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# JSON_DISABLE_ENUM_SERIALIZATION

    #define JSON_DISABLE_ENUM_SERIALIZATION /* value */

When defined to `1`, default serialization and deserialization functions for enums are excluded and have to be provided by the user, for example, using `NLOHMANN_JSON_SERIALIZE_ENUM` (see arbitrary type conversions for more details).

Parsing or serializing an enum will result in a compiler error.

This works for both unscoped and scoped enums.

## Default definition

The default value is `0`.

    #define JSON_DISABLE_ENUM_SERIALIZATION 0

## Notes

CMake option

Enum serialization can also be controlled with the CMake option `JSON_DisableEnumSerialization` (`OFF` by default) which defines `JSON_DISABLE_ENUM_SERIALIZATION` accordingly.

## Examples

Example 1: Disabled behavior

The code below forces the library not to create default serialization/deserialization functions `from_json` and `to_json`, meaning the code below does not compile.

    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

    using json = nlohmann::json;

    enum class Choice
    {
        first,
        second,
    };

    int main()
    {
        // normally invokes to_json serialization function but with JSON_DISABLE_ENUM_SERIALIZATION defined, it does not
        const json j = Choice::first;

        // normally invokes from_json parse function but with JSON_DISABLE_ENUM_SERIALIZATION defined, it does not
        Choice ch = j.get<Choice>();
    }

Example 2: Serialize enum macro

The code below forces the library not to create default serialization/deserialization functions `from_json` and `to_json`, but uses `NLOHMANN_JSON_SERIALIZE_ENUM` to parse and serialize the enum.

    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

    using json = nlohmann::json;

    enum class Choice
    {
        first,
        second,
    };

    NLOHMANN_JSON_SERIALIZE_ENUM(Choice,
    {
        { Choice::first, "first" },
        { Choice::second, "second" },
    })

    int main()
    {
        // uses user-defined to_json function defined by macro
        const json j = Choice::first;

        // uses user-defined from_json function defined by macro
        Choice ch = j.get<Choice>();
    }

Example 3: User-defined serialization/deserialization functions

The code below forces the library not to create default serialization/deserialization functions `from_json` and `to_json`, but uses user-defined functions to parse and serialize the enum.

    #define JSON_DISABLE_ENUM_SERIALIZATION 1
    #include <nlohmann/json.hpp>

    using json = nlohmann::json;

    enum class Choice
    {
        first,
        second,
    };

    void from_json(const json& j, Choice& ch)
    {
        auto value = j.get<std::string>();
        if (value == "first")
        {
            ch = Choice::first;
        }
        else if (value == "second")
        {
            ch = Choice::second;
        }
    }

    void to_json(json& j, const Choice& ch)
    {
        auto value = j.get<std::string>();
        if (value == "first")
        {
            ch = Choice::first;
        }
        else if (value == "second")
        {
            ch = Choice::second;
        }
    }

    int main()
    {
        // uses user-defined to_json function
        const json j = Choice::first;

        // uses user-defined from_json function
        Choice ch = j.get<Choice>();
    }

## See also

- `NLOHMANN_JSON_SERIALIZE_ENUM`

## Version history

- Added in version 3.11.0.

Last update: July 31, 2022
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