com.mongodb
Class DB

java.lang.Object
  com.mongodb.DB

Direct Known Subclasses:

DBApiLayer

public abstract class DB
extends Object

an abstract class that represents a logical database on a server

MongoDB Doc Links

• databases

Field Summary

protected boolean

_readOnly

Constructor Summary

DB(Mongo mongo, String name)

Method Summary

void	addOption(int option) Adds the give option
WriteResult	addUser(String username, char[] passwd) Adds a new user for this db
WriteResult	addUser(String username, char[] passwd, boolean readOnly) Adds a new user for this db
boolean	authenticate(String username, char[] passwd) Authenticates to db with the given name and password
CommandResult	authenticateCommand(String username, char[] passwd) Authenticates to db with the given name and password
abstract void	cleanCursors(boolean force)
boolean	collectionExists(String collectionName) Checks to see if a collection by name %lt;name> exists.
CommandResult	command(DBObject cmd) Executes a database command.
CommandResult	command(DBObject cmd, DBEncoder encoder)
CommandResult	command(DBObject cmd, int options) Executes a database command.
CommandResult	command(DBObject cmd, int options, DBEncoder encoder)
CommandResult	command(DBObject cmd, int options, ReadPreference readPrefs)
CommandResult	command(DBObject cmd, int options, ReadPreference readPrefs, DBEncoder encoder) Executes a database command.
CommandResult	command(String cmd) Executes a database command.
CommandResult	command(String cmd, int options) Executes a database command.
DBCollection	createCollection(String name, DBObject options) Creates a collection with a given name and options.
CommandResult	doEval(String code, Object... args) evaluates a function on the database.
protected abstract DBCollection	doGetCollection(String name) Returns the collection represented by the string <dbName>.<collectionName>.
void	dropDatabase() Drops this database.
Object	eval(String code, Object... args) calls doEval(java.lang.String, java.lang.Object[]).
void	forceError() For testing purposes only - this method forces an error to help test error handling
DBCollection	getCollection(String name) Gets a collection with a given name.
DBCollection	getCollectionFromString(String s) Returns a collection matching a given string.
Set<String>	getCollectionNames() Returns a set containing the names of all collections in this database.
CommandResult	getLastError() Gets the the error (if there is one) from the previous operation on this connection.
CommandResult	getLastError(int w, int wtimeout, boolean fsync)
CommandResult	getLastError(WriteConcern concern)
Mongo	getMongo() Gets the Mongo instance
String	getName() Returns the name of this database.
int	getOptions() Gets the query options
CommandResult	getPreviousError() Returns the last error that occurred since start of database or a call to resetError() The return object will look like
ReadPreference	getReadPreference() Gets the default read preference
DB	getSisterDB(String name) Gets another database on same server
CommandResult	getStats() Returns the result of "dbstats" command
WriteConcern	getWriteConcern() Gets the write concern for this database.
boolean	isAuthenticated() Returns true if a user has been authenticated
WriteResult	removeUser(String username) Removes a user for this db
abstract void	requestDone() ends the current "consistent request"
abstract void	requestEnsureConnection() ensure that a connection is assigned to the current "consistent request" (from primary pool, if connected to a replica set)
abstract void	requestStart() starts a new "consistent request".
void	resetError() Resets the error memory for this database.
void	resetOptions() Resets the query options
void	setOptions(int options) Sets the query options
void	setReadOnly(Boolean b) Makes this database read-only.
void	setReadPreference(ReadPreference preference) Sets the read preference for this database.
void	setWriteConcern(WriteConcern concern) Sets the write concern for this database.
void	slaveOk() Deprecated. Replaced with ReadPreference.SECONDARY
String	toString() Returns the name of this database.

Methods inherited from class java.lang.Object

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

Field Detail

_readOnly

protected boolean _readOnly

Constructor Detail

DB

public DB(Mongo mongo,
          String name)

Parameters:

mongo - the mongo instance

name - the database name

Method Detail

requestStart

public abstract void requestStart()

starts a new "consistent request". Following this call and until requestDone() is called, all db operations should use the same underlying connection. This is useful to ensure that operations happen in a certain order with predictable results.

requestDone

public abstract void requestDone()

ends the current "consistent request"

requestEnsureConnection

public abstract void requestEnsureConnection()

ensure that a connection is assigned to the current "consistent request" (from primary pool, if connected to a replica set)

doGetCollection

protected abstract DBCollection doGetCollection(String name)

Returns the collection represented by the string <dbName>.<collectionName>.

Parameters:

name - the name of the collection

Returns:

the collection

getCollection

public DBCollection getCollection(String name)

Gets a collection with a given name. If the collection does not exist, a new collection is created.

Parameters:

name - the name of the collection to return

Returns:

the collection

createCollection

public DBCollection createCollection(String name,
                                     DBObject options)

Creates a collection with a given name and options. If the collection does not exist, a new collection is created. Note that if the options parameter is null, the creation will be deferred to when the collection is written to. Possible options:

capped

boolean: if the collection is capped

size

int: collection size (in bytes)

max

int: max number of documents

Parameters:

name - the name of the collection to return

options - options

Returns:

the collection

getCollectionFromString

public DBCollection getCollectionFromString(String s)

Returns a collection matching a given string.

Parameters:

s - the name of the collection

Returns:

the collection

command

public CommandResult command(DBObject cmd)
                      throws MongoException

Executes a database command. This method calls command(com.mongodb.DBObject, int) with 0 as query option.

Parameters:

cmd - dbobject representing the command to execute

Returns:

result of command from the database

Throws:

MongoException

See Also:

List of Commands

MongoDB Doc Links

• commands

command

public CommandResult command(DBObject cmd,
                             DBEncoder encoder)
                      throws MongoException

Throws:

MongoException

command

public CommandResult command(DBObject cmd,
                             int options,
                             DBEncoder encoder)
                      throws MongoException

Throws:

MongoException

command

public CommandResult command(DBObject cmd,
                             int options,
                             ReadPreference readPrefs)
                      throws MongoException

Throws:

MongoException

command

public CommandResult command(DBObject cmd,
                             int options,
                             ReadPreference readPrefs,
                             DBEncoder encoder)
                      throws MongoException

Executes a database command.

Parameters:

cmd - dbobject representing the command to execute

options - query options to use

readPrefs - ReadPreferences for this command (nodes selection is the biggest part of this)

Returns:

result of command from the database

Throws:

MongoException

See Also:

List of Commands

MongoDB Doc Links

• commands

command

public CommandResult command(DBObject cmd,
                             int options)
                      throws MongoException

Executes a database command.

Parameters:

cmd - dbobject representing the command to execute

options - query options to use

Returns:

result of command from the database

Throws:

MongoException

See Also:

List of Commands

MongoDB Doc Links

• commands

command

public CommandResult command(String cmd)
                      throws MongoException

Executes a database command. This method constructs a simple dbobject and calls command(com.mongodb.DBObject)

Parameters:

cmd - command to execute

Returns:

result of command from the database

Throws:

MongoException

See Also:

List of Commands

command

public CommandResult command(String cmd,
                             int options)
                      throws MongoException

Executes a database command. This method constructs a simple dbobject and calls command(com.mongodb.DBObject, int)

Parameters:

cmd - command to execute

options - query options to use

Returns:

result of command from the database

Throws:

MongoException

See Also:

List of Commands

doEval

public CommandResult doEval(String code,
                            Object... args)
                     throws MongoException

evaluates a function on the database. This is useful if you need to touch a lot of data lightly, in which case network transfer could be a bottleneck.

Parameters:

code - the function in javascript code

args - arguments to be passed to the function

Returns:

The command result

Throws:

MongoException

eval

public Object eval(String code,
                   Object... args)
            throws MongoException

calls doEval(java.lang.String, java.lang.Object[]). If the command is successful, the "retval" field is extracted and returned. Otherwise an exception is thrown.

Parameters:

code - the function in javascript code

args - arguments to be passed to the function

Returns:

The object

Throws:

MongoException

getStats

public CommandResult getStats()

Returns the result of "dbstats" command

Returns:

getName

public String getName()

Returns the name of this database.

Returns:

the name

setReadOnly

public void setReadOnly(Boolean b)

Makes this database read-only. Important note: this is a convenience setting that is only known on the client side and not persisted.

Parameters:

b - if the database should be read-only

getCollectionNames

public Set<String> getCollectionNames()
                               throws MongoException

Returns a set containing the names of all collections in this database.

Returns:

the names of collections in this database

Throws:

MongoException

collectionExists

public boolean collectionExists(String collectionName)

Checks to see if a collection by name %lt;name> exists.

Parameters:

collectionName - The collection to test for existence

Returns:

false if no collection by that name exists, true if a match to an existing collection was found

toString

public String toString()

Returns the name of this database.

Overrides:

toString in class Object

Returns:

the name

getLastError

public CommandResult getLastError()
                           throws MongoException

Gets the the error (if there is one) from the previous operation on this connection. The result of this command will look like

 { "err" :  errorMessage  , "ok" : 1.0 }
 

The value for errorMessage will be null if no error occurred, or a description otherwise. Important note: when calling this method directly, it is undefined which connection "getLastError" is called on. You may need to explicitly use a "consistent Request", see requestStart() For most purposes it is better not to call this method directly but instead use WriteConcern

Returns:

DBObject with error and status information

Throws:

MongoException

getLastError

public CommandResult getLastError(WriteConcern concern)
                           throws MongoException

Parameters:

concern - the concern associated with "getLastError" call

Returns:

Throws:

MongoException

See Also:

DB#getLastError() }

getLastError

public CommandResult getLastError(int w,
                                  int wtimeout,
                                  boolean fsync)
                           throws MongoException

Parameters:

w -

wtimeout -

fsync -

Returns:

The command result

Throws:

MongoException

See Also:

DB#getLastError(com.mongodb.WriteConcern) }

setWriteConcern

public void setWriteConcern(WriteConcern concern)

Sets the write concern for this database. It Will be used for writes to any collection in this database. See the documentation for WriteConcern for more information.

Parameters:

concern - write concern to use

getWriteConcern

public WriteConcern getWriteConcern()

Gets the write concern for this database.

Returns:

setReadPreference

public void setReadPreference(ReadPreference preference)

Sets the read preference for this database. Will be used as default for reads from any collection in this database. See the documentation for ReadPreference for more information.

Parameters:

preference - Read Preference to use

getReadPreference

public ReadPreference getReadPreference()

Gets the default read preference

Returns:

dropDatabase

public void dropDatabase()
                  throws MongoException

Drops this database. Removes all data on disk. Use with caution.

Throws:

MongoException

isAuthenticated

public boolean isAuthenticated()

Returns true if a user has been authenticated

Returns:

true if authenticated, false otherwise

MongoDB Doc Links

• authenticate

authenticate

public boolean authenticate(String username,
                            char[] passwd)
                     throws MongoException

Authenticates to db with the given name and password

Parameters:

username - name of user for this database

passwd - password of user for this database

Returns:

true if authenticated, false otherwise

Throws:

MongoException

MongoDB Doc Links

• authenticate

authenticateCommand

public CommandResult authenticateCommand(String username,
                                         char[] passwd)
                                  throws MongoException

Authenticates to db with the given name and password

Parameters:

username - name of user for this database

passwd - password of user for this database

Returns:

the CommandResult from authenticate command

Throws:

MongoException - if authentication failed due to invalid user/pass, or other exceptions like I/O

MongoDB Doc Links

• authenticate

addUser

public WriteResult addUser(String username,
                           char[] passwd)

Adds a new user for this db

Parameters:

username -

passwd -

addUser

public WriteResult addUser(String username,
                           char[] passwd,
                           boolean readOnly)

Adds a new user for this db

Parameters:

username -

passwd -

readOnly - if true, user will only be able to read

removeUser

public WriteResult removeUser(String username)

Removes a user for this db

Parameters:

username -

getPreviousError

public CommandResult getPreviousError()
                               throws MongoException

Returns the last error that occurred since start of database or a call to resetError() The return object will look like

 { err : errorMessage, nPrev : countOpsBack, ok : 1 }
  

The value for errorMessage will be null of no error has occurred, otherwise the error message. The value of countOpsBack will be the number of operations since the error occurred. Care must be taken to ensure that calls to getPreviousError go to the same connection as that of the previous operation. See requestStart() for more information.

Returns:

DBObject with error and status information

Throws:

MongoException

resetError

public void resetError()
                throws MongoException

Resets the error memory for this database. Used to clear all errors such that getPreviousError() will return no error.

Throws:

MongoException

forceError

public void forceError()
                throws MongoException

For testing purposes only - this method forces an error to help test error handling

Throws:

MongoException

getMongo

public Mongo getMongo()

Gets the Mongo instance

Returns:

getSisterDB

public DB getSisterDB(String name)

Gets another database on same server

Parameters:

name - name of the database

Returns:

slaveOk

@Deprecated
public void slaveOk()

Deprecated. Replaced with ReadPreference.SECONDARY

Makes it possible to execute "read" queries on a slave node

See Also:

com.mongodb.ReadPreference.SECONDARY

addOption

public void addOption(int option)

Adds the give option

Parameters:

option -

setOptions

public void setOptions(int options)

Sets the query options

Parameters:

options -

resetOptions

public void resetOptions()

Resets the query options

getOptions

public int getOptions()

Gets the query options

Returns:

cleanCursors

public abstract void cleanCursors(boolean force)
                           throws MongoException

Throws:

MongoException