mongodb::ObjectId Class Reference

The ObjectId class represents a MongoDB ObjectId. More...

#include <QC_ObjectId.dox.h>

Public Member Methods
int	compare (ObjectId other)
	Compares this ObjectId to another.
	constructor ()
	Creates a new ObjectId with a generated value.
	constructor (string hex_string)
	Creates an ObjectId from a 24-character hex string.
	copy ()
	Creates a copy of the ObjectId.
bool	equals (ObjectId other)
	Checks if this ObjectId equals another.
date	getTimestamp ()
	Returns the timestamp portion of the ObjectId as a date/time value.
int	hashCode ()
	Returns a hash code for this ObjectId.
string	toString ()
	Returns the ObjectId as a 24-character hexadecimal string.

Detailed Description

The ObjectId class represents a MongoDB ObjectId.

MongoDB ObjectIds are 12-byte identifiers typically used as the default value for the _id field in MongoDB documents. They consist of:

• 4 bytes representing seconds since Unix epoch
• 5 bytes of random value
• 3 bytes of incrementing counter

Example:

# Create a new ObjectId
ObjectId oid();
printf("New ObjectId: %s\n", oid.toString());
 
# Create from hex string
ObjectId oid2("507f1f77bcf86cd799439011");
 
# Get timestamp
date dt = oid.getTimestamp();

Since

mongodb 1.0

Member Function Documentation

compare()

int mongodb::ObjectId::compare

(

ObjectId

other

)

Compares this ObjectId to another.

Code Flags:

CONSTANT

Parameters

other

the ObjectId to compare to

Returns

-1 if this ObjectId is less than other, 0 if equal, 1 if greater

Example:

int cmp = oid1.compare(oid2);

constructor() [1/2]

mongodb::ObjectId::constructor

(

)

Creates a new ObjectId with a generated value.

Example:

ObjectId oid();

constructor() [2/2]

mongodb::ObjectId::constructor

(

string

hex_string

)

Creates an ObjectId from a 24-character hex string.

Parameters

hex_string

the 24-character hexadecimal string representation of the ObjectId

Example:

ObjectId oid("507f1f77bcf86cd799439011");

Exceptions

MONGODB-OBJECTID-ERROR

the hex string is not a valid ObjectId

copy()

mongodb::ObjectId::copy

(

)

Creates a copy of the ObjectId.

Example:

ObjectId oid2 = oid.copy();

equals()

bool mongodb::ObjectId::equals

(

ObjectId

other

)

Checks if this ObjectId equals another.

Code Flags:

CONSTANT

Parameters

other

the ObjectId to compare to

Returns

True if the ObjectIds are equal

Example:

if (oid1.equals(oid2)) {
    print("Same ObjectId\n");
}

getTimestamp()

date mongodb::ObjectId::getTimestamp

(

)

Returns the timestamp portion of the ObjectId as a date/time value.

Returns

the timestamp when the ObjectId was created

Code Flags:

CONSTANT

Example:

date dt = oid.getTimestamp();

hashCode()

int mongodb::ObjectId::hashCode

(

)

Returns a hash code for this ObjectId.

Returns

the hash code

Code Flags:

CONSTANT

Example:

int h = oid.hashCode();

toString()

string mongodb::ObjectId::toString

(

)

Returns the ObjectId as a 24-character hexadecimal string.

Returns

the hexadecimal string representation

Code Flags:

CONSTANT

Example:

string str = oid.toString();

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The documentation for this class was generated from the following file:

• QC_ObjectId.dox.h