Class ProjectionOperation

java.lang.Object

org.springframework.data.mongodb.core.aggregation.ProjectionOperation

All Implemented Interfaces:

AggregationOperation, FieldsExposingAggregationOperation

public class ProjectionOperation
extends Object
implements FieldsExposingAggregationOperation

Encapsulates the aggregation framework $project-operation.

Projection of field to be used in an Aggregation. A projection is similar to a Field inclusion/exclusion but more powerful. It can generate new fields, change values of given field etc.

We recommend to use the static factory method Aggregation.project(Fields) instead of creating instances of this class directly.

Since:

1.3

Author:

Tobias Trelle, Thomas Darimont, Oliver Gierke, Christoph Strobl, Mark Paluch, Amine Jaoui

See Also:

• MongoDB Aggregation Framework: $project

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ProjectionOperation.ArrayProjectionOperationBuilder	Builder for array projections.
static class	ProjectionOperation.ExpressionProjectionOperationBuilder	An ProjectionOperation.ProjectionOperationBuilder that is used for SpEL expression based projections.
static class	ProjectionOperation.ProjectionOperationBuilder	Builder for ProjectionOperations on a field.

Nested classes/interfaces inherited from interface FieldsExposingAggregationOperation

FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation

Constructor Summary

Constructors

Constructor	Description
ProjectionOperation()	Creates a new empty ProjectionOperation.
ProjectionOperation(Class<?> type)	Creates a new ProjectionOperation including all top level fields of the given type.
ProjectionOperation(Fields fields)	Creates a new ProjectionOperation including the given Fields.

Method Summary

Modifier and Type	Method	Description
ProjectionOperation.ProjectionOperationBuilder	and(String name)	Creates a new ProjectionOperation.ProjectionOperationBuilder to define a projection for the field with the given name.
ProjectionOperation.ProjectionOperationBuilder	and(AggregationExpression expression)
ProjectionOperation.ArrayProjectionOperationBuilder	andArrayOf(Object... values)	Includes the given values (field references, expression, plain values) as an array.
ProjectionOperation	andExclude(String... fieldNames)	Excludes the given fields from the projection.
ProjectionOperation.ExpressionProjectionOperationBuilder	andExpression(String expression, Object... params)
ProjectionOperation	andInclude(String... fieldNames)	Includes the given fields into the projection.
ProjectionOperation	andInclude(Fields fields)	Includes the given fields into the projection.
ProjectionOperation	asArray(String name)	Includes the current ProjectionOperation as an array with given name.
ExposedFields	getFields()	Returns the fields exposed by the AggregationOperation.
String	getOperator()	Return the MongoDB operator that is used for this AggregationOperation.
boolean	inheritsFields()
org.bson.Document	toDocument(AggregationOperationContext context)	Turns the AggregationOperation into a Document by using the given AggregationOperationContext.

Methods inherited from class Object

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

Methods inherited from interface AggregationOperation

toPipelineStages

Constructor Details

ProjectionOperation

public ProjectionOperation()

Creates a new empty ProjectionOperation.

ProjectionOperation

public ProjectionOperation(Fields fields)

Creates a new ProjectionOperation including the given Fields.

Parameters:

fields - must not be null.

ProjectionOperation

public ProjectionOperation(Class<?> type)

Creates a new ProjectionOperation including all top level fields of the given type.

Parameters:

type - must not be null.

Since:

2.2

Method Details

and

public ProjectionOperation.ProjectionOperationBuilder and(String name)

Creates a new ProjectionOperation.ProjectionOperationBuilder to define a projection for the field with the given name.

Parameters:

name - must not be null or empty.

Returns:

andExpression

public ProjectionOperation.ExpressionProjectionOperationBuilder andExpression(String expression,
 Object... params)

and

public ProjectionOperation.ProjectionOperationBuilder and(AggregationExpression expression)

andExclude

@Contract("_ -> new")
public ProjectionOperation andExclude(String... fieldNames)

Excludes the given fields from the projection.

Parameters:

fieldNames - must not be null.

Returns:

andInclude

@Contract("_ -> new")
public ProjectionOperation andInclude(String... fieldNames)

Includes the given fields into the projection.

Parameters:

fieldNames - must not be null.

Returns:

andInclude

@Contract("_ -> new")
public ProjectionOperation andInclude(Fields fields)

Includes the given fields into the projection.

Parameters:

fields - must not be null.

Returns:

asArray

@Contract("_ -> new")
public ProjectionOperation asArray(String name)

Includes the current ProjectionOperation as an array with given name.
If you want to specify array values directly use andArrayOf(Object...).

Parameters:

name - the target property name.

Returns:

new instance of ProjectionOperation.

Since:

2.2

andArrayOf

public ProjectionOperation.ArrayProjectionOperationBuilder andArrayOf(Object... values)

Includes the given values (field references, expression, plain values) as an array.
The target property name needs to be set via ProjectionOperation.ArrayProjectionOperationBuilder.as(String).

Parameters:

values - must not be null.

Returns:

new instance of ProjectionOperation.ArrayProjectionOperationBuilder.

Throws:

IllegalArgumentException - if the required argument it null.

Since:

2.2

getFields

public ExposedFields getFields()

Description copied from interface: FieldsExposingAggregationOperation

Returns the fields exposed by the AggregationOperation.

Specified by:

getFields in interface FieldsExposingAggregationOperation

Returns:

will never be null.

inheritsFields

public boolean inheritsFields()

Specified by:

inheritsFields in interface FieldsExposingAggregationOperation

Returns:

true to conditionally inherit fields from previous operations.

toDocument

public org.bson.Document toDocument(AggregationOperationContext context)

Description copied from interface: AggregationOperation

Turns the AggregationOperation into a Document by using the given AggregationOperationContext.

Specified by:

toDocument in interface AggregationOperation

Parameters:

context - the AggregationOperationContext to operate within. Must not be null.

Returns:

the Document

getOperator

public String getOperator()

Description copied from interface: AggregationOperation

Return the MongoDB operator that is used for this AggregationOperation. Aggregation operations should implement this method to avoid document rendering.

Specified by:

getOperator in interface AggregationOperation

Returns:

the operator used for this AggregationOperation.