public abstract class

DB

extends Object
java.lang.Object
   ↳ com.mongodb.DB
Known Direct Subclasses

Class Overview

an abstract class that represents a logical database on a server

Summary

Fields
protected boolean _readOnly
Public Constructors
DB(Mongo mongo, String name)
Public Methods
void addOption(int option)
Adds the give option
WriteResult addUser(String username, char[] passwd, boolean readOnly)
Adds a new user for this db
WriteResult addUser(String username, char[] passwd)
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(String cmd)
Executes a database command.
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, int options)
Executes a database command.
CommandResult command(DBObject cmd)
Executes a database command.
CommandResult command(DBObject cmd, int options, DBEncoder encoder)
CommandResult command(DBObject cmd, DBEncoder encoder)
CommandResult command(DBObject 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.
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(int w, int wtimeout, boolean fsync)
CommandResult getLastError(WriteConcern concern)
@return
CommandResult getLastError()
Gets the the error (if there is one) from the previous operation on this connection.
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 
 { err : errorMessage, nPrev : countOpsBack, ok : 1 }
The value for errorMessage will be null of no error has occurred, otherwise the error message.
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()
This method is deprecated. Replaced with ReadPreference.SECONDARY
String toString()
Returns the name of this database.
Protected Methods
abstract DBCollection doGetCollection(String name)
Returns the collection represented by the string <dbName>.<collectionName>.
[Expand]
Inherited Methods
From class java.lang.Object

Fields

protected boolean _readOnly

Public Constructors

public DB (Mongo mongo, String name)

Parameters
mongo the mongo instance
name the database name

Public Methods

public void addOption (int option)

Adds the give option

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

Adds a new user for this db

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

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

Adds a new user for this db

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

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
MongoException

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

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

public abstract void cleanCursors (boolean force)

Throws
MongoException

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

public CommandResult command (String cmd)

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

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

Throws
MongoException

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

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

public CommandResult command (String cmd, int options)

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

public CommandResult command (DBObject cmd)

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
MongoException
See Also

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

Throws
MongoException

public CommandResult command (DBObject cmd, DBEncoder encoder)

Throws
MongoException

public CommandResult command (DBObject cmd, int options)

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

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

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

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

public void dropDatabase ()

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

Throws
MongoException

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

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

public void forceError ()

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

Throws
MongoException

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

public DBCollection getCollectionFromString (String s)

Returns a collection matching a given string.

Parameters
s the name of the collection
Returns
  • the collection

public Set<String> getCollectionNames ()

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

Returns
  • the names of collections in this database
Throws
MongoException

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

Returns
  • The command result
Throws
MongoException
See Also
  • {@link DB#getLastError(com.mongodb.WriteConcern) }

public CommandResult getLastError (WriteConcern concern)

@return

Parameters
concern the concern associated with "getLastError" call
Throws
MongoException
See Also
  • {@link DB#getLastError() }

public CommandResult getLastError ()

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

public Mongo getMongo ()

Gets the Mongo instance

public String getName ()

Returns the name of this database.

Returns
  • the name

public int getOptions ()

Gets the query options

public CommandResult getPreviousError ()

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

public ReadPreference getReadPreference ()

Gets the default read preference

public DB getSisterDB (String name)

Gets another database on same server

Parameters
name name of the database

public CommandResult getStats ()

Returns the result of "dbstats" command

public WriteConcern getWriteConcern ()

Gets the write concern for this database.

public boolean isAuthenticated ()

Returns true if a user has been authenticated

Returns
  • true if authenticated, false otherwise

public WriteResult removeUser (String username)

Removes a user for this db

public abstract void requestDone ()

ends the current "consistent request"

public abstract void requestEnsureConnection ()

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

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.

public void resetError ()

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

Throws
MongoException

public void resetOptions ()

Resets the query options

public void setOptions (int options)

Sets the query options

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

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

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

public void slaveOk ()

This method is deprecated.
Replaced with ReadPreference.SECONDARY

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

See Also
  • com.mongodb.ReadPreference.SECONDARY

public String toString ()

Returns the name of this database.

Returns
  • the name

Protected Methods

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