Niels Lohmann
63c10a51fc
* Review and extend the documentation, and check it in CI A review of all documentation pages found factual errors, dead links, missing cross-references, and gaps in examples. This fixes them and adds checks so the same problems are caught automatically. Fixes: - wrong signatures and version histories (operator!= C++20 member, binary() subtype type, get<PointerType>(), JSON_NO_THREAD_LOCAL, ...) - stale descriptions (number parsing since #5283, UBJSON table, SAX example that no longer compiled, tsl::ordered_map advice) - dead internal and external links; repology.org badges (the domain is suspended) replaced by badges that query the registries directly - deprecation notes link the migration guide; the guide itself fixed Additions: - "See also" sections, cross-references, 25 runnable examples, 12 Mermaid diagrams, new API pages for json_pointer::operator<=> and byte_container_with_subtype::operator==/!= - landing page, guides for untrusted input and performance - "unreleased" badge after versions newer than the latest release Checks: - strict documentation build (broken links/anchors fail it); CI and the publish workflow fetch the full history the build needs - weekly external link check, Mermaid syntax check in CI - check_structure.py: example titles, heading levels, alt texts, header links, docset index coverage; its unused-example check works again - all examples produce the same output on every platform Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Keep the customer links that could not be fixed A dead link on the customers page is still the evidence of where the use of the library was documented. Keep the original URLs of the entries without a working replacement (Marne, Cisco Webex Desk Camera, Philips Hue, CyberArk) and exclude exactly these URLs from the link check. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Correct the duplicate-key recipe's claim about SAX positions The SAX interface's key() receives no position either; only parse_error() does. Also note that the recipe does not report the path to the repeated key (see discussion #5085). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Say the library is available as a single header and mention json_fwd.hpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Correct documentation errors found while hunting for bugs - patch/patch_inplace: list the JSON pointer errors parse_error.106-109 and out_of_range.402/404, and quote the actual parse_error.105 message. - unflatten: list parse_error.106/107/108 and out_of_range.404. - to_bson: list out_of_range.415 (binary subtype above 255) and note that 412 and 415 are new in 3.13.0. - to_string: state that string_t must be convertible to std::string, also in the StringType requirements table. - JSON Lines: a `while (input >> j)` loop also throws after the last value for concatenated JSON values; show a loop that works for both. - BON8: a string gets 0xFF only if nothing follows it in the message; a string at the end of an array or object is ended by 0xFE. - custom_string_type.hpp: add operator+=(char), which the "Always required" list asks for (json_pointer::to_string, flatten, unflatten, and diff did not compile), and an ADL int_to_string for diff and items. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Cache the release headers with functools.lru_cache Codacy (Pylint) flagged the mutable default argument that header() used as its cache. functools.lru_cache keeps the same memoization without it. The script's output is unchanged. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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NLOHMANN_JSON_SERIALIZE_ENUM
#define NLOHMANN_JSON_SERIALIZE_ENUM(type, conversion...)
By default, enum values are serialized to JSON as integers. In some cases, this could result in undesired behavior. If an enum is modified or re-ordered after data has been serialized to JSON, the later deserialized JSON data may be undefined or a different enum value than was originally intended.
The NLOHMANN_JSON_SERIALIZE_ENUM allows to define a user-defined serialization for every enumerator.
Parameters
type(in)- name of the enum to serialize/deserialize
conversion(in)- a pair of an enumerator and a JSON serialization; arbitrary pairs can be given as a comma-separated list
Default definition
The macro adds two functions to the namespace which take care of the serialization and deserialization:
template<typename BasicJsonType>
inline void to_json(BasicJsonType& j, const type& e);
template<typename BasicJsonType>
inline void from_json(const BasicJsonType& j, type& e);
Notes
!!! info "Prerequisites"
The macro must be used inside the namespace of the enum.
!!! important "Important notes"
- When using [`get<ENUM_TYPE>()`](../basic_json/get.md), undefined JSON values will default to the first specified
conversion. Select this default pair carefully. See example 1 below.
- If an enum or JSON value is specified in multiple conversions, the first matching conversion from the top of the
list will be returned when converting to or from JSON. See example 2 below.
Examples
??? example "Example: Basic usage"
The example shows how `NLOHMANN_JSON_SERIALIZE_ENUM` can be used to serialize/deserialize both classical enums and
C++11 enum classes:
```cpp hl_lines="16 17 18 19 20 21 22 29 30 31 32 33"
--8<-- "examples/nlohmann_json_serialize_enum.cpp"
```
Output:
```json
--8<-- "examples/nlohmann_json_serialize_enum.output"
```
??? example "Example: Multiple conversions for one enumerator"
The example shows how to use multiple conversions for a single enumerator. In the example, `Color::red` will always
be *serialized* to `"red"`, because the first occurring conversion. The second conversion, however, offers an
alternative *deserialization* from `"rot"` to `Color::red`.
```cpp hl_lines="17"
--8<-- "examples/nlohmann_json_serialize_enum_2.cpp"
```
Output:
```json
--8<-- "examples/nlohmann_json_serialize_enum_2.output"
```
See also
Version history
Added in version 3.4.0.