null.hpp

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#pragma once
 
/// @file userver/storages/postgres/null.hpp
/// @brief NULL type
 
#include <userver/storages/postgres/io/nullable_traits.hpp>
#include <userver/storages/postgres/io/traits.hpp>
#include <userver/storages/postgres/io/type_mapping.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace storages::postgres {
 
/// @brief Type to represent a null value
template <typename T>
struct Null {};
 
/// @brief Template variable to use with query parameters.
/// @code
/// trx->Execute("update a_table set val = $1 where val = $2", null<int>, 0)
/// @endcode
template <typename T>
inline constexpr Null<T> null{};
 
namespace io {
namespace traits {
 
template <typename T>
struct IsNullable<Null<T>> : std::true_type {};
 
template <typename T>
struct GetSetNull<Null<T>> {
    inline static bool IsNull(const Null<T>&) { return true; }
    static void SetNull(T&) {}
};
 
template <typename T>
struct IsMappedToPg<Null<T>> : IsMappedToPg<T> {};
template <typename T>
struct IsSpecialMapping<Null<T>> : IsMappedToPg<T> {};
 
}  // namespace traits
 
template <typename T>
struct CppToPg<Null<T>> : CppToPg<T> {};
 
template <typename T>
struct BufferFormatter<Null<T>> {
    explicit BufferFormatter(const Null<T>&) {}
 
    template <typename Buffer>
    void operator()(const UserTypes&, Buffer&) const {}
};
 
}  // namespace io
 
}  // namespace storages::postgres
 
USERVER_NAMESPACE_END