Reflection helpers

Namespace: usub::uredis::reflect.

These helpers let you map C++ aggregates to Redis hashes using ureflect.

namespace usub::uredis::reflect {

template <class T>
    requires std::is_aggregate_v<std::remove_cvref_t<T>>
task::Awaitable<RedisResult<int64_t>> hset_struct(
    RedisClient& client,
    std::string_view key,
    const T& value);

template <class T>
    requires std::is_aggregate_v<std::remove_cvref_t<T>>
task::Awaitable<RedisResult<std::optional<T>>> hget_struct(
    RedisClient& client,
    std::string_view key);

} // namespace usub::uredis::reflect

Supported field types

Internally it converts fields to/from strings using detail::to_redis_string_impl / from_redis_string_impl.

Out of the box it handles:

• std::string, std::string_view, const char*
• bool (stored as "0" / "1")
• integral types (via std::to_chars / std::from_chars)
• floating point types (via std::to_string / std::stof / std::stod)
• std::optional<T> for any supported T

Example

#include "uredis/RedisClient.h"
#include "uredis/RedisReflect.h"

struct User
{
    int64_t id;
    std::string name;
    bool active;
    std::optional<int64_t> age;
};

task::Awaitable<void> reflect_example()
{
    RedisConfig cfg;
    cfg.host = "127.0.0.1";
    cfg.port = 15100;

    RedisClient client{cfg};
    co_await client.connect();

    using namespace usub::uredis::reflect;

    User u{.id = 42, .name = "Kirill", .active = true, .age = 30};

    auto hset_res = co_await hset_struct(client, "user:42", u);

    auto loaded = co_await hget_struct<User>(client, "user:42");
    if (loaded && loaded.value().has_value())
    {
        const User& u2 = *loaded.value();
        // use u2
    }

    co_return;
}

On the Redis side this is equivalent to:

HSET user:42 id 42 name "Kirill" active 1 age 30
HGETALL user:42

Behavior

• hset_struct:

  • Uses ureflect::for_each_field to iterate fields.
  • For each field (name, value) pushes name and string(value) into args.
  • Executes HSET key field1 value1 field2 value2 ....
  • Returns Redis integer reply (number of new fields added).

• hget_struct:

  • Calls HGETALL key.
  • Builds a std::unordered_map<std::string, std::string>.

  • For each struct field:

    • Looks up map by field name.

    • Converts string into field type with from_redis_string.

      • Returns std::optional<T>:

    • std::nullopt if hash does not exist or is empty.

    • T filled with decoded fields otherwise.