Package org.springframework.data.mongodb.core.aggregation

Class ArrayOperators.First

java.lang.Object

org.springframework.data.mongodb.core.aggregation.ArrayOperators.First

All Implemented Interfaces:

AggregationExpression, MongoExpression

Enclosing class:

ArrayOperators

public static class ArrayOperators.First
extends Object

AggregationExpression for $first that returns the first element in an array.
NOTE: Requires MongoDB 4.4 or later.

Since:

3.4

Author:

Divya Srivastava, Christoph Strobl

Method Summary

Modifier and Type	Method	Description
protected List<Object>	append(Object value)
protected List<Object>	append(Object value, org.springframework.data.mongodb.core.aggregation.AbstractAggregationExpression.Expand expandList)
protected Map<String,Object>	append(String key, Object value)
protected Map<String,Object>	appendAt(int index, String key, Object value)	Append the given key at the position in the underlying LinkedHashMap.
protected Map<String,Object>	appendTo(String key, Object value)
protected Map<String,Object>	argumentMap()	Get the argument map.
protected static List<Field>	asFields(String... fieldRefs)
protected boolean	contains(Object key)	Check if the given key is available.
static ArrayOperators.First	first(Object array)	Returns the first element in the given array.
static ArrayOperators.First	firstOf(String fieldReference)	Returns the first element in the array pointed to by the given field reference.
static ArrayOperators.First	firstOf(AggregationExpression expression)	Returns the first element of the array computed by the given expression.
protected <T> T	get(int index)	Get the value at a given index.
protected <T> T	get(Object key)	Get the value for a given key.
protected String	getMongoMethod()
protected boolean	isArgumentMap()
protected Map<String,Object>	remove(String key)
org.bson.Document	toDocument(Object value, AggregationOperationContext context)
org.bson.Document	toDocument(AggregationOperationContext context)	Turns the AggregationExpression into a Document within the given AggregationOperationContext.
protected List<Object>	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.data.mongodb.core.aggregation.AggregationExpression

toDocument

Method Details

first

public static ArrayOperators.First first(Object array)

Returns the first element in the given array.

Parameters:

array - must not be null.

Returns:

new instance of ArrayOperators.First.

firstOf

public static ArrayOperators.First firstOf(String fieldReference)

Returns the first element in the array pointed to by the given field reference.

Parameters:

fieldReference - must not be null.

Returns:

new instance of ArrayOperators.First.

firstOf

public static ArrayOperators.First firstOf(AggregationExpression expression)

Returns the first element of the array computed by the given expression.

Parameters:

expression - must not be null.

Returns:

new instance of ArrayOperators.First.

getMongoMethod

protected String getMongoMethod()

toDocument

public org.bson.Document toDocument(AggregationOperationContext context)

Description copied from interface: AggregationExpression

Turns the AggregationExpression into a Document within the given AggregationOperationContext.

Specified by:

toDocument in interface AggregationExpression

Parameters:

context - must not be null.

Returns:

the MongoDB native (Document) form of the expression.

toDocument

public org.bson.Document toDocument(Object value,
 AggregationOperationContext context)

asFields

protected static List<Field> asFields(String... fieldRefs)

append

protected List<Object> append(Object value,
 org.springframework.data.mongodb.core.aggregation.AbstractAggregationExpression.Expand expandList)

append

protected List<Object> append(Object value)

append

protected Map<String,Object> append(String key,
 Object value)

appendTo

protected Map<String,Object> appendTo(String key,
 Object value)

remove

protected Map<String,Object> remove(String key)

appendAt

protected Map<String,Object> appendAt(int index,
 String key,
 Object value)

Append the given key at the position in the underlying LinkedHashMap.

Parameters:

index -

key -

value -

Returns:

Since:

3.1

values

protected List<Object> values()

get

protected <T> T get(int index)

Get the value at a given index.

Type Parameters:

T -

Parameters:

index -

Returns:

Since:

2.1

get

protected <T> T get(Object key)

Get the value for a given key.

Type Parameters:

T -

Parameters:

key -

Returns:

Since:

2.1

isArgumentMap

protected boolean isArgumentMap()

argumentMap

protected Map<String,Object> argumentMap()

Get the argument map.

Returns:

Since:

2.1

contains

protected boolean contains(Object key)

Check if the given key is available.

Parameters:

key -

Returns:

Since:

2.1