Package com.mongodb

Class DBCursor

java.lang.Object

com.mongodb.DBCursor

All Implemented Interfaces:

Cursor, java.io.Closeable, java.lang.AutoCloseable, java.lang.Iterable<DBObject>, java.util.Iterator<DBObject>

@NotThreadSafe
@Deprecated(since="2021-05-27")
public class DBCursor
extends java.lang.Object
implements Cursor, java.lang.Iterable<DBObject>

Deprecated.

Usage of this API is not supported in AEM as a Cloud Service.

An iterator over database results. Doing a find() query on a collection returns a DBCursor.

An application should ensure that a cursor is closed in all circumstances, e.g. using a try-with-resources statement:

     try (DBCursor cursor = collection.find(query)) {
         while (cursor.hasNext()) {
             System.out.println(cursor.next();
         }
     }
  

Warning: Calling toArray or length on a DBCursor will irrevocably turn it into an array. This means that, if the cursor was iterating over ten million results (which it was lazily fetching from the database), suddenly there will be a ten-million element array in memory. Before converting to an array, make sure that there are a reasonable number of results using skip() and limit().

For example, to get an array of the 1000-1100th elements of a cursor, use

     List<DBObject> obj = collection.find(query).skip(1000).limit(100).toArray();
  

See Mongo.getDB(String) for further information about the effective deprecation of this class.

Constructor Summary

Constructors

Constructor	Description
DBCursor(DBCollection collection, DBObject query, DBObject fields, ReadPreference readPreference)	Deprecated. Initializes a new database cursor.
DBCursor(DBCollection collection, DBObject query, DBObject fields, ReadPreference readPreference, boolean retryReads)	Deprecated. Initializes a new database cursor.

Method Summary

Modifier and Type	Method	Description
DBCursor	addOption(int option)	Deprecated. Prefer per-option methods, e.g.
DBCursor	addSpecial(java.lang.String name, java.lang.Object value)	Deprecated. Prefer per-operator methods, e.g.
DBCursor	batchSize(int numberOfElements)	Deprecated. Limits the number of elements returned in one batch.
void	close()	Deprecated. Terminates this cursor on the server.
DBCursor	comment(java.lang.String comment)	Deprecated. Adds a comment to the query to identify queries in the database profiler output.
DBCursor	copy()	Deprecated. Creates a copy of an existing database cursor.
int	count()	Deprecated. Counts the number of objects matching the query.
DBObject	curr()	Deprecated. Returns the element the cursor is at.
DBCursor	cursorType(CursorType cursorType)	Deprecated. Sets the cursor type.
DBObject	explain()	Deprecated. Replace with direct use of the explain command using the runCommand helper method
int	getBatchSize()	Deprecated. Gets the batch size.
Collation	getCollation()	Deprecated. Returns the collation options
DBCollection	getCollection()	Deprecated. Gets the collection.
long	getCursorId()	Deprecated. Gets the server's identifier for this Cursor.
DBDecoderFactory	getDecoderFactory()	Deprecated. Gets the decoder factory that creates the decoder this cursor will use to decode objects from MongoDB.
DBObject	getKeysWanted()	Deprecated. Gets the fields to be returned.
int	getLimit()	Deprecated. Gets the query limit.
int	getOptions()	Deprecated.
DBObject	getQuery()	Deprecated. Gets the query.
ReadPreference	getReadPreference()	Deprecated. Gets the default read preference.
ServerAddress	getServerAddress()	Deprecated. Gets the address of the server that data is pulled from.
boolean	hasNext()	Deprecated. Checks if there is another object available.
DBCursor	hint(DBObject indexKeys)	Deprecated. Informs the database of indexed fields of the collection in order to improve performance.
DBCursor	hint(java.lang.String indexName)	Deprecated. Prefer hint(DBObject)
int	itcount()	Deprecated. For testing only! Iterates cursor and counts objects
java.util.Iterator<DBObject>	iterator()	Deprecated. Creates a copy of this cursor object that can be iterated.
int	length()	Deprecated. Pulls back all items into an array and returns the number of objects.
DBCursor	limit(int limit)	Deprecated. Limits the number of elements returned.
DBCursor	max(DBObject max)	Deprecated. Specifies an exclusive upper limit for the index to use in a query.
DBCursor	maxScan(int max)	Deprecated. Deprecated as of MongoDB 4.0 release
DBCursor	maxTime(long maxTime, java.util.concurrent.TimeUnit timeUnit)	Deprecated. Set the maximum execution time for operations on this cursor.
DBCursor	min(DBObject min)	Deprecated. Specifies an inclusive lower limit for the index to use in a query.
DBObject	next()	Deprecated. Returns the object the cursor is at and moves the cursor ahead by one.
DBCursor	noCursorTimeout(boolean noCursorTimeout)	Deprecated. The server normally times out idle cursors after an inactivity period (10 minutes) to prevent excess memory use.
int	numSeen()	Deprecated. Returns the number of objects through which the cursor has iterated.
DBObject	one()	Deprecated. Returns the first document that matches the query.
DBCursor	oplogReplay(boolean oplogReplay)	Deprecated. Users should not set this under normal circumstances.
DBCursor	partial(boolean partial)	Deprecated. Get partial results from a sharded cluster if one or more shards are unreachable (instead of throwing an error).
void	remove()	Deprecated.
DBCursor	resetOptions()	Deprecated.
DBCursor	returnKey()	Deprecated. Forces the cursor to only return fields included in the index.
DBCursor	setCollation(Collation collation)	Deprecated. Sets the collation options
DBCursor	setDecoderFactory(DBDecoderFactory factory)	Deprecated. Sets the factory that will be used create a DBDecoder that will be used to decode BSON documents into DBObject instances.
DBCursor	setOptions(int options)	Deprecated.
DBCursor	setReadPreference(ReadPreference readPreference)	Deprecated. Sets the read preference for this cursor.
DBCursor	showDiskLoc()	Deprecated. showDiskLoc has been deprecated in the MongoDB server.
int	size()	Deprecated. Counts the number of objects matching the query this does take limit/skip into consideration
DBCursor	skip(int numberOfElements)	Deprecated. Discards a given number of elements at the beginning of the cursor.
DBCursor	slaveOk()	Deprecated. Replaced with ReadPreference.secondaryPreferred()
DBCursor	snapshot()	Deprecated. Deprecated in MongoDB 3.6 release and removed in MongoDB 4.0 release
DBCursor	sort(DBObject orderBy)	Deprecated. Sorts this cursor's elements.
java.util.List<DBObject>	toArray()	Deprecated. Converts this cursor to an array.
java.util.List<DBObject>	toArray(int max)	Deprecated. Converts this cursor to an array.
java.lang.String	toString()	Deprecated.
DBObject	tryNext()	Deprecated. Non blocking check for tailable cursors to see if another object is available.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

DBCursor

public DBCursor(DBCollection collection,
                DBObject query,
                @Nullable
                DBObject fields,
                @Nullable
                ReadPreference readPreference)

Deprecated.

Initializes a new database cursor.

Parameters:

collection - collection to use

query - the query filter to apply

fields - keys to return from the query

readPreference - the read preference for this query

DBCursor

public DBCursor(DBCollection collection,
                DBObject query,
                @Nullable
                DBObject fields,
                @Nullable
                ReadPreference readPreference,
                boolean retryReads)

Deprecated.

Initializes a new database cursor.

Parameters:

collection - collection to use

query - the query filter to apply

fields - keys to return from the query

readPreference - the read preference for this query

retryReads - true if reads should be retried

Method Detail

copy

public DBCursor copy()

Deprecated.

Creates a copy of an existing database cursor. The new cursor is an iterator, even if the original was an array.

Returns:

the new cursor

hasNext

public boolean hasNext()

Deprecated.

Checks if there is another object available.

Note: Automatically adds the Bytes.QUERYOPTION_AWAITDATA option to any cursors with the Bytes.QUERYOPTION_TAILABLE option set. For non blocking tailable cursors see tryNext().

Specified by:

hasNext in interface java.util.Iterator<DBObject>

Returns:

true if there is another object available

next

public DBObject next()

Deprecated.

Returns the object the cursor is at and moves the cursor ahead by one.

Note: Automatically adds the Bytes.QUERYOPTION_AWAITDATA option to any cursors with the Bytes.QUERYOPTION_TAILABLE option set. For non blocking tailable cursors see tryNext().

Specified by:

next in interface java.util.Iterator<DBObject>

Returns:

the next element

tryNext

@Nullable
public DBObject tryNext()

Deprecated.

Non blocking check for tailable cursors to see if another object is available.

Returns the object the cursor is at and moves the cursor ahead by one or return null if no documents is available.

Returns:

the next element or null

Throws:

MongoException - if failed

java.lang.IllegalArgumentException - if the cursor is not tailable

curr

public DBObject curr()

Deprecated.

Returns the element the cursor is at.

Returns:

the current element

remove

public void remove()

Deprecated.

Specified by:

remove in interface java.util.Iterator<DBObject>

addOption

@Deprecated
public DBCursor addOption(int option)

Deprecated.

Prefer per-option methods, e.g. cursorType(CursorType), noCursorTimeout(boolean), etc.

Adds a query option. See Bytes.QUERYOPTION_* for list.

Parameters:

option - the option to be added

Returns:

this so calls can be chained

See Also:

Bytes

setOptions

@Deprecated
public DBCursor setOptions(int options)

Deprecated.

Sets the query option - see Bytes.QUERYOPTION_* for list.

Parameters:

options - the bitmask of options

Returns:

this so calls can be chained

See Also:

Bytes

resetOptions

@Deprecated
public DBCursor resetOptions()

Deprecated.

Resets the query options.

Returns:

this so calls can be chained

getOptions

@Deprecated
public int getOptions()

Deprecated.

Gets the query options.

Returns:

the bitmask of options

getLimit

public int getLimit()

Deprecated.

Gets the query limit.

Returns:

the limit, or 0 if no limit is set

getBatchSize

public int getBatchSize()

Deprecated.

Gets the batch size.

Returns:

the batch size

addSpecial

@Deprecated
public DBCursor addSpecial(@Nullable
                           java.lang.String name,
                           @Nullable
                           java.lang.Object value)

Deprecated.

Prefer per-operator methods, e.g. comment(String), explain(), etc.

Adds a special operator like $comment or $returnKey. For example:

    addSpecial("$returnKey", 1)
    addSpecial("$comment", "this is a special query)
 

Parameters:

name - the name of the special query operator

value - the value of the special query operator

Returns:

this so calls can be chained

comment

public DBCursor comment(java.lang.String comment)

Deprecated.

Adds a comment to the query to identify queries in the database profiler output.

Parameters:

comment - the comment that is to appear in the profiler output

Returns:

this so calls can be chained

Since:

2.12

maxScan

@Deprecated
public DBCursor maxScan(int max)

Deprecated.

Deprecated as of MongoDB 4.0 release

Limits the number of documents a cursor will return for a query.

Parameters:

max - the maximum number of documents to return

Returns:

this so calls can be chained

Since:

2.12

See Also:

limit(int)

max

public DBCursor max(DBObject max)

Deprecated.

Specifies an exclusive upper limit for the index to use in a query.

Parameters:

max - a document specifying the fields, and the upper bound values for those fields

Returns:

this so calls can be chained

Since:

2.12

min

public DBCursor min(DBObject min)

Deprecated.

Specifies an inclusive lower limit for the index to use in a query.

Parameters:

min - a document specifying the fields, and the lower bound values for those fields

Returns:

this so calls can be chained

Since:

2.12

returnKey

public DBCursor returnKey()

Deprecated.

Forces the cursor to only return fields included in the index.

Returns:

this so calls can be chained

Since:

2.12

showDiskLoc

@Deprecated
public DBCursor showDiskLoc()

Deprecated.

showDiskLoc has been deprecated in the MongoDB server. There is no replacement for it.

Modifies the documents returned to include references to the on-disk location of each document. The location will be returned in a property named $diskLoc

Returns:

this so calls can be chained

Since:

2.12

hint

public DBCursor hint(DBObject indexKeys)

Deprecated.

Informs the database of indexed fields of the collection in order to improve performance.

Parameters:

indexKeys - a DBObject with fields and direction

Returns:

same DBCursor for chaining operations

hint

@Deprecated
public DBCursor hint(java.lang.String indexName)

Deprecated.

Prefer hint(DBObject)

Informs the database of an indexed field of the collection in order to improve performance.

Parameters:

indexName - the name of an index

Returns:

same DBCursor for chaining operations

maxTime

public DBCursor maxTime(long maxTime,
                        java.util.concurrent.TimeUnit timeUnit)

Deprecated.

Set the maximum execution time for operations on this cursor.

Parameters:

maxTime - the maximum time that the server will allow the query to run, before killing the operation. A non-zero value requires a server version >= 2.6

timeUnit - the time unit

Returns:

same DBCursor for chaining operations

Since:

2.12.0

snapshot

@Deprecated
public DBCursor snapshot()

Deprecated.

Deprecated in MongoDB 3.6 release and removed in MongoDB 4.0 release

Use snapshot mode for the query. Snapshot mode prevents the cursor from returning a document more than once because an intervening write operation results in a move of the document. Even in snapshot mode, documents inserted or deleted during the lifetime of the cursor may or may not be returned. Currently, snapshot mode may not be used with sorting or explicit hints.

Returns:

this so calls can be chained

See Also:

sort(DBObject), hint(DBObject)

explain

@Deprecated
public DBObject explain()

Deprecated.

Replace with direct use of the explain command using the runCommand helper method

Returns an object containing basic information about the execution of the query that created this cursor. This creates a DBObject with a number of fields, including but not limited to:

• cursor: cursor type
• nScanned: number of records examined by the database for this query
• n: the number of records that the database returned
• millis: how long it took the database to execute the query

Returns:

a DBObject containing the explain output for this DBCursor's query

Throws:

MongoException - if the operation failed

cursorType

public DBCursor cursorType(CursorType cursorType)

Deprecated.

Sets the cursor type.

Parameters:

cursorType - the cursor type, which may not be null

Returns:

this

Since:

3.9

oplogReplay

public DBCursor oplogReplay(boolean oplogReplay)

Deprecated.

Users should not set this under normal circumstances.

Parameters:

oplogReplay - if oplog replay is enabled

Returns:

this

Since:

3.9

noCursorTimeout

public DBCursor noCursorTimeout(boolean noCursorTimeout)

Deprecated.

The server normally times out idle cursors after an inactivity period (10 minutes) to prevent excess memory use. Set this option to prevent that.

Parameters:

noCursorTimeout - true if cursor timeout is disabled

Returns:

this

Since:

3.9

partial

public DBCursor partial(boolean partial)

Deprecated.

Get partial results from a sharded cluster if one or more shards are unreachable (instead of throwing an error).

Parameters:

partial - if partial results for sharded clusters is enabled

Returns:

this

Since:

3.9

sort

public DBCursor sort(DBObject orderBy)

Deprecated.

Sorts this cursor's elements. This method must be called before getting any object from the cursor.

Parameters:

orderBy - the fields by which to sort

Returns:

a cursor pointing to the first element of the sorted results

limit

public DBCursor limit(int limit)

Deprecated.

Limits the number of elements returned. Note: parameter limit should be positive, although a negative value is supported for legacy reason. Passing a negative value will call batchSize(int) which is the preferred method.

Parameters:

limit - the number of elements to return

Returns:

a cursor to iterate the results

batchSize

public DBCursor batchSize(int numberOfElements)

Deprecated.

Limits the number of elements returned in one batch. A cursor typically fetches a batch of result objects and store them locally.

If batchSize is positive, it represents the size of each batch of objects retrieved. It can be adjusted to optimize performance and limit data transfer.

If batchSize is negative, it will limit of number objects returned, that fit within the max batch size limit (usually 4MB), and cursor will be closed. For example if batchSize is -10, then the server will return a maximum of 10 documents and as many as can fit in 4MB, then close the cursor. Note that this feature is different from limit() in that documents must fit within a maximum size, and it removes the need to send a request to close the cursor server-side.

Parameters:

numberOfElements - the number of elements to return in a batch

Returns:

this so calls can be chained

skip

public DBCursor skip(int numberOfElements)

Deprecated.

Discards a given number of elements at the beginning of the cursor.

Parameters:

numberOfElements - the number of elements to skip

Returns:

a cursor pointing to the new first element of the results

Throws:

java.lang.IllegalStateException - if the cursor has started to be iterated through

getCursorId

public long getCursorId()

Deprecated.

Description copied from interface: Cursor

Gets the server's identifier for this Cursor.

Specified by:

getCursorId in interface Cursor

Returns:

the cursor's ID, or 0 if there is no active cursor.

numSeen

public int numSeen()

Deprecated.

Returns the number of objects through which the cursor has iterated.

Returns:

the number of objects seen

close

public void close()

Deprecated.

Description copied from interface: Cursor

Terminates this cursor on the server.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface Cursor

slaveOk

@Deprecated
public DBCursor slaveOk()

Deprecated.

Replaced with ReadPreference.secondaryPreferred()

Declare that this query can run on a secondary server.

Returns:

a copy of the same cursor (for chaining)

See Also:

ReadPreference.secondaryPreferred()

iterator

public java.util.Iterator<DBObject> iterator()

Deprecated.

Creates a copy of this cursor object that can be iterated. Note: - you can iterate the DBCursor itself without calling this method - no actual data is getting copied.

Note that use of this method does not let you call close the underlying cursor in the case of either an exception or an early break. The preferred method of iteration is to use DBCursor as an Iterator, so that you can call close() on it in a finally block.

Specified by:

iterator in interface java.lang.Iterable<DBObject>

Returns:

an iterator

toArray

public java.util.List<DBObject> toArray()

Deprecated.

Converts this cursor to an array.

Returns:

an array of elements

Throws:

MongoException - if failed

toArray

public java.util.List<DBObject> toArray(int max)

Deprecated.

Converts this cursor to an array.

Parameters:

max - the maximum number of objects to return

Returns:

an array of objects

Throws:

MongoException - if failed

count

public int count()

Deprecated.

Counts the number of objects matching the query. This does not take limit/skip into consideration, and does initiate a call to the server.

Returns:

the number of objects

Throws:

MongoException - if the operation failed

See Also:

size()

one

@Nullable
public DBObject one()

Deprecated.

Returns the first document that matches the query.

Returns:

the first matching document

Since:

2.12

length

public int length()

Deprecated.

Pulls back all items into an array and returns the number of objects. Note: this can be resource intensive.

Returns:

the number of elements in the array

Throws:

MongoException - if failed

See Also:

count(), size()

itcount

public int itcount()

Deprecated.

For testing only! Iterates cursor and counts objects

Returns:

num objects

Throws:

MongoException - if failed

See Also:

count()

size

public int size()

Deprecated.

Counts the number of objects matching the query this does take limit/skip into consideration

Returns:

the number of objects

Throws:

MongoException - if the operation failed

See Also:

count()

getKeysWanted

@Nullable
public DBObject getKeysWanted()

Deprecated.

Gets the fields to be returned.

Returns:

the field selector that cursor used

getQuery

public DBObject getQuery()

Deprecated.

Gets the query.

Returns:

the query that cursor used

getCollection

public DBCollection getCollection()

Deprecated.

Gets the collection.

Returns:

the collection that data is pulled from

getServerAddress

@Nullable
public ServerAddress getServerAddress()

Deprecated.

Description copied from interface: Cursor

Gets the address of the server that data is pulled from. Note that this information may not be available until hasNext() or next() is called.

Specified by:

getServerAddress in interface Cursor

Returns:

the address of the server that data is pulled from

setReadPreference

public DBCursor setReadPreference(ReadPreference readPreference)

Deprecated.

Sets the read preference for this cursor. See the documentation for ReadPreference for more information.

Parameters:

readPreference - read preference to use

Returns:

this so calls can be chained

getReadPreference

public ReadPreference getReadPreference()

Deprecated.

Gets the default read preference.

Returns:

the readPreference used by this cursor

getCollation

@Nullable
public Collation getCollation()

Deprecated.

Returns the collation options

Returns:

the collation options

Since:

3.4

setCollation

public DBCursor setCollation(@Nullable
                             Collation collation)

Deprecated.

Sets the collation options

A null value represents the server default.

Parameters:

collation - the collation options to use

Returns:

this

Since:

3.4

setDecoderFactory

public DBCursor setDecoderFactory(DBDecoderFactory factory)

Deprecated.

Sets the factory that will be used create a DBDecoder that will be used to decode BSON documents into DBObject instances.

Parameters:

factory - the DBDecoderFactory

Returns:

this so calls can be chained

getDecoderFactory

public DBDecoderFactory getDecoderFactory()

Deprecated.

Gets the decoder factory that creates the decoder this cursor will use to decode objects from MongoDB.

Returns:

the decoder factory.

toString

public java.lang.String toString()

Deprecated.

Overrides:

toString in class java.lang.Object