1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114 | #pragma once
#include <kooling/json/json.h>
#include <plog/Log.h>
#include <cstddef>
#include <string>
#include <string_view>
#include <utility>
#include <pqxx/pqxx>
#include <pqxx/version>
namespace kooling::database {
struct config
{
std::string name;
std::string host;
int port;
std::string user;
std::string pass;
};
NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(config, name, host, port, user, pass);
static constexpr int pqxx_version_number{ PQXX_VERSION_MAJOR * 100 + PQXX_VERSION_MINOR };
template<typename... Ts>
struct params : std::tuple<std::decay_t<Ts>...>
{
params(Ts... ts)<--- Struct 'params' has a constructor with 1 argument that is not explicit. [+]Struct 'params' has a constructor with 1 argument that is not explicit. Such, so called "Converting constructors", should in general be explicit for type safety reasons as that prevents unintended implicit conversions.
: std::tuple<std::decay_t<Ts>...>{ std::forward<Ts>(ts)... }
{}
pqxx::params to_pqxx_params() const
{
pqxx::params ps;
append<0>(ps);
return ps;
};
private:
template<std::size_t Nth>
void append(pqxx::params& ps) const
{
if constexpr (Nth < sizeof...(Ts))
{
ps.append(std::get<Nth>(*this));
append<Nth + 1>(ps);
}
}
};
template<typename... Ts>
params(Ts...) -> params<std::decay_t<Ts>...>;
class database
{
public:
explicit database(const config&conf);
explicit database(std::string_view conn_string);
template<typename F>
bool query(std::string_view q, F&& f)
{
return query(q, params<>{}, std::forward<F>(f));
}
template<typename F, typename... Params>
bool query(std::string_view q, const params<Params...>& ps, F&& f)
{
return query(std::make_index_sequence<sizeof...(Params)>{}, q, ps, std::forward<F>(f));
}
std::string quote(std::string_view str) const
{
return d_connection.quote(str);
}
std::string quote_table(std::string_view table_name) const
{
return d_connection.quote_table(table_name);
}
private:
template<typename F, typename P, std::size_t... Is>
bool query(std::index_sequence<Is...>, std::string_view q, const P& ps, F&& f)
{
try
{
pqxx::nontransaction txn{ d_connection };
if constexpr (pqxx_version_number > 708)
{
txn.for_query(pqxx::zview{ q }, std::forward<F>(f), ps.to_pqxx_params());
}
else
{
txn.exec_params(pqxx::zview{ q }, std::get<Is>(ps)...).for_each(std::forward<F>(f));
}
}
catch (const std::exception& exn)
{
PLOG_ERROR << "database error: " << exn.what();
return false;
}
return true;
}
private:
pqxx::connection d_connection;
};
} // namespace kooling::database
|