pqxx::row Class Reference

Reference to one row in a result. More...

Inheritance diagram for pqxx::row:

Collaboration diagram for pqxx::row:

Public Types
using	size_type = row_size_type
using	difference_type = row_difference_type
using	const_iterator = const_row_iterator
using	iterator = const_iterator
using	reference = field
using	pointer = const_row_iterator
using	const_reverse_iterator = const_reverse_row_iterator
using	reverse_iterator = const_reverse_iterator

Public Member Functions
	row (row &&) noexcept=default
	row (row const &) noexcept=default
row &	operator= (row const &) noexcept=default
row &	operator= (row &&) noexcept=default
Comparison
PQXX_PURE bool	operator== (row const &) const noexcept
bool	operator!= (row const &rhs) const noexcept
const_iterator	begin () const noexcept
const_iterator	cbegin () const noexcept
const_iterator	end () const noexcept
const_iterator	cend () const noexcept
Field access
reference	front () const noexcept
reference	back () const noexcept
const_reverse_row_iterator	rbegin () const noexcept
const_reverse_row_iterator	crbegin () const noexcept
const_reverse_row_iterator	rend () const noexcept
const_reverse_row_iterator	crend () const noexcept
reference	operator[] (size_type) const noexcept
reference	operator[] (zview col_name) const
reference	at (size_type) const
reference	at (zview col_name) const
constexpr size_type	size () const noexcept
constexpr result::size_type	rownumber () const noexcept
	Row number, assuming this is a real row and not end()/rend().

Column information
class	const_row_iterator
class	result
template<typename... T>
class	pqxx::internal::result_iter
class	field
result	m_result
	Result set of which this is one row.
result::size_type	m_index = 0
	Row number.
size_type	m_begin = 0
	First column in slice. This row ignores lower-numbered columns.
size_type	m_end = 0
	End column in slice. This row only sees lower-numbered columns.
size_type	column_number (zview col_name) const
	Number of given column (throws exception if it doesn't exist).
oid	column_type (size_type) const
	Return a column's type.
oid	column_type (zview col_name) const
	Return a column's type.
oid	column_table (size_type col_num) const
	What table did this column come from?
oid	column_table (zview col_name) const
	What table did this column come from?
size_type	table_column (size_type) const
	What column number in its table did this result column come from?
size_type	table_column (zview col_name) const
	What column number in its table did this result column come from?
constexpr result::size_type	num () const noexcept
template<typename Tuple >
void	to (Tuple &t) const
	Extract entire row's values into a tuple.
template<typename... TYPE>
std::tuple< TYPE... >	as () const
	Extract entire row's values into a tuple.
void	swap (row &) noexcept
row	slice (size_type sbegin, size_type send) const
PQXX_PURE bool	empty () const noexcept
	Is this a row without fields? Can only happen to a slice.
	row (result r, result_size_type index, size_type cols) noexcept
void	check_size (size_type expected) const
	Throw usage_error if row size is not expected.
template<typename TUPLE >
TUPLE	as_tuple () const
	Convert to a given tuple of values, don't check sizes.
template<typename Tuple >
void	convert (Tuple &t) const
	Convert entire row to tuple fields, without checking row size.

Detailed Description

Reference to one row in a result.

A row represents one row (also called a row) in a query result set. It also acts as a container mapping column numbers or names to field values (see below):

cout << row["date"].c_str() << ": " << row["name"].c_str() << endl;

The row itself acts like a (non-modifyable) container, complete with its own const_iterator and const_reverse_iterator.

Constructor & Destructor Documentation

row()

pqxx::row::row ( result  r, result_size_type  index, size_type  cols  )

protectednoexcept

Implementation of the pqxx::result class and support classes.

pqxx::result represents the set of result rows from a database query.

Copyright (c) 2000-2025, Jeroen T. Vermeulen.

See COPYING for copyright license. If you did not receive a file called COPYING with this source code, please notify the distributor of this mistake, or contact the author.

Member Function Documentation

as()

template<typename... TYPE>

std::tuple< TYPE... > pqxx::row::as ( ) const

inline

Extract entire row's values into a tuple.

Converts to the types of the tuple's respective fields.

The types must have conversions from PostgreSQL's text format defined; see Supporting additional data types.

Exceptions

usage_error

If the number of columns in the row does not match the number of fields in t.

as_tuple()

template<typename TUPLE >

TUPLE pqxx::row::as_tuple ( ) const

inlineprotected

Convert to a given tuple of values, don't check sizes.

We need this for cases where we have a full tuple of field types, but not a parameter pack.

at()

pqxx::field pqxx::row::at

(

zview

col_name

)

const

Address field by name.

Warning

This is much slower than indexing by number, or iterating.

operator[]()

pqxx::row::reference pqxx::row::operator[]

(

zview

col_name

)

const

Address field by name.

Warning

This is much slower than indexing by number, or iterating.

slice()

pqxx::row pqxx::row::slice	(	size_type	sbegin,
		size_type	send
	)		const

Produce a slice of this row, containing the given range of columns.

Deprecated:

I haven't heard of anyone caring about row slicing at all in at least the last 15 years. Yet it adds complexity, so unless anyone files a bug explaining why they really need this feature, I'm going to remove it. Even if they do, the feature may need an update.

The slice runs from the range's starting column to the range's end column, exclusive. It looks just like a normal result row, except slices can be empty.

table_column()

pqxx::row::size_type pqxx::row::table_column

(

size_type

col_num

)

const

What column number in its table did this result column come from?

A meaningful answer can be given only if the column in question comes directly from a column in a table. If the column is computed in any other way, a logic_error will be thrown.

Parameters

col_num

a zero-based column number in this result set

Returns

a zero-based column number in originating table

to()

template<typename Tuple >

void pqxx::row::to ( Tuple &  t ) const

inline

Extract entire row's values into a tuple.

Converts to the types of the tuple's respective fields.

The types in the tuple must have conversions from PostgreSQL's text format defined; see Supporting additional data types.

Exceptions

usage_error

If the number of columns in the row does not match the number of fields in t.

Member Data Documentation

m_index

result::size_type pqxx::row::m_index = 0

protected

Row number.

You'd expect this to be unsigned, but due to the way reverse iterators are related to regular iterators, it must be allowed to underflow to -1.

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

• /home/docs/checkouts/readthedocs.org/user_builds/libpqxx/checkouts/stable/include/pqxx/row.hxx
• /home/docs/checkouts/readthedocs.org/user_builds/libpqxx/checkouts/stable/src/row.cxx