Package dev.morphia.aggregation

Class Group

java.lang.Object

dev.morphia.aggregation.Group

public final class Group
extends java.lang.Object

Defines a group pipeline stage.

MongoDB documentation

reference/operator/aggregation/group/ $group

Method Summary

Modifier and Type	Method	Description
static Accumulator	addToSet(java.lang.String field)	Returns an array of all unique values that results from applying an expression to each document in a group of documents that share the same group by key.
static Accumulator	average(java.lang.String field)	Returns the average value of the numeric values that result from applying a specified expression to each document in a group of documents that share the same group by key.
static Accumulator	first(java.lang.String field)	Returns the value that results from applying an expression to the first document in a group of documents that share the same group by key.
Accumulator	getAccumulator()
java.lang.String	getName()
Group	getNested()
java.util.List<Projection>	getProjections()
java.lang.String	getSourceField()
static Group	grouping(java.lang.String name)	Creates a named grouping
static Group	grouping(java.lang.String name, Accumulator accumulator)	Creates a named grouping on a field
static Group	grouping(java.lang.String name, Group group)	Creates a named grouping
static Group	grouping(java.lang.String name, Projection... projections)	Creates a named grouping
static Group	grouping(java.lang.String name, java.lang.String sourceField)	Creates a named grouping on a field
static java.util.List<Group>	id(Group... fields)	Create a group of Groups for use as an ID
static Accumulator	last(java.lang.String field)	Returns the value that results from applying an expression to the last document in a group of documents that share the same group by a field.
static Accumulator	max(java.lang.String field)	Returns the highest value that results from applying an expression to each document in a group of documents that share the same group by key.
static Accumulator	min(java.lang.String field)	Returns the lowest value that results from applying an expression to each document in a group of documents that share the same group by key.
static Accumulator	push(java.lang.String field)	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 Accumulator	sum(java.lang.String field)	Calculates and returns the sum of all the numeric values that result from applying a specified expression to each document in a group of documents that share the same group by key.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

id

public static java.util.List<Group> id(Group... fields)

Create a group of Groups for use as an ID

Parameters:

fields - the Groups to group

Returns:

the Group

grouping

public static Group grouping(java.lang.String name)

Creates a named grouping

Parameters:

name - the field name

Returns:

the Group

grouping

public static Group grouping(java.lang.String name,
                             Projection... projections)

Creates a named grouping

Parameters:

name - the field name

projections - the fields to create

Returns:

the Group

grouping

public static Group grouping(java.lang.String name,
                             Group group)

Creates a named grouping

Parameters:

name - the field name

group - the fields to create

Returns:

the Group

grouping

public static Group grouping(java.lang.String name,
                             java.lang.String sourceField)

Creates a named grouping on a field

Parameters:

name - the group name

sourceField - the field name

Returns:

the Group

grouping

public static Group grouping(java.lang.String name,
                             Accumulator accumulator)

Creates a named grouping on a field

Parameters:

name - the group name

accumulator - the Accumulator to apply to the field

Returns:

the Group

addToSet

public static Accumulator addToSet(java.lang.String field)

Returns an array of all unique values that results from applying an expression to each document in a group of documents that share the same group by key. Order of the elements in the output array is unspecified.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/addToSet $addToSet

average

public static Accumulator average(java.lang.String field)

Returns the average value of the numeric values that result from applying a specified expression to each document in a group of documents that share the same group by key. $avg ignores non-numeric values.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/avg $avg

first

public static Accumulator first(java.lang.String field)

Returns the value that results from applying an expression to the first document in a group of documents that share the same group by key. Only meaningful when documents are in a defined order.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/first $first

last

public static Accumulator last(java.lang.String field)

Returns the value that results from applying an expression to the last document in a group of documents that share the same group by a field. Only meaningful when documents are in a defined order.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/last $last

max

public static Accumulator max(java.lang.String field)

Returns the highest value that results from applying an expression to each document in a group of documents that share the same group by key.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/max $max

min

public static Accumulator min(java.lang.String field)

Returns the lowest value that results from applying an expression to each document in a group of documents that share the same group by key.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/min $min

push

public static Accumulator push(java.lang.String field)

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.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/push $push

sum

public static Accumulator sum(java.lang.String field)

Calculates and returns the sum of all the numeric values that result from applying a specified expression to each document in a group of documents that share the same group by key. $sum ignores non-numeric values.

Parameters:

field - the field to process

Returns:

an Accumulator

MongoDB documentation

reference/operator/aggregation/sum $sum

getAccumulator

public Accumulator getAccumulator()

Returns:

the accumulator for this Group

getName

public java.lang.String getName()

Returns:

the name of the group

getSourceField

public java.lang.String getSourceField()

Returns:

the source field for the group

getProjections

public java.util.List<Projection> getProjections()

Returns:

the projections for the group

getNested

public Group getNested()

Returns:

the nested group