// (1) template<typename ValueType> ValueType get() const noexcept( noexcept(JSONSerializer<ValueType>::from_json( std::declval<const basic_json_t&>(), std::declval<ValueType&>()))); // (2) template<typename BasicJsonType> BasicJsonType get() const; // (3) template<typename PointerType> PointerType get_ptr(); template<typename PointerType> constexpr const PointerType get_ptr() const noexcept;
Explicit type conversion between the JSON value and a compatible value which is CopyConstructible and DefaultConstructible. The value is converted by calling the json_serializer<ValueType>
from_json()
method.
The function is equivalent to executing
ValueType ret; JSONSerializer<ValueType>::from_json(*this, ret); return ret;
This overloads is chosen if:
ValueType
is not basic_json
,json_serializer<ValueType>
has a from_json()
method of the form void from_json(const basic_json&, ValueType&)
, andjson_serializer<ValueType>
does not have a from_json()
method of the form ValueType from_json(const basic_json&)
If the type is not CopyConstructible and not DefaultConstructible, the value is converted by calling the json_serializer<ValueType>
from_json()
method.
The function is then equivalent to executing
return JSONSerializer<ValueTypeCV>::from_json(*this);
This overloads is chosen if:
ValueType
is not basic_json
andjson_serializer<ValueType>
has a from_json()
method of the form ValueType from_json(const basic_json&)
If json_serializer<ValueType>
has both overloads of from_json()
, the latter one is chosen.
Overload for basic_json
specializations. The function is equivalent to executing
return *this;
Explicit pointer access to the internally stored JSON value. No copies are made.
ValueType
: the value type to return
BasicJsonType
: a specialization of basic_json
PointerType
: pointer type; must be a pointer to array_t
, object_t
, string_t
, boolean_t
, number_integer_t
, or number_unsigned_t
, number_float_t
, or binary_t
. Other types will not compile.
ValueType
#!cpp *this
, converted into BasicJsonType
#!cpp nullptr
otherwiseDepends on what json_serializer<ValueType>
from_json()
method throws
!!! warning
Writing data to the pointee (overload 3) of the result yields an undefined state.
??? example
The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers, (2) A JSON array can be converted to a standard `std::vector<short>`, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map<std::string, json>`. ```cpp --8<-- "examples/get__ValueType_const.cpp" ``` Output: ```json --8<-- "examples/get__ValueType_const.output" ```
??? example
The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `#cpp nullptr` is returned if the value and the requested pointer type does not match. ```cpp --8<-- "examples/get__PointerType.cpp" ``` Output: ```json --8<-- "examples/get__PointerType.output" ```
basic_json
in version 3.2.0.