org.mongodb.morphia.aggregation

Interface AggregationPipeline

All Known Implementing Classes:

AggregationPipelineImpl

public interface AggregationPipeline

This defines the pipeline used in aggregation operations

MongoDB documentation

Aggregation Pipeline

Method Summary

Modifier and Type	Method and Description
<U> Iterator<U>	aggregate(Class<U> target) Executes the pipeline and aggregates the output in to the type mapped by the target type using the default options as defined in AggregationOptions.
<U> Iterator<U>	aggregate(Class<U> target, AggregationOptions options) Executes the pipeline and aggregates the output in to the type mapped by the target type.
<U> Iterator<U>	aggregate(Class<U> target, AggregationOptions options, ReadPreference readPreference) Executes the pipeline and aggregates the output in to the type mapped by the target type.
<U> Iterator<U>	aggregate(String collectionName, Class<U> target, AggregationOptions options, ReadPreference readPreference) Executes the pipeline and aggregates the output in to the type mapped by the target type.
AggregationPipeline	geoNear(GeoNear geoNear) Returns an ordered stream of documents based on the proximity to a geospatial point.
AggregationPipeline	group(List<Group> id, Group... groupings)
AggregationPipeline	group(String id, Group... groupings) Groups input documents by a specified identifier expression and applies the accumulator expression(s), if specified, to each group .
AggregationPipeline	limit(int count) Passes the first n documents unmodified to the pipeline where n is the specified limit.
AggregationPipeline	lookup(String from, String localField, String foreignField, String as) Performs a left outer join to an unsharded collection in the same database to filter in documents from the “joined” collection for processing.
AggregationPipeline	match(Query query) Filters the document stream to allow only matching documents to pass unmodified into the next pipeline stage.
<U> Iterator<U>	out(Class<U> target) Places the output of the aggregation in the collection mapped by the target type using the default options as defined in AggregationOptions.
<U> Iterator<U>	out(Class<U> target, AggregationOptions options) Places the output of the aggregation in the collection mapped by the target type.
<U> Iterator<U>	out(String collectionName, Class<U> target) Places the output of the aggregation in the collection mapped by the target type using the default options as defined in AggregationOptions.
<U> Iterator<U>	out(String collectionName, Class<U> target, AggregationOptions options) Places the output of the aggregation in the collection mapped by the target type.
AggregationPipeline	project(Projection... projections) Reshapes each document in the stream, such as by adding new fields or removing existing fields.
AggregationPipeline	skip(int count) Skips the first n documents where n is the specified skip number and passes the remaining documents unmodified to the pipeline.
AggregationPipeline	sort(Sort... sorts) Reorders the document stream by a specified sort key.
AggregationPipeline	unwind(String field) Deconstructs an array field from the input documents to output a document for each element.

Method Detail

aggregate

<U> Iterator<U> aggregate(Class<U> target)

Executes the pipeline and aggregates the output in to the type mapped by the target type using the default options as defined in AggregationOptions.

Type Parameters:

U - type of the results

Parameters:

target - The class to use when iterating over the results

Returns:

an iterator of the computed results

aggregate

<U> Iterator<U> aggregate(Class<U> target,
                          AggregationOptions options)

Executes the pipeline and aggregates the output in to the type mapped by the target type.

Type Parameters:

U - type of the results

Parameters:

target - The class to use when iterating over the results

options - The options to apply to this aggregation

Returns:

an iterator of the computed results

aggregate

<U> Iterator<U> aggregate(Class<U> target,
                          AggregationOptions options,
                          ReadPreference readPreference)

Executes the pipeline and aggregates the output in to the type mapped by the target type.

Type Parameters:

U - type of the results

Parameters:

target - The class to use when iterating over the results

options - The options to apply to this aggregation

readPreference - The read preference to apply to this pipeline

Returns:

an iterator of the computed results

aggregate

<U> Iterator<U> aggregate(String collectionName,
                          Class<U> target,
                          AggregationOptions options,
                          ReadPreference readPreference)

Executes the pipeline and aggregates the output in to the type mapped by the target type.

Type Parameters:

U - type of the results

Parameters:

collectionName - The collection in which to store the results of the aggregation overriding the mapped value in target

target - The class to use when iterating over the results

options - The options to apply to this aggregation

readPreference - The read preference to apply to this pipeline

Returns:

an iterator of the computed results

geoNear

AggregationPipeline geoNear(GeoNear geoNear)

Returns an ordered stream of documents based on the proximity to a geospatial point. Incorporates the functionality of $match, $sort, and $limit for geospatial data. The output documents include an additional distance field and can include a location identifier field.

Parameters:

geoNear - the geospatial parameters to apply to the pipeline

Returns:

this

MongoDB documentation

$geoNear

group

AggregationPipeline group(String id,
                          Group... groupings)

Groups input documents by a specified identifier expression and applies the accumulator expression(s), if specified, to each group . Consumes all input documents and outputs one document per each distinct group. The output documents only contain the identifier field and, if specified, accumulated fields.

Parameters:

id - the ID of the group create

groupings - the group definitions

Returns:

this

MongoDB documentation

$group

group

AggregationPipeline group(List<Group> id,
                          Group... groupings)

Parameters:

id - the ID of the group create

groupings - the group definitions

Returns:

this

See Also:

group(String, Group...)

MongoDB documentation

$group

limit

AggregationPipeline limit(int count)

Passes the first n documents unmodified to the pipeline where n is the specified limit. For each input document, outputs either one document (for the first n documents) or zero documents (after the first n documents).

Parameters:

count - the maximum number of documents to return

Returns:

this

MongoDB documentation

$limit

lookup

AggregationPipeline lookup(String from,
                           String localField,
                           String foreignField,
                           String as)

Performs a left outer join to an unsharded collection in the same database to filter in documents from the “joined” collection for processing. The $lookup stage does an equality match between a field from the input documents with a field from the documents of the “joined” collection. To each input document, the $lookup stage adds a new array field whose elements are the matching documents from the “joined” collection. The $lookup stage passes these reshaped documents to the next stage.

Parameters:

from - the collection to join

localField - the field from the input documents

foreignField - the field from the documents of the "from" collection

as - the output array field

Returns:

this

Since:

1.2

MongoDB documentation

$lookup

match

AggregationPipeline match(Query query)

Filters the document stream to allow only matching documents to pass unmodified into the next pipeline stage. $match uses standard MongoDB queries. For each input document, outputs either one document (a match) or zero documents (no match).

Parameters:

query - the query to use when matching

Returns:

this

MongoDB documentation

$match

out

<U> Iterator<U> out(Class<U> target)

Places the output of the aggregation in the collection mapped by the target type using the default options as defined in AggregationOptions.

Type Parameters:

U - type of the results

Parameters:

target - The class to use when iterating over the results

Returns:

an iterator of the computed results

MongoDB documentation

$out

out

<U> Iterator<U> out(Class<U> target,
                    AggregationOptions options)

Places the output of the aggregation in the collection mapped by the target type.

Type Parameters:

U - type of the results

Parameters:

target - The class to use when iterating over the results

options - The options to apply to this aggregation

Returns:

an iterator of the computed results

MongoDB documentation

$out

out

<U> Iterator<U> out(String collectionName,
                    Class<U> target)

Places the output of the aggregation in the collection mapped by the target type using the default options as defined in AggregationOptions.

Type Parameters:

U - type of the results

Parameters:

collectionName - The collection in which to store the results of the aggregation overriding the mapped value in target

target - The class to use when iterating over the results

Returns:

an iterator of the computed results

MongoDB documentation

$out

out

<U> Iterator<U> out(String collectionName,
                    Class<U> target,
                    AggregationOptions options)

Places the output of the aggregation in the collection mapped by the target type.

Type Parameters:

U - type of the results

Parameters:

collectionName - The collection in which to store the results of the aggregation overriding the mapped value in target

target - The class to use when iterating over the results

options - The options to apply to this aggregation

Returns:

an iterator of the computed results

MongoDB documentation

$out

project

AggregationPipeline project(Projection... projections)

Reshapes each document in the stream, such as by adding new fields or removing existing fields. For each input document, outputs one document.

Parameters:

projections - the projections to apply to this pipeline

Returns:

this

MongoDB documentation

$project

skip

AggregationPipeline skip(int count)

Skips the first n documents where n is the specified skip number and passes the remaining documents unmodified to the pipeline. For each input document, outputs either zero documents (for the first n documents) or one document (if after the first n documents).

Parameters:

count - the number of documents to skip

Returns:

this

MongoDB documentation

$skip

sort

AggregationPipeline sort(Sort... sorts)

Reorders the document stream by a specified sort key. Only the order changes; the documents remain unmodified. For each input document, outputs one document.

Parameters:

sorts - the sorts to apply to this pipeline

Returns:

this

MongoDB documentation

$sort

unwind

AggregationPipeline unwind(String field)

Deconstructs an array field from the input documents to output a document for each element. Each output document replaces the array with an element value. For each input document, outputs n documents where n is the number of array elements and can be zero for an empty array.

Parameters:

field - the field to unwind

Returns:

this

MongoDB documentation

$unwind