- Make the iterator range illustrations legible in dark mode (prefers-color-scheme
rules inside the SVGs).
- Add a "Byte layout" section with a color-coded byte table to each binary format
page (BJData, BON8, BSON, CBOR, MessagePack, UBJSON), and highlight the smallest
size per file in the comparison table.
- Add "See also" sections to the overview pages that lacked one.
- Split the release notes into one page per release, grouped by minor version on
the overview page, with an "API changes" section per release generated from the
API pages' version histories (hooks/api_changes.py).
- Fact-check the release notes and version histories against the release tags and
correct wrong or misleading entries (e.g., json_serializer 2.1.0, merge_patch
3.1.0, items, count, operator[], to_bjdata, std::string_view key support).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
A code search of client code found many hand-written versions of
functionality the library already has: recursive object merges
(update(j, true) since 3.10.5), dotted-path getters (value() and
contains() with a JSON Pointer), get_or helpers (value() throws for a
member that is present but null), and adl_serializer specializations
for std::optional (supported since 3.12.0).
- modifying_values.md: describe both modes of update(), add a
defaults + user settings recipe, and stop recommending Merge Patch
for recursive merges.
- merge_patch.md: note that null deletes keys, so a merge patch is not
a general deep merge; link update().
- default_value.md: add "Nested values" (value/contains with a JSON
Pointer, building a pointer from a dotted path with operator/=) and
a warning that null and mistyped members are not missing.
- value.md: note that a null member is converted, not replaced by the
default.
- json_pointer.md: link value/contains/at with JSON Pointers.
- arbitrary_types.md: note that std::optional needs no serializer.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 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>
* 📝 Fix documentation gaps found in a full GitHub Discussions review
Reviewed all 1008 GitHub Discussions (2020-2026) for recurring questions
that better or more visible documentation would have avoided. Adds/expands
documentation for ~26 distinct gaps, including:
- New "Debugging" page collecting natvis, GDB pretty printer, LLDB status,
and JSON_DIAGNOSTICS pointers (previously scattered/undiscoverable)
- Thread-safety and schema-validation FAQ entries
- StringType's char-based requirement (no wstring/u16string/u32string)
- Brace-initialization-yields-arrays warning directly on the constructor
reference page (previously only in the FAQ, missed by users reading
the constructor docs)
- std::any exclusion from get<T>(), with a manual-dispatch example
- Non-string-keyed std::map serializing as an array of pairs
- ordered_json compatibility with NLOHMANN_DEFINE_TYPE_* macros
(already worked, was undocumented)
- std::array truncation on size-mismatched conversion (no exception)
- static_cast vs. get<std::optional<T>>() divergence
- Recipe for omitting a std::optional field instead of emitting null
- No built-in nesting-depth limit during parsing + a callback-based
workaround recipe
- Recipe for streaming a large homogeneous array via parser callbacks
- operator>> stream-position semantics for concatenated JSON values
- JSON Pointer array-vs-object creation rule for non-existing paths
- CMake target name (nlohmann_json_modules) needed to link C++20 modules
- ESP-IDF/PlatformIO: no official package, link to a community fork
- get(key, default) as the Python dict.get() equivalent
- reserve() recipe for pre-allocating array capacity
- JSONC as an alias for the existing ignore_comments/ignore_trailing_commas
combination (distinct from the unsupported JSON5)
- items() dereferenced-element type: decltype() idiom + detail-namespace
stability caveat
- Various macro/type-conversion limitations (MSGPACK_DEFINE_ARRAY
equivalent, char-array round-tripping, ADL serializer macro gap)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 🎨 fix format
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Niels Lohmann