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MySQL NDB Cluster API Developer Guide
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2.3.26 The NdbRecAttr Class


The section describes the NdbRecAttr class and its public methods.

Parent class.  None

Child classes.  None

Description.  NdbRecAttr contains the value of an attribute. An NdbRecAttr object is used to store an attribute value after it has been retrieved using the NdbOperation::getValue() method. This object is allocated by the NDB API. A brief example is shown here:

MyRecAttr = MyOperation->getValue("ATTR2", NULL);

if(MyRecAttr == NULL)
  goto error;

if(MyTransaction->execute(Commit) == -1)
  goto error;

ndbout << MyRecAttr->u_32_value();

For additional examples, see Section 2.5.1, “NDB API Example Using Synchronous Transactions”.


An NdbRecAttr object is instantiated with its value only when NdbTransaction::execute() is invoked. Prior to this, the value is undefined. (Use NdbRecAttr::isNULL() to check whether the value is defined.) This means that an NdbRecAttr object has valid information only between the times that NdbTransaction::execute() and Ndb::closeTransaction() are called. The value of the NULL indicator is -1 until the NdbTransaction::execute() method is invoked.

Methods.  NdbRecAttr has a number of methods for retrieving values of various simple types directly from an instance of this class.


It is also possible to obtain a reference to the value regardless of its actual type, by using NdbRecAttr::aRef(); however, you should be aware that this is not type-safe, and requires a cast from the user.

The following table lists all of the public methods of this class and the purpose or use of each method:

Method Purpose / Use
~NdbRecAttr() Destructor method
aRef() Gets a pointer to the attribute value
char_value() Retrieves a Char attribute value
clone() Makes a deep copy of the RecAttr object
double_value() Retrieves a Double attribute value, as a double (8 bytes)
float_value() Retrieves a Float attribute value, as a float (4 bytes)
get_size_in_bytes() Gets the size of the attribute, in bytes
getColumn() Gets the column to which the attribute belongs
getType() Gets the attribute's type (Column::Type)
isNULL() Tests whether the attribute is NULL
int8_value() Retrieves a Tinyint attribute value, as an 8-bit integer
int32_value() Retrieves an Int attribute value, as a 32-bit integer
int64_value() Retrieves a Bigint attribute value, as a 64-bit integer
medium_value() Retrieves a Mediumint attribute value, as a 32-bit integer
short_value() Retrieves a Smallint attribute value, as a 16-bit integer
u_8_value() Retrieves a Tinyunsigned attribute value, as an unsigned 8-bit integer
u_32_value() Retrieves an Unsigned attribute value, as an unsigned 32-bit integer
u_64_value() Retrieves a Bigunsigned attribute value, as an unsigned 64-bit integer
u_char_value() Retrieves a Char attribute value, as an unsigned char
u_medium_value() Retrieves a Mediumunsigned attribute value, as an unsigned 32-bit integer
u_short_value() Retrieves a Smallunsigned attribute value, as an unsigned 16-bit integer

The NdbRecAttr class has no public constructor; an instance of this object is created using NdbTransaction::execute(). For information about the destructor, which is public, see Section, “~NdbRecAttr()”.

Types.  The NdbRecAttr class defines no public types.

Class diagram.  This diagram shows all the available methods of the NdbRecAttr class:

Figure 2.22 NdbRecAttr

Public methods of the NdbRecAttr class.

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