Functions

Description

Query-related functions.

Functions
template<typename BinaryQueryConvertible , typename OidMap , typename Allocator = std::allocator<char>>
binary_query	ozo::to_binary_query (const BinaryQueryConvertible &query, const OidMap &oid_map, const Allocator &allocator=Allocator{})
	Convert a query object to the binary representation. More...
template<typename T >
constexpr auto	ozo::to_const_char (const T &text) noexcept
	Convert QueryText to const char*. More...
template<typename Query >
constexpr auto	ozo::get_query_text (Query &&query)
	Get the query text object. More...
template<typename T >
constexpr auto	ozo::get_query_params (Query &&query)
	Get the query parameters. More...
template<class QueryText , class ... Params>
constexpr auto	ozo::make_query (QueryText &&text, Params &&...params)
	Construct built-in Query implementation object. More...

Function Documentation

get_query_params()

template<typename T >

constexpr auto ozo::get_query_params ( Query &&  query )

constexpr

Get the query parameters.

Provides read-only access to query parameters. This function invokes ozo::get_query_params_impl::apply() and should be customized via ozo::get_query_params_impl specialization.

Customization point

This is one of two points (see also ozo::get_query_text()) which should be used to support your own query type in the library. E.g.:

namespace ozo {
 
template <>
struct get_query_params_impl<my_ns::my_query> {
    static decltype(auto) apply(const my_ns::my_query& q) {
        return boost::hana::make_tuple(q.param1, q.param2, q.param3);
    }
};
 
} // namespace ozo

Parameters

query

— query object

Returns

#HanaSequence — tuple with query parameters

See also

ozo::get_query_text

get_query_text()

template<typename Query >

constexpr auto ozo::get_query_text ( Query &&  query )

constexpr

Get the query text object.

Provides read-only access to a query text with SQL statement. This function invokes ozo::get_query_text_impl::apply() and should be customized via ozo::get_query_text_impl specialization.

Customization point

This is one of two points (see also ozo::get_query_params()) which should be used to support your own query type in the library. E.g.:

namespace ozo {
 
template <>
struct get_query_text_impl<my_ns::my_query> {
    static decltype(auto) apply(const my_ns::my_query& q) {
        return q.get_text();
    }
};
 
} // namespace ozo

Parameters

query

— query object

Returns

QueryText — query text with single SQL statement

See also

ozo::get_query_params

make_query()

template<class QueryText , class ... Params>

constexpr auto ozo::make_query ( QueryText &&  text, Params &&...  params  )

constexpr

Construct built-in Query implementation object.

Construct built-in Query implementation object from specified text and variadic parameters.

Note

Currently no compile-time parameters validation provided by this function, the validation would be made in run-time only.

Example

auto query = ozo::make_query(
    "SELECT id, name FROM users WHERE credit > $1 AND rating > $2;",
    min_credit, min_rating);

Parameters

text	— query text implementation with PostgreSQL native markup with variable place holder format is $n, there n - parameter position in the params begining from 1.
params	— query parameters

Returns

Query object

to_binary_query()

template<typename BinaryQueryConvertible , typename OidMap , typename Allocator = std::allocator<char>>

binary_query ozo::to_binary_query	(	const BinaryQueryConvertible &	query,
		const OidMap &	oid_map,
		const Allocator &	allocator = Allocator{}
	)

Convert a query object to the binary representation.

This function provides an ability to convert a query object to the protocol compatible binary representation to send it to the PostgreSQL database. A user may call this function to reuse the binary_query and eliminate unnecessarily conversion of the query object to its binary representation each operation. E.g., this may be useful with the failover micro-framework.

Parameters

query	— a query object to convert to the binary representation.
oid_map	— OidMap to type OIDs for the binary representation.
allocator	— allocator to use for the data of ozo::binary_query.

Returns

ozo::binary_query — the binary representation.

to_const_char()

template<typename T >

constexpr auto ozo::to_const_char ( const T &  text )

constexprnoexcept

Convert QueryText to const char*.

Convert QueryText to const char* for futher transfer to a database. This function invokes ozo::to_const_char_impl::apply() and should be customized via ozo::to_const_char_impl specialization. Built-in support for types:

• const char*,
• std::string,
• std::string_view,
• boost::hana::string.

Customization point

This point should be used to add support for your own query text type. E.g.:

namespace ozo {
 
template <>
struct to_const_char_impl<my_ns::my_string> {
    static decltype(auto) apply(const my_ns::my_string& text) noexcept {
        return text.get_data();
    }
};
 
} // namespace ozo

Note

ozo::to_const_char_impl::apply() should be noexcept.

Parameters

text	— query text to transform to const char*

Returns

const char*