push_back() [3/4]

template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer, class BinaryType = std::vector<std::uint8_t>>

void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::push_back ( const typename object_t::value_type &  val )

inline

add an object to an object

Inserts the given element val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting val.

Parameters

[in]

val

the value to add to the JSON object

Exceptions

type_error.308

when called on a type other than JSON object or null; example: "cannot use push_back() with number"

@complexity Logarithmic in the size of the container, O(log(size())).

@liveexample{The example shows how push_back() and += can be used to add elements to a JSON object. Note how the null value was silently converted to a JSON object.,push_back__object_t__value}

Since

version 1.0.0

Definition at line 23237 of file json.hpp.

    {
        // push_back only works for null objects or objects
        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object())))
        {
            JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()), *this));
        }
 
        // transform null object into an object
        if (is_null())
        {
            m_type = value_t::object;
            m_value = value_t::object;
            assert_invariant();
        }
 
        // add element to object
        auto res = m_value.object->insert(val);
        set_parent(res.first->second);
    }