16 #include "pqxx/compiler-public.hxx"
17 #include "pqxx/internal/compiler-internal-pre.hxx"
21 #include "pqxx/array.hxx"
22 #include "pqxx/composite.hxx"
23 #include "pqxx/result.hxx"
24 #include "pqxx/strconv.hxx"
25 #include "pqxx/types.hxx"
44 "Do not construct fields yourself. Get them from the row.")]]
field(
row const &r,
row_size_type c) noexcept;
48 "Do not construct fields yourself. Get them from the row.")]]
field() =
72 [[nodiscard]] PQXX_PURE
bool operator==(
field const &)
const;
79 return not operator==(rhs);
88 [[nodiscard]] PQXX_PURE
char const *name()
const;
91 [[nodiscard]] oid PQXX_PURE type()
const;
94 [[nodiscard]] PQXX_PURE oid table()
const;
108 [[nodiscard]] PQXX_PURE std::string_view
view()
const
110 return std::string_view(c_str(), size());
123 [[nodiscard]] PQXX_PURE
char const *c_str()
const;
126 [[nodiscard]] PQXX_PURE
bool is_null() const noexcept;
129 [[nodiscard]] PQXX_PURE size_type size() const noexcept;
136 auto to(T &obj) const -> typename std::enable_if_t<
137 (not std::is_pointer<T>::value or std::is_same<T,
char const *>::value),
146 auto const bytes{c_str()};
172 template<
typename T>
bool operator>>(T &obj)
const {
return to(obj); }
186 auto to(T &obj, T
const &default_value)
const ->
typename std::enable_if_t<
187 (not std::is_pointer<T>::value or std::is_same<T, char const *>::value),
194 obj = from_string<T>(this->view());
202 template<
typename T> T
as(T
const &default_value)
const
205 return default_value;
207 return from_string<T>(this->view());
216 template<
typename T> T
as()
const
227 return from_string<T>(this->view());
235 template<
typename T,
template<
typename>
class O = std::optional>
236 constexpr O<T>
get()
const
272 template<>
inline bool field::to<std::string>(std::string &obj)
const
276 obj = std::string{view()};
282 inline bool field::to<std::string>(
283 std::string &obj, std::string
const &default_value)
const
289 obj = std::string{view()};
300 template<>
inline bool field::to<char const *>(
char const *&obj)
const
309 template<>
inline bool field::to<std::string_view>(std::string_view &obj)
const
319 inline bool field::to<std::string_view>(
320 std::string_view &obj, std::string_view
const &default_value)
const
331 template<>
inline std::string_view field::as<std::string_view>()
const
341 inline std::string_view
342 field::as<std::string_view>(std::string_view
const &default_value)
const
344 return is_null() ? default_value : view();
348 template<>
inline bool field::to<zview>(
zview &obj)
const
358 inline bool field::to<zview>(
zview &obj,
zview const &default_value)
const
369 template<>
inline zview field::as<zview>()
const
378 template<>
inline zview field::as<zview>(
zview const &default_value)
const
384 template<
typename CHAR =
char,
typename TRAITS = std::
char_traits<CHAR>>
399 virtual int sync()
override {
return traits_type::eof(); }
403 return traits_type::eof();
407 return traits_type::eof();
413 field const &m_field;
417 auto g{
static_cast<char_type *
>(
const_cast<char *
>(m_field.
c_str()))};
418 this->setg(g, g, g + std::size(m_field));
419 return int_type(std::size(m_field));
433 template<
typename CHAR =
char,
typename TRAITS = std::
char_traits<CHAR>>
436 using super = std::basic_istream<CHAR, TRAITS>;
477 template<
typename CHAR>
478 inline std::basic_ostream<CHAR> &
481 s.write(value.
c_str(), std::streamsize(std::size(value)));
502 return from_string<T>(value.
view());
515 inline std::nullptr_t from_string<std::nullptr_t>(
field const &value)
519 "Extracting non-null field into nullptr_t variable."};
525 template<> PQXX_LIBEXPORT std::string
to_string(field
const &value);
528 #include "pqxx/internal/compiler-internal-post.hxx"
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:26
int row_size_type
Number of fields in a row of database data.
Definition: types.hxx:30
std::size_t field_size_type
Number of bytes in a field of database data.
Definition: types.hxx:36
void parse_composite(pqxx::internal::encoding_group enc, std::string_view text, T &...fields)
Parse a string representation of a value of a composite type.
Definition: composite.hxx:33
std::string to_string(field const &value)
Convert a field to a string.
Definition: result.cxx:507
std::basic_ostream< CHAR > & operator<<(std::basic_ostream< CHAR > &s, field const &value)
Write a result field to any type of stream.
Definition: field.hxx:479
bool is_null(TYPE const &value) noexcept
Is value null?
Definition: strconv.hxx:357
T from_string(field const &value)
Convert a field's value to type T.
Definition: field.hxx:490
void throw_null_conversion(std::string const &type)
Definition: strconv.cxx:243
Low-level array parser.
Definition: array.hxx:47
Value conversion failed, e.g. when converting "Hello" to int.
Definition: except.hxx:179
Reference to a field in a result set.
Definition: field.hxx:34
row_size_type col() const noexcept
Definition: field.hxx:258
PQXX_PURE size_type size() const noexcept
Return number of bytes taken up by the field's value.
Definition: field.cxx:72
T as(T const &default_value) const
Return value as object of given type, or default value if null.
Definition: field.hxx:202
row_size_type m_col
Definition: field.hxx:264
auto to(T &obj, T const &default_value) const -> typename std::enable_if_t<(not std::is_pointer< T >::value or std::is_same< T, char const * >::value), bool >
Read value into obj; or if null, use default value and return false.
Definition: field.hxx:186
constexpr O< T > get() const
Return value wrapped in some optional type (empty for nulls).
Definition: field.hxx:236
result const & home() const noexcept
Definition: field.hxx:256
field_size_type size_type
Definition: field.hxx:36
bool operator>>(T &obj) const
Read value into obj; or leave obj untouched and return false if null.
Definition: field.hxx:172
field()=default
Constructor. Do not call this yourself; libpqxx will do it for you.
array_parser as_array() const
Parse the field as an SQL array.
Definition: field.hxx:248
PQXX_PURE char const * c_str() const
Read as plain C string.
Definition: field.cxx:60
result::size_type idx() const noexcept
Definition: field.hxx:257
T as() const
Return value as object of given type, or throw exception if null.
Definition: field.hxx:216
PQXX_PURE bool operator!=(field const &rhs) const
Byte-by-byte comparison (all nulls are considered equal)
Definition: field.hxx:77
PQXX_PURE row_size_type num() const
Return row number. The first row is row 0, the second is row 1, etc.
Definition: field.hxx:97
bool composite_to(T &...fields) const
Read field as a composite value, write its components into fields.
Definition: field.hxx:158
PQXX_PURE bool is_null() const noexcept
Is this field's value null?
Definition: field.cxx:66
PQXX_PURE std::string_view view() const
Read as string_view, or an empty one if null.
Definition: field.hxx:108
Definition: field.hxx:386
TRAITS traits_type
Definition: field.hxx:389
typename traits_type::off_type off_type
Definition: field.hxx:392
field_streambuf(field const &f)
Definition: field.hxx:396
virtual pos_type seekoff(off_type, seekdir, openmode) override
Definition: field.hxx:401
virtual pos_type seekpos(pos_type, openmode) override
Definition: field.hxx:405
std::ios::openmode openmode
Definition: field.hxx:393
virtual int_type overflow(int_type) override
Definition: field.hxx:409
typename traits_type::pos_type pos_type
Definition: field.hxx:391
virtual int sync() override
Definition: field.hxx:399
typename traits_type::int_type int_type
Definition: field.hxx:390
virtual int_type underflow() override
Definition: field.hxx:410
CHAR char_type
Definition: field.hxx:388
std::ios::seekdir seekdir
Definition: field.hxx:394
Input stream that gets its data from a result field.
Definition: field.hxx:435
TRAITS traits_type
Definition: field.hxx:440
basic_fieldstream(field const &f)
Definition: field.hxx:445
typename traits_type::pos_type pos_type
Definition: field.hxx:442
typename traits_type::off_type off_type
Definition: field.hxx:443
typename traits_type::int_type int_type
Definition: field.hxx:441
CHAR char_type
Definition: field.hxx:439
Result set containing data returned by a query or command.
Definition: result.hxx:71
result_size_type size_type
Definition: result.hxx:73
Reference to one row in a result.
Definition: row.hxx:46
Traits describing a type's "null value," if any.
Definition: strconv.hxx:91
static TYPE null()
Return a null value.
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:40