        Parameters:
        value - the value
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $addToSet
      • avg

        public static Expression avg​(Expression value,
                                     Expression... additional)
        Returns an average of numerical values. Ignores non-numeric values.
        Parameters:
        value - the value
        additional - any subsequent expressions to include in the expression
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $avg
      • first

        public static Expression first​(Expression value)
        Returns a value from the first document for each group. Order is only defined if the documents are in a defined order.
        Parameters:
        value - the value
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $first
      • last

        public static Expression last​(Expression value)
        Returns a value from the last document for each group. Order is only defined if the documents are in a defined order.
        Parameters:
        value - the value
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $last
      • push

        public static Push push()
        Returns an array of all values that result from applying an expression to each document in a group of documents that share the same group by key.

        $push is only available in the $group stage.

        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $push
      • stdDevPop

        public static Expression stdDevPop​(Expression value,
                                           Expression... additional)
        Returns the population standard deviation of the input values.
        Parameters:
        value - the value
        additional - any subsequent expressions to include in the expression
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $stdDevPop
      • stdDevSamp

        public static Expression stdDevSamp​(Expression value,
                                            Expression... additional)
        Returns the sample standard deviation of the input values.
        Parameters:
        value - the value
        additional - any subsequent expressions to include in the expression
        Returns:
        the new expression
        MongoDB documentation
        Aggregration Expression: $stdDevSamp