diff options
| -rw-r--r-- | src/corelib/serialization/qjsoncbor.cpp | 21 | ||||
| -rw-r--r-- | src/corelib/serialization/qjsonvalue.cpp | 34 |
2 files changed, 43 insertions, 12 deletions
diff --git a/src/corelib/serialization/qjsoncbor.cpp b/src/corelib/serialization/qjsoncbor.cpp index 8bb04fa3bf..e0eab74a02 100644 --- a/src/corelib/serialization/qjsoncbor.cpp +++ b/src/corelib/serialization/qjsoncbor.cpp @@ -679,17 +679,22 @@ static void appendVariant(QCborContainerPrivate *d, const QVariant &variant) \row \li \l QUuid \li Uuid \endtable - For any other types, this function will return Null if the QVariant itself - is null, and otherwise will try to convert to string using - QVariant::toString(). If the conversion to string fails, this function - returns Undefined. + If QVariant::isNull() returns true, a null QCborValue is returned or + inserted into the list or object, regardless of the type carried by + QVariant. Note the behavior change in Qt 6.0 affecting QVariant::isNull() + also affects this function. + + For other types not listed above, a conversion to string will be attempted, + usually but not always by calling QVariant::toString(). If the conversion + fails the value is replaced by an Undefined CBOR value. Note that + QVariant::toString() is also lossy for the majority of types. Please note that the conversions via QVariant::toString() are subject to - change at any time. QCborValue may be extended in the future to support - more types, which will result in a change in how this function performs - conversions. + change at any time. Both QVariant and QCborValue may be extended in the + future to support more types, which will result in a change in how this + function performs conversions. - \sa toVariant(), fromJsonValue(), QCborArray::toVariantList(), QCborMap::toVariantMap() + \sa toVariant(), fromJsonValue(), QCborArray::toVariantList(), QCborMap::toVariantMap(), QJsonValue::fromVariant() */ QCborValue QCborValue::fromVariant(const QVariant &variant) { diff --git a/src/corelib/serialization/qjsonvalue.cpp b/src/corelib/serialization/qjsonvalue.cpp index 5eb33bd2a3..34fa84cdc1 100644 --- a/src/corelib/serialization/qjsonvalue.cpp +++ b/src/corelib/serialization/qjsonvalue.cpp @@ -439,10 +439,36 @@ void QJsonValue::swap(QJsonValue &other) noexcept "stringification" of map keys. \endtable - For all other QVariant types a conversion to a QString will be attempted. If the returned string - is empty, a Null QJsonValue will be stored, otherwise a String value using the returned QString. - - \sa toVariant() + \section2 Loss of information and other types + + QVariant can carry more information than is representable in JSON. If the + QVariant is not one of the types above, the conversion is not guaranteed + and is subject to change in future versions of Qt, as the UUID one did. + Code should strive not to use any other types than those listed above. + + If QVariant::isNull() returns true, a null QJsonValue is returned or + inserted into the list or object, regardless of the type carried by + QVariant. Note the behavior change in Qt 6.0 affecting QVariant::isNull() + also affects this function. + + A floating point value that is either an infinity or NaN will be converted + to a null JSON value. Since Qt 6.0, QJsonValue can store the full precision + of any 64-bit signed integer without loss, but in previous versions values + outside the range of ±2^53 may lose precision. Unsigned 64-bit values + greater than or equal to 2^63 will either lose precision or alias to + negative values, so QMetaType::ULongLong should be avoided. + + For other types not listed above, a conversion to string will be attempted, + usually but not always by calling QVariant::toString(). If the conversion + fails the value is replaced by a null JSON value. Note that + QVariant::toString() is also lossy for the majority of types. + + Please note that the conversions via QVariant::toString() are subject to + change at any time. Both QVariant and QJsonValue may be extended in the + future to support more types, which will result in a change in how this + function performs conversions. + + \sa toVariant(), QCborValue::fromVariant() */ QJsonValue QJsonValue::fromVariant(const QVariant &variant) { |