java.lang.Object
- dev.morphia.aggregation.expressions.AccumulatorExpressions

public final class AccumulatorExpressions
extends Object

Defines helper methods for accumulator expressions

Since:: 2.0

Method Summary

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - accumulator
```
public static dev.morphia.aggregation.expressions.impls.AccumulatorExpression accumulator(String initFunction,
                                                                                          String accumulateFunction,
                                                                                          List<dev.morphia.aggregation.expressions.impls.Expression> accumulateArgs,
                                                                                          String mergeFunction)
```
    Returns an array of unique expression values for each group. Order of the array elements is undefined.
    
    Parameters:
    
    initFunction - used to initialize the state. The init function receives its arguments from the initArgs expression.
    
    accumulateFunction - used to accumulate documents. The accumulate function receives its arguments from the current state and accumulateArgs array expression.
    
    accumulateArgs - Arguments passed to the accumulate function.
    
    mergeFunction - used to merge two internal states.
    
    Returns:
    
    the new expression
    
    Since:
    
    2.1
    
    MongoDB documentation
    Aggregration Expression: $accumulator
  - addToSet
```
public static dev.morphia.aggregation.expressions.impls.Expression addToSet(dev.morphia.aggregation.expressions.impls.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 dev.morphia.aggregation.expressions.impls.Expression avg(dev.morphia.aggregation.expressions.impls.Expression value,
                                                                       dev.morphia.aggregation.expressions.impls.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
  - bottom
```
public static dev.morphia.aggregation.expressions.impls.Expression bottom(dev.morphia.aggregation.expressions.impls.Expression output,
                                                                          Sort... sortBy)
```
    Returns the bottom element within a group according to the specified sort order.
    
    Parameters:
    
    output - the expression listing the fields to use
    
    sortBy - the sort order
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $bottom
    Since server release
    5.2
  - bottomN
```
public static dev.morphia.aggregation.expressions.impls.Expression bottomN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                           dev.morphia.aggregation.expressions.impls.Expression output,
                                                                           Sort... sortBy)
```
    Returns an aggregation of the bottom n elements within a group, according to the specified sort order. If the group contains fewer than n elements, $bottomN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and has to be a positive integral expression that is either a constant or depends on the _id value for $group
    
    output - the expression listing the fields to use
    
    sortBy - the sort order
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $bottomN
    Since server release
    5.2
  - first
```
public static dev.morphia.aggregation.expressions.impls.Expression first(dev.morphia.aggregation.expressions.impls.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
  - firstN
```
public static dev.morphia.aggregation.expressions.impls.Expression firstN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                          dev.morphia.aggregation.expressions.impls.Expression input)
```
    Returns an aggregation of the first n elements within a group. The elements returned are meaningful only if in a specified sort order. If the group contains fewer than n elements, $firstN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and has to be a positive integral expression that is either a constant or depends on the _id value for $group
    
    input - the expression listing the fields to use
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $firstN
    Since server release
    5.2
  - function
```
public static dev.morphia.aggregation.expressions.impls.Expression function(String body,
                                                                            dev.morphia.aggregation.expressions.impls.Expression... args)
```
    Defines a custom aggregation function or expression in JavaScript.
    
    Parameters:
    
    body - the function body
    
    args - the function arguments
    
    Returns:
    
    the new expression
    
    Since:
    
    2.1
    
    MongoDB documentation
    Aggregration Expression: $function
  - last
```
public static dev.morphia.aggregation.expressions.impls.Expression last(dev.morphia.aggregation.expressions.impls.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
  - lastN
```
public static dev.morphia.aggregation.expressions.impls.Expression lastN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                         dev.morphia.aggregation.expressions.impls.Expression input)
```
    Returns an aggregation of the last n elements within a group. The elements returned are meaningful only if in a specified sort order. If the group contains fewer than n elements, $lastN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and has to be a positive integral expression that is either a constant or depends on the _id value for $group
    
    input - the expression listing the fields to use
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $lastN
    Since server release
    5.2
  - max
```
public static dev.morphia.aggregation.expressions.impls.Expression max(dev.morphia.aggregation.expressions.impls.Expression value)
```
    Returns the highest expression value for each group.
    
    Parameters:
    
    value - the value
    
    Returns:
    
    the new expression
    
    MongoDB documentation
    Aggregration Expression: $max
  - maxN
```
public static dev.morphia.aggregation.expressions.impls.Expression maxN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                        dev.morphia.aggregation.expressions.impls.Expression input)
```
    Returns an aggregation of the max n elements within a group. The elements returned are meaningful only if in a specified sort order. If the group contains fewer than n elements, $maxN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and n has to be a positive integral expression that is either a constant or depends on the _id value for $group.
    
    input - the expression that is the input to $maxN. It is evaluated for each element in the group and $maxN preserves the maximum n values.
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $maxN
    Since server release
    5.2
  - min
```
public static dev.morphia.aggregation.expressions.impls.Expression min(dev.morphia.aggregation.expressions.impls.Expression value)
```
    Returns the lowest expression value for each group.
    
    Parameters:
    
    value - the value
    
    Returns:
    
    the new expression
    
    MongoDB documentation
    Aggregration Expression: $min
  - minN
```
public static dev.morphia.aggregation.expressions.impls.Expression minN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                        dev.morphia.aggregation.expressions.impls.Expression input)
```
    Returns an aggregation of the min n elements within a group. The elements returned are meaningful only if in a specified sort order. If the group contains fewer than n elements, $minN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and n has to be a positive integral expression that is either a constant or depends on the _id value for $group.
    
    input - the expression that is the input to $minN. It is evaluated for each element in the group and $minN preserves the minimum n values.
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $minN
    Since server release
    5.2
  - push
```
public static dev.morphia.aggregation.expressions.impls.Expression push(dev.morphia.aggregation.expressions.impls.Expression value)
```
    Returns an array of expression values for each group.
    
    Parameters:
    
    value - the value
    
    Returns:
    
    the new expression
    
    MongoDB documentation
    Aggregration Expression: $push
  - push
```
public static dev.morphia.aggregation.expressions.impls.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
  - sum
```
public static dev.morphia.aggregation.expressions.impls.Expression sum(dev.morphia.aggregation.expressions.impls.Expression first,
                                                                       dev.morphia.aggregation.expressions.impls.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
  - top
```
public static dev.morphia.aggregation.expressions.impls.Expression top(dev.morphia.aggregation.expressions.impls.Expression output,
                                                                       Sort... sortBy)
```
    Returns the top element within a group according to the specified sort order.
    
    Parameters:
    
    output - the expression listing the fields to use
    
    sortBy - the sort order
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $top
    Since server release
    5.2
  - topN
```
public static dev.morphia.aggregation.expressions.impls.Expression topN(dev.morphia.aggregation.expressions.impls.Expression n,
                                                                        dev.morphia.aggregation.expressions.impls.Expression output,
                                                                        Sort... sortBy)
```
    Returns an aggregation of the top n elements within a group, according to the specified sort order. If the group contains fewer than n elements, $topN returns all elements in the group.
    
    Parameters:
    
    n - the number of results per group and has to be a positive integral expression that is either a constant or depends on the _id value for $group
    
    output - the expression listing the fields to use
    
    sortBy - the sort order
    
    Returns:
    
    the expression
    
    Since:
    
    2.3
    
    MongoDB documentation
    Aggregration Expression: $topN
    Since server release
    5.2
  - stdDevPop
```
@Deprecated
public static dev.morphia.aggregation.expressions.impls.Expression stdDevPop(dev.morphia.aggregation.expressions.impls.Expression value,
                                                                             dev.morphia.aggregation.expressions.impls.Expression... additional)
```
    Deprecated.
    use WindowExpressions.stdDevPop(Expression, Expression...)
    
    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
```
@Deprecated
public static dev.morphia.aggregation.expressions.impls.Expression stdDevSamp(dev.morphia.aggregation.expressions.impls.Expression value,
                                                                              dev.morphia.aggregation.expressions.impls.Expression... additional)
```
    Deprecated.
    use WindowExpressions.stdDevSamp(Expression, Expression...)
    
    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

Modifier and Type	Method	Description
`static dev.morphia.aggregation.expressions.impls.AccumulatorExpression`	`accumulator(String initFunction, String accumulateFunction, List<dev.morphia.aggregation.expressions.impls.Expression> accumulateArgs, String mergeFunction)`	Returns an array of unique expression values for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`addToSet(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns an array of unique expression values for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`avg(dev.morphia.aggregation.expressions.impls.Expression value, dev.morphia.aggregation.expressions.impls.Expression... additional)`	Returns an average of numerical values.
`static dev.morphia.aggregation.expressions.impls.Expression`	`bottom(dev.morphia.aggregation.expressions.impls.Expression output, Sort... sortBy)`	Returns the bottom element within a group according to the specified sort order.
`static dev.morphia.aggregation.expressions.impls.Expression`	`bottomN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression output, Sort... sortBy)`	Returns an aggregation of the bottom n elements within a group, according to the specified sort order.
`static dev.morphia.aggregation.expressions.impls.Expression`	`first(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns a value from the first document for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`firstN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression input)`	Returns an aggregation of the first n elements within a group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`function(String body, dev.morphia.aggregation.expressions.impls.Expression... args)`	Defines a custom aggregation function or expression in JavaScript.
`static dev.morphia.aggregation.expressions.impls.Expression`	`last(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns a value from the last document for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`lastN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression input)`	Returns an aggregation of the last n elements within a group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`max(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns the highest expression value for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`maxN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression input)`	Returns an aggregation of the max n elements within a group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`min(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns the lowest expression value for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`minN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression input)`	Returns an aggregation of the min n elements within a group.
`static dev.morphia.aggregation.expressions.impls.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.
`static dev.morphia.aggregation.expressions.impls.Expression`	`push(dev.morphia.aggregation.expressions.impls.Expression value)`	Returns an array of expression values for each group.
`static dev.morphia.aggregation.expressions.impls.Expression`	`stdDevPop(dev.morphia.aggregation.expressions.impls.Expression value, dev.morphia.aggregation.expressions.impls.Expression... additional)`	Deprecated. use `WindowExpressions.stdDevPop(Expression, Expression...)`
`static dev.morphia.aggregation.expressions.impls.Expression`	`stdDevSamp(dev.morphia.aggregation.expressions.impls.Expression value, dev.morphia.aggregation.expressions.impls.Expression... additional)`	Deprecated. use `WindowExpressions.stdDevSamp(Expression, Expression...)`
`static dev.morphia.aggregation.expressions.impls.Expression`	`sum(dev.morphia.aggregation.expressions.impls.Expression first, dev.morphia.aggregation.expressions.impls.Expression... additional)`	Calculates and returns the sum of numeric values.
`static dev.morphia.aggregation.expressions.impls.Expression`	`top(dev.morphia.aggregation.expressions.impls.Expression output, Sort... sortBy)`	Returns the top element within a group according to the specified sort order.
`static dev.morphia.aggregation.expressions.impls.Expression`	`topN(dev.morphia.aggregation.expressions.impls.Expression n, dev.morphia.aggregation.expressions.impls.Expression output, Sort... sortBy)`	Returns an aggregation of the top n elements within a group, according to the specified sort order.

Class AccumulatorExpressions

Method Summary

Methods inherited from class java.lang.Object

Method Detail

accumulator

addToSet

avg

bottom

bottomN

first

firstN

function

last

lastN

max

maxN

min

minN

push

push

sum

top

topN

stdDevPop

stdDevSamp