Dv::Sql::Object Class Reference

A class that represents a row in a database table or in a query result. More...

#include <object.h>

Inheritance diagram for Dv::Sql::Object:

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Collaboration diagram for Dv::Sql::Object:

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List of all members.

Classes
class	ColumnRef
	A class that represents a reference to a column value in an Object. More...
Public Types
typedef Dv::Sql::Set < Dv::Sql::Object >	Set
	Type representing a set of rows.
typedef Dv::shared_ptr< Object >	Ref
	Type of (reference counted) pointer to Object.
Public Member Functions
	Object (Dv::Sql::Db &db, size_t arity)
	Create an empty object with a given arity.
	Object (Table::Ref table) throw (std::logic_error)
	Create an empty object associated with a given table.
	Object (Table::Ref table, SelectExp select_exp, const std::string &rest="") throw (std::logic_error, std::runtime_error)
	Create an object containing the first row of a "select *" statement from a database table.
	Object (Dv::Sql::Command &q, unsigned int r=0, const Table::Ref &table=Table::Ref(0)) throw (std::logic_error, std::runtime_error)
	Create an object containing the r'th row of the answer of a query.
	Object (Dv::Sql::Db &db, const std::string &prefix, SelectExp select_exp, const std::string &rest="") throw (std::logic_error, std::runtime_error)
	Create an object containing the first row of the answer of a query.
	Object (Dv::Sql::Db &db, const std::string &query) throw (std::logic_error, std::runtime_error)
	Create an object containing the first row of the answer of a query for which the complete text is provided.
	Object (const Dv::Sql::Object &source, const Dv::Sql::Reference &ref) throw (std::runtime_error, std::logic_error)
	Create an object from the result of following a reference.
virtual	~Object ()
	Destructor.
bool	set (Dv::Sql::Command &q, unsigned int r=0) throw (std::logic_error)
	Set the column values of this object to those of the r'th row of the result of a query.
size_t	arity () const
	Number of column values in this object.
ColumnRef	operator[] (size_t i) throw (std::logic_error)
	Return a reference to the i'th column in this object.
ColumnRef	operator[] (const std::string &col_name) throw (std::logic_error)
	Return a reference to a named column in this object.
ColumnRef	operator[] (const Table::Column &column) throw (std::logic_error)
	Return a reference to a column in this object.
virtual std::ostream &	print (std::ostream &os) const
	Print a readable representation of this object to a stream.
Dv::Sql::Db &	db () const
	The database connection of this object.
Object &	operator= (const Object &o) throw (std::logic_error)
	Assignment operator.
const Dv::Sql::Table::Ref	table () const throw (std::logic_error)
	Return a reference to the associated Dv::Sql::Table of this object.
bool	has_db_table () const
	Is this object associated with a database table?
Dv::Sql::Table::Ref	db_table () const throw (std::logic_error)
	Return a reference to the associated database Dv::Sql::Table of this object.
const Dv::Sql::Table::Column *	column (size_t i) const throw (std::logic_error)
	Retrieve column information for this object.
size_t	match_first () throw (std::logic_error)
	Retrieve the first row, if any, that matches the dirty column values in this object.
bool	refresh () throw (std::logic_error)
	Retrieve the unique row, if any, that matches the primary key column values of this object.
void	insert () throw (std::runtime_error)
	Insert the present object into a database, using an Sql 'insert' statement.
void	update () throw (std::runtime_error)
	Save dirty column values of an object to the database.
void	replace () throw (std::runtime_error)
	Save current state of the object to the database.
void	erase () throw (std::runtime_error)
	Remove the object from the database.
void	erase (const Dv::Sql::SelectExp &exp) const
	Remove all objects from the table that satisfy some select expression.
Dv::Sql::Command::Ref	match_query (const std::string &rest="") const throw (std::logic_error)
	Create (and execute) a 'select' query out of the dirty columns of this object.
Dv::Sql::SelectExp	match_exp () const throw (std::logic_error)
	Return a boolean expression that expresses a match with the dirty columns of this object.
Dv::Sql::Command::Ref	select (const Dv::Sql::SelectExp &where_exp, const std::string &rest="") const throw (std::logic_error)
	Create (and execute) a query.
template<typename T >
Object &	set (size_t i, const T &t) throw (std::logic_error)
	Set a column value for this object.
template<typename T >
Object &	set (const Table::Column &c, const T &t) throw (std::logic_error)
	Set a column value for this object.
template<typename T >
Object &	set (const std::string &col_name, const T &t) throw (std::logic_error)
	Set a column value for this object.
template<typename T >
T	get (size_t i) const throw (std::logic_error)
	Retrieve a column value for this object.
template<typename T >
T	get (const Table::Column &c) const throw (std::logic_error)
	Retrieve a column value for this object.
template<typename T >
T	get (const std::string &col_name) const throw (std::logic_error)
	Retrieve a column value for this object.
Set::Ref	references (const Reference &ref) const throw (std::logic_error)
	Return a reference to the set of objects obtained by following a given reference in reverse.
Object &	copy_data (size_t to_i, const Object &from, size_t from_i, bool dirty) throw (std::logic_error)
	Copy a column value from another object to this one.
const std::string &	get_data (const Table::Column &c) const
	Obtain the data value associated with this object.
Protected Member Functions
Object &	set_data (size_t i, const std::string &value, bool dirty) throw (std::logic_error)
	Set the value of column `i` in this object to `value`.
const std::string &	data (size_t i) const
	Obtain the data value associated with this object.
void	set_null (size_t i, bool new_value) throw ()
	Set the null status of a column.
bool	null (size_t i) const throw ()
	Is a column value null?
void	set_dirty (size_t i, bool new_value) throw ()
	Set the dirty status of a column.
bool	dirty (size_t i) const throw ()
	Is a column value dirty?
Private Member Functions
void	set_table (Dv::Sql::Table::Ref table) throw (std::logic_error)
	Change the associated table of this object.
Private Attributes
Dv::Sql::Db &	db_
	Database connection associated with this object.
std::vector< bool >	dirty_
	Dirty flags for each column value in this object.
std::vector< bool >	null_
	Null flags for each column value in this object.
std::vector< std::string >	data_
	Actual column data.
const Dv::Sql::Table::Ref	table_
	Table of this object.
Friends
bool	operator== (const Object &o1, const Object &o2)
	Test two objects for equality.
bool	operator!= (const Object &o1, const Object &o2)
	Test two objects for inequality.

Detailed Description

A class that represents a row in a database table or in a query result.

Objects represent an intermediate abstraction level between the low level interface provided by Dv::Sql::Command and the slightly higher level interface provided by Dv::Sql::Row. Nevertheless, objects may be useful for ad-hoc queries that e.g. apply sql aggregate functions.

: An instance of Object can be thought of as a vector of named columns, each column representing a value. In addition, a column my be null and/or dirty. A null column corresponds to a database NULL value. A dirty column value represents the assumption that the value was not retrieved from the database, but was set explicitly by the user.

: An object is also associated with a table, either a database table or a query table. The former have a name and correspond to the actual relations in the database. The latter have the empty string as name and correspond to the layout of a query result. An object's table is used to translate column names to indexes in the data array of the Object. If the table is a database table, it can also be used to e.g. insert, erase, etc. the object.

See also:: Dv::Sql::Row

Examples:: example-row.C.

Definition at line 45 of file object.h.

Member Typedef Documentation

typedef Dv::Sql::Set<Dv::Sql::Object> Dv::Sql::Object::Set

Type representing a set of rows.

Examples:: example-database.C.

Definition at line 48 of file object.h.

typedef Dv::shared_ptr<Object> Dv::Sql::Object::Ref

Type of (reference counted) pointer to Object.

Definition at line 389 of file object.h.

Constructor & Destructor Documentation

Dv::Sql::Object::Object	(	Dv::Sql::Db &	db,
		size_t	arity
	)

Create an empty object with a given arity.

Parameters:

	db	database connection to be used in further SQL statements with this object
	arity	number of column values that may be stored in this object

Dv::Sql::Object::Object ( Table::Ref table ) throw (std::logic_error)

Create an empty object associated with a given table.

The object will be copy the database connection from the table.

Parameters:

table

reference

Exceptions:

std::logic_error

if table is a null reference

See also:: Dv::Sql::Object::table

Dv::Sql::Object::Object	(	Table::Ref	table,
		SelectExp	select_exp,
		const std::string &	rest = `""`
	)			throw (std::logic_error, std::runtime_error)

Create an object containing the first row of a "select *" statement from a database table.

The select statement has the form

 select * from table->name() where select_exp rest

Parameters:

	table	to associate with this object
	select_exp	where clause of the query
	rest	of the query

Example

 // y is the youngest customer older than 21 (and younger than 100)
 Dv::Sql::Object y(customer, Customer::age > 21 && Customer::age < 100, "order by age");

Exceptions:

	std::logic_error	if the query fails or `table` is a null reference
	std::runtime_error	if the query does not return any answers

See also:: Dv::Sql::Object::table

Dv::Sql::Object::Object	(	Dv::Sql::Command &	q,
		unsigned int	r = `0`,
		const Table::Ref &	table = `Table::Ref(0)`
	)			throw (std::logic_error, std::runtime_error)

Create an object containing the r'th row of the answer of a query.

Example

 Dv::Sql::Command(db, "select amount from transaction", 
                   Transaction::acct_code = code, "order by amount");
 // retrieve the amount of the transaction on the account
 // with the largest amount
 Dv::Sql::Object max_amount(q, q.nrows()-1);

Parameters:

	q	query from whose answer the r'th row will be retrieved
	r	number of row in query answer to be retrieved
	table	optional database table to associate with this object If `table` is null, the object will be associated with the table of the query result.

Exceptions:

	std::logic_error	if execution of the query failed
	std::logic_error	if the table is non-null and does not have the same arity as the query answer
	std::runtime_error	if the query answer contains less than `r` rows

See also:: Dv::Sql::Command::table; Dv::Sql::Object::table

Dv::Sql::Object::Object	(	Dv::Sql::Db &	db,
		const std::string &	prefix,
		SelectExp	select_exp,
		const std::string &	rest = `""`
	)			throw (std::logic_error, std::runtime_error)

Create an object containing the first row of the answer of a query.

The query is composed by prefix followed by the select expression, followed by the optional rest. Example

 Object p(db, "select * from person where", Person::age > 3, "order by age");

Parameters:

	db	database connection to be used in further queries
	prefix	of query string
	select_exp	condition to follow "where"
	rest	of query string

Exceptions:

	std::logic_error	if mysql rejects the query
	std::runtime_error	if the query returns 0 rows

See also:: Dv::Sql::SelectExp; Dv::Sql::Command

Dv::Sql::Object::Object	(	Dv::Sql::Db &	db,
		const std::string &	query
	)			throw (std::logic_error, std::runtime_error)

Create an object containing the first row of the answer of a query for which the complete text is provided.

Example

 Object p(db, "select sum(amount)" + select_exp.from_where(db));

Parameters:

	db	database connection to be used in further queries
	query	text of query

Exceptions:

	std::logic_error	if mysql rejects the query
	std::runtime_error	if the query returns 0 rows

See also:: Dv::Sql::SelectExp; Dv::Sql::Command

Dv::Sql::Object::Object	(	const Dv::Sql::Object &	source,
		const Dv::Sql::Reference &	ref
	)			throw (std::runtime_error, std::logic_error)

Create an object from the result of following a reference.

Specifically, a query of the following form will be constructed:

 select * from ref.to_table where (match source_data according to ref)

Example

 const Dv::Sql::Reference acct_cust(
           Database::account, (cols = &Account::customer_id), 
           Database::customer, (cols = &Customer::id)
           );
 Object acct(..); 
 Object cust(acct, acct_cust); // customer owning the account
 // the executed query is
 // select * from customer where customer.id = account.customer_id

Exceptions:

	std::logic_error	if there is an error executing the query
	std::logic_error	if the arities of the `source` object does not match the arity of `ref.from_table`
	std::runtime_error	if the query does not return any answers

See also:: Dv::Sql::Reference; Dv::Sql::Table

virtual Dv::Sql::Object::~Object ( ) [virtual]

Destructor.

Member Function Documentation

bool Dv::Sql::Object::set	(	Dv::Sql::Command &	q,
		unsigned int	r = `0`
	)			throw (std::logic_error)

Set the column values of this object to those of the r'th row of the result of a query.

In addition, the object's table will be set to the table associated with the query, unless the object already has an associated database table. In the latter case, the arity of the query result must match the arity of the database table. The function will set all column values to dirty, and null values as appropriate.

Parameters:

	q	query from which the r'th answer row will be used to set the column values of this object
	r	the number of the row in the query result that will be used to set this object's column values.

Exceptions:

std::logic_error

if the object is associated with a database table and the arity of the query result does not match this table's arity.

See also:: Dv::Sql::Object::table

size_t Dv::Sql::Object::arity ( ) const [inline]

Number of column values in this object.

Returns:: the number of column values in this object

Definition at line 546 of file object.h.

References data_.

Referenced by get().

ColumnRef Dv::Sql::Object::operator[] ( size_t i ) throw (std::logic_error)

Return a reference to the i'th column in this object.

Parameters:

i

the number (0-based) of the column to refer to

Exceptions:

std::logic_error if i exceeds this object's arity

ColumnRef Dv::Sql::Object::operator[] ( const std::string & col_name ) throw (std::logic_error)

Return a reference to a named column in this object.

Parameters:

col_name

the name of the column to retrieve

Exceptions:

std::logic_error

if the table associated with this object does not contain a column with this name

See also:: Dv::Sql::Object::table

ColumnRef Dv::Sql::Object::operator[] ( const Table::Column & column ) throw (std::logic_error)

Return a reference to a column in this object.

Parameters:

column

the column to retrieve. Normally, a column from the table associated with this object.

Exceptions:

std::logic_error if column.index exceeds the arity of this object.

See also:: Dv::Sql::Object::table

virtual std::ostream& Dv::Sql::Object::print ( std::ostream & os ) const [virtual]

Print a readable representation of this object to a stream.

Parameters:

os

stream to print to.

Returns:: os

Dv::Sql::Db& Dv::Sql::Object::db ( ) const [inline]

The database connection of this object.

Returns:: the database connection of this object.

Definition at line 580 of file object.h.

References db_.

Object& Dv::Sql::Object::operator= ( const Object & o ) throw (std::logic_error)

Assignment operator.

Note that both objects must have the same associated table.

Parameters:

o

object to be assigned

Returns:: *this

Exceptions:

std::logic_error if the table of o does not match the table associated with this object.

See also:: Dv::Sql::Object::table

const Dv::Sql::Table::Ref Dv::Sql::Object::table ( ) const throw (std::logic_error)

Return a reference to the associated Dv::Sql::Table of this object.

There are two kinds of table: database tables and query tables. The former have a name and correspond to the actual relations in the database. The latter have the empty string as name and correspond to the layout of a query result. An object's table is used to translate column names to indexes in the data array of the Object. If the table is a database table, it can also be used to e.g. insert, erase, etc. the object.

Exceptions:

std::logic_error

if the object has no associated table.

See also:: Dv::Sql::Table

Referenced by get(), and set().

bool Dv::Sql::Object::has_db_table ( ) const

Is this object associated with a database table?

Returns:: true iff this object is associated with a database table

See also:: Dv::Sql::Object::table

Dv::Sql::Table::Ref Dv::Sql::Object::db_table ( ) const throw (std::logic_error)

Return a reference to the associated database Dv::Sql::Table of this object.

Exceptions:

std::logic_error

if the object has no associated table or if the associated table is a query table.

See also:: Dv::Sql::Object::table; Dv::Sql::Table

const Dv::Sql::Table::Column* Dv::Sql::Object::column ( size_t i ) const throw (std::logic_error)

Retrieve column information for this object.

Parameters:

i

the index (0-based) of the column for which info is to be retrieved

Returns:: a pointer to the column information, alwasy nonzero

Exceptions:

	std::logic_error	if the associated table is null
	std::logic_error	if `i` exceeds the object's arity.

size_t Dv::Sql::Object::match_first ( ) throw (std::logic_error)

Retrieve the first row, if any, that matches the dirty column values in this object.

Example

 Dv::Sql::Object cust;
 cust["name"] = "fred"; // will set dirty for "name"
 cust.match_first(); // first customer called "fred"

Returns:: the number of rows, possibly 0, retrieved by the underlying query.

Exceptions:

std::logic_error

iff the query execution failed

See also:: Object::dirty

bool Dv::Sql::Object::refresh ( ) throw (std::logic_error)

Retrieve the unique row, if any, that matches the primary key column values of this object.

The primary key information is obtained from the object's table.

Example

 Dv::Sql::Object cust;
 cust["name"] = "fred"; // will set dirty for "name"
 cust.match_first(); // first customer called "fred"
 cust["name"] = "jane";
 cust,refresh(); // name will be "fred" again

Returns:: true iff the object was found in the database

Exceptions:

std::logic_error

iff the query execution failed

Warning:: upon failure, dirty(c) iff c in primary key

See also:: Dv::Sql::Object::table

void Dv::Sql::Object::insert ( ) throw (std::runtime_error)

Insert the present object into a database, using an Sql 'insert' statement.

All non-null column values will be stored except for auto_inc columns. After the insert operation, the object will be refreshed thus causing auto_inc and default values to be available, as appropriate.

Example

 Dv::Sql::Object cust;
 cust.set("last_name",  last_nm)
     .set("first_name", first_nm)
     .set("birth_date", Dv::Util::Date(1970, 8, 20))
     .set("sex", "M")
     .set("email", "dvermeir@vub.ac.be")
     .insert();

Exceptions:

std::runtime_error

iff executing the insert statement failed.

See also:: Object::null(); Object::refresh(); Dv::Sql::Column::auto_inc

void Dv::Sql::Object::update ( ) throw (std::runtime_error)

Save dirty column values of an object to the database.

This function will execute an update statement using all dirty columns. The update statement will be executed on the row in the database that has the same primary key as the current object. See the Mysql documentation for the precise semantics.

Example

 Customer::Row cust(..);
 cust["id"] = cust_id;
 cust["last_name"] = new_name;
 cust.update();

Exceptions:

std::runtime_error

iff the corresponding sql statement failed.

Warning:: if there are no dirty columns, the operation is quietly canceled.

void Dv::Sql::Object::replace ( ) throw (std::runtime_error)

Save current state of the object to the database.

This function will execute a replace statement using all dirty columns as well as the columns in all unique keys. See the Mysql documentation for the precise semantics.

Exceptions:

std::runtime_error

iff the corresponding sql statement failed.

void Dv::Sql::Object::erase ( ) throw (std::runtime_error)

Remove the object from the database.

This function will execute a delete statement using the primary key columns. See the Mysql documentation for the precise semantics.

Exceptions:

std::runtime_error

iff the corresponding sql statement failed.

void Dv::Sql::Object::erase ( const Dv::Sql::SelectExp & exp ) const

Remove all objects from the table that satisfy some select expression.

The constructed sql statement uses the object's database and associated (database) table (only).

Dv::Sql::Command::Ref Dv::Sql::Object::match_query ( const std::string & rest = "" ) const throw (std::logic_error)

Create (and execute) a 'select' query out of the dirty columns of this object.

Parameters:

rest

optional suffix of the query

Returns:: a (reference counted) pointer to a newly allocated query

Exceptions:

std::logic_error

iff executing the query fails.

See also:: Object::match_first

Dv::Sql::SelectExp Dv::Sql::Object::match_exp ( ) const throw (std::logic_error)

Return a boolean expression that expresses a match with the dirty columns of this object.

Returns:: a boolean expression (a conjunction of equalities) asserting a match between dirty columns and their current values.

Example

 Dv::Sql::Table::Ref customer;
 Dv::Sql::Object cust(customer);
 cust["first_name"] = "fred";
 Dv::Sql::SelectExp e = cust.match_exp();
 // Get all customers called "fred" that are older than 21
 Dv::Sql::Object::Set freds(customer, e && (customer.age > 21));

Dv::Sql::Command::Ref Dv::Sql::Object::select	(	const Dv::Sql::SelectExp &	where_exp,
		const std::string &	rest = `""`
	)			const throw (std::logic_error)

Create (and execute) a query.

The query has the form

 select * from table_name where where_exp rest

Parameters:

	where_exp	to use in the query
	rest	of the text of the query

Exceptions:

std::logic_error

iff executing the query fails.

template<typename T >

Object& Dv::Sql::Object::set	(	size_t	i,
		const T &	t
	)			throw (std::logic_error) `[inline]`

Set a column value for this object.

Parameters:

	i	index (0-based) of the column
	t	value to store

Returns:: a reference to this object

Exceptions:

	std::logic_error	if `i` exceeds the object's arity
	std::logic_error	if `t` cannot be converted to a string using Dv::Util::tostring

Definition at line 801 of file object.h.

References set_data().

template<typename T >

Object& Dv::Sql::Object::set	(	const Table::Column &	c,
		const T &	t
	)			throw (std::logic_error) `[inline]`

Set a column value for this object.

Parameters:

	c	the column to set
	t	value to store

Returns:: a reference to this object

Exceptions:

	std::logic_error	if the index of `c` exceeds the object's arity
	std::logic_error	if `t` cannot be converted to a string using Dv::Util::tostring

Definition at line 815 of file object.h.

template<typename T >

Object& Dv::Sql::Object::set	(	const std::string &	col_name,
		const T &	t
	)			throw (std::logic_error) `[inline]`

Set a column value for this object.

Parameters:

	col_name	name of the column to set
	t	value to store

Returns:: a reference to this object

Exceptions:

	std::logic_error	if the object has no column with the given name
	std::logic_error	if `t` cannot be converted to a string using Dv::Util::tostring

See also:: Dv::Sql::Object::table

Definition at line 830 of file object.h.

References table().

template<typename T >

T Dv::Sql::Object::get ( size_t i ) const throw (std::logic_error) [inline]

Retrieve a column value for this object.

Parameters:

i

index (0-based) of the column value to retrieve

Returns:: the (converted) column value

Exceptions:

	std::logic_error	if `i` exceeds the object's arity
	std::logic_error	if the conversion from a string fails

Definition at line 843 of file object.h.

References arity(), and data_.

template<typename T >

T Dv::Sql::Object::get ( const Table::Column & c ) const throw (std::logic_error) [inline]

Retrieve a column value for this object.

Parameters:

c

the column to set

Returns:: the (converted) column value

Exceptions:

	std::logic_error	if the index of `c` exceeds the object's arity
	std::logic_error	if the conversion from a string fails

Definition at line 863 of file object.h.

template<typename T >

T Dv::Sql::Object::get ( const std::string & col_name ) const throw (std::logic_error) [inline]

Retrieve a column value for this object.

Parameters:

col_name

name of the column to retrieve

Returns:: the (converted) column value

Exceptions:

	std::logic_error	if the object has no column with the given name
	std::logic_error	if the conversion from a string fails

Definition at line 876 of file object.h.

References table().

Set::Ref Dv::Sql::Object::references ( const Reference & ref ) const throw (std::logic_error)

Return a reference to the set of objects obtained by following a given reference in reverse.

Example

 const Dv::Sql::Reference acct_cust(
           Database::account, (cols = &Account::customer_id), 
           Database::customer, (cols = &Customer::id)
           );
 Object cust(..); 
 // all accounts of this customer
 Object::Set::Ref accounts =  cust.references(acct_cust);

See also:: Dv::Sql::Set(const Source&,const Dv::Sql::Reference&)

Object& Dv::Sql::Object::copy_data	(	size_t	to_i,
		const Object &	from,
		size_t	from_i,
		bool	dirty
	)			throw (std::logic_error)

Copy a column value from another object to this one.

If the source column is null, the target column in this object will be null.

Parameters:

	to_i	index of target column in this object
	from	source object for copy
	from_i	index of source column in `source` object
	dirty	the dirty attribute of the target column will be set to this value

Exceptions:

std::logic_error

if one of the column indexes is out of range

See also:: Object::set_dirty

const std::string& Dv::Sql::Object::get_data ( const Table::Column & c ) const [inline]

Obtain the data value associated with this object.

This function does not do any checking, it also does not take into account the null status of this column.

Parameters:

i

index (0-based) of the column to retrieve the value of

Returns:: the value of the column

Definition at line 917 of file object.h.

References data_, Dv::Sql::Column::index(), and null().

Object& Dv::Sql::Object::set_data	(	size_t	i,
		const std::string &	value,
		bool	dirty
	)			throw (std::logic_error) `[protected]`

Set the value of column i in this object to value.

This function checks the validity of i.

Parameters:

	i	index (0-based) of the column to set the value of
	value	to store in the column
	dirty	new value of the dirty attribute of the column

Returns:: a reference to this object

Exceptions:

std::logic_error if i exceeds the object's arity

Referenced by Dv::Sql::Object::ColumnRef::operator=(), and set().

const std::string& Dv::Sql::Object::data ( size_t i ) const [inline, protected]

Obtain the data value associated with this object.

This function does not do any checking, it also does not take into account the null status of this column.

Parameters:

i

index (0-based) of the column to retrieve the value of

Returns:: the value of the column

Definition at line 945 of file object.h.

References data_.

void Dv::Sql::Object::set_null	(	size_t	i,
		bool	new_value
	)			throw () `[protected]`

Set the null status of a column.

This function does not verify the validity of its parameters.

Parameters:

	i	index (0-based) of the column to set the null status for
	new_value	new null status

Precondition:: i < arity()

bool Dv::Sql::Object::null ( size_t i ) const throw () [inline, protected]

Is a column value null?

Parameters:

i

index (0-based) of the column to retrieve the null status for

Returns:: true iff the column value is null

Precondition:: i < arity()

Definition at line 959 of file object.h.

References null_.

Referenced by get_data().

void Dv::Sql::Object::set_dirty	(	size_t	i,
		bool	new_value
	)			throw () `[protected]`

Set the dirty status of a column.

This function does not verify the validity of its parameters.

Parameters:

	i	index (0-based) of the column to set the dirty status for
	new_value	new dirty status

Precondition:: i < arity()

bool Dv::Sql::Object::dirty ( size_t i ) const throw () [inline, protected]

Is a column value dirty?

Parameters:

i

index (0-based) of the column to retrieve the dirty status for

Returns:: true iff the column value is dirty

Precondition:: i < arity()

Definition at line 973 of file object.h.

References dirty_.

void Dv::Sql::Object::set_table ( Dv::Sql::Table::Ref table ) throw (std::logic_error) [private]

Change the associated table of this object.

Note that if the object currently has a database table, this function will throw an exception.

Parameters:

table

new table

Exceptions:

std::logic_error

if the object is currently associated with a database table.

Friends And Related Function Documentation

bool operator==	(	const Object &	o1,
		const Object &	o2
	)			`[friend]`

Test two objects for equality.

The objects are equal iff they have the same associated table, their null_ arrays are equal and the corresponding non-null data_ values are also equal.

Parameters:

	o1	object to test for equality with `o2`
	o2	object to test for equality with `o1`

Returns:: true iff both objects are equal

See also:: Dv::Sql::Object::table

bool operator!=	(	const Object &	o1,
		const Object &	o2
	)			`[friend]`

Test two objects for inequality.

The objects are equal iff they have the same associated table, their null_ arrays are equal and the corresponding non-null data_ values are also equal.

Parameters: