com.mongodb
Class DB

java.lang.Object
  com.mongodb.DB

Direct Known Subclasses:

DBApiLayer

public abstract class DB
extends Object

a logical database on a server

MongoDB Doc Links

• databases

Nested Class Summary

static class

DB.WriteConcern Settings for strictness of error checking on writes (inserts, updates, and removes).

Field Summary

protected boolean

_readOnly

Constructor Summary

DB(String name)

Method Summary

void	addUser(String username, char[] passwd)
boolean	authenticate(String username, char[] passwd) Authenticates connection/db with given name and password
boolean	collectionExists(String collectionName) Checks to see if a collection by name %lt;name> exists.
CommandResult	command(DBObject cmd) Execute a database command directly.
CommandResult	command(String cmd)
DBCollection	createCollection(String name, DBObject o) Creates a collection with a given name and options.
CommandResult	doEval(String code, Object... args)
protected abstract DBCollection	doGetCollection(String name)
void	dropDatabase() Drops this database.
Object	eval(String code, Object... args)
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.
abstract DBCollection	getCollectionFromFull(String fullNameSpace) Returns the collection represented by the string <dbName>.<collectionName>.
DBCollection	getCollectionFromString(String s) Returns a collection matching a given string.
Set<String>	getCollectionNames() Returns a set of the names of collections in this database.
CommandResult	getLastError() Gets the the error (if there is one) from the previous operation.
String	getName() Returns the name of this database.
CommandResult	getPreviousError() Returns the last error that occurred since start of database or a call to resetError() The return object will look like
abstract DB	getSisterDB(String dbName)
DB.WriteConcern	getWriteConcern() Get the write concern for this database.
abstract void	requestDone()
abstract void	requestEnsureConnection()
abstract void	requestStart()
void	resetError() Resets the error memory for this database.
void	resetIndexCache() Clears any indices that have not yet been applied to the collections in this database.
void	setReadOnly(Boolean b) Makes this database read-only
void	setWriteConcern(DB.WriteConcern concern) Set the write concern for this database.
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(String name)

Method Detail

requestStart

public abstract void requestStart()

requestDone

public abstract void requestDone()

requestEnsureConnection

public abstract void requestEnsureConnection()

getCollectionFromFull

public abstract DBCollection getCollectionFromFull(String fullNameSpace)

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

Parameters:

fullNameSpace - the string

Returns:

the collection

doGetCollection

protected abstract DBCollection doGetCollection(String name)

getSisterDB

public abstract DB getSisterDB(String dbName)

getCollection

public final 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 final DBCollection createCollection(String name,
                                           DBObject o)

Creates a collection with a given name and options. If the collection does not exist, a new collection is created. Possible options:

capped

boolean: if the collection is capped

size

int: collection size

max

int: max number of documents

Parameters:

name - the name of the collection to return

o - 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

Execute a database command directly.

Returns:

the result of the command from the database

Throws:

MongoException

See Also:

Mongo Commands

MongoDB Doc Links

• commands

command

public CommandResult command(String cmd)
                      throws MongoException

Throws:

MongoException

doEval

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

Throws:

MongoException

eval

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

Throws:

MongoException

getName

public String getName()

Returns the name of this database.

Returns:

the name

setReadOnly

public void setReadOnly(Boolean b)

Makes this database read-only

Parameters:

b - if the database should be read-only

getCollectionNames

public Set<String> getCollectionNames()
                               throws MongoException

Returns a set of the names of 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

resetIndexCache

public void resetIndexCache()

Clears any indices that have not yet been applied to the collections in this database.

getLastError

public CommandResult getLastError()
                           throws MongoException

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

 { "err" :  errorMessage  , "ok" : 1.0 , "_ns" : "$cmd"}
 

The value for errorMessage will be null if no error occurred, or a description otherwise. Care must be taken to ensure that calls to getLastError go to the same connection as that of the previous operation. See com.mongodb.Mongo.requestStart for more information.

Returns:

DBObject with error and status information

Throws:

MongoException

setWriteConcern

public void setWriteConcern(DB.WriteConcern concern)

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

Parameters:

concern - write concern to use

getWriteConcern

public DB.WriteConcern getWriteConcern()

Get the write concern for this database.

dropDatabase

public void dropDatabase()
                  throws MongoException

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

Throws:

MongoException

authenticate

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

Authenticates connection/db with 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

addUser

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

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 errormMessage will be null of no error has ocurred, or the 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 com.mongodb.Mongo.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