我正在尝试在c ++中解析以下JSON文件。我想遍历'attributes'数组并获取该属性对象的string：'name'的特定值的string：'value'的值。例如：我想解析此JSON文件并获取“质量”的“值”。
{
"active": true,
"apiTier": 0,
"attributes": [
{
"description": "Given in the datasheet as '0.33 kg (0.73 lbm)'.",
"maximumValue": "",
"measurementUnit": "kg",
"minimumValue": "",
"name": "mass",
"productConfiguration": "base",
"value": "0.33"
},
{
"description": "",
"maximumValue": "",
"measurementUnit": "",
"minimumValue": "",
"name": "propellant-type",
"productConfiguration": "base",
"value": "hydrazine"
},
{
"description": "Given in the datasheet as 'Thrust/Steady State' and the specified value is also reported as '(0.05-0.230) lbf'.",
"maximumValue": "1.02",
"measurementUnit": "N",
"minimumValue": "0.22",
"name": "thrust",
"productConfiguration": "base",
"value": ""
}
]
我正在尝试使用RapidJSON库在C ++中解析JSON文件。以下是我解析JSON文件的实现。我想在for循环中进行操作，对于字符串“名称”（例如：mass）的特定“值”，获取字符串的其他“值”，例如“ maximumValue”，“ minimumValue”，“ value” '等
#include <fstream>
#include <sstream>
#include <string>
#include <rapidjson/document.h>
int main()
{
std::ifstream inputFile( "/path/to/json/file/" );
std::stringstream jsonDocumentBuffer;
std::string inputLine;
while ( std::getline( inputFile, inputLine ) )
{
jsonDocumentBuffer << inputLine << "\n";
}
rapidjson::Document config;
config.Parse( jsonDocumentBuffer.str( ).c_str( ) );
assert(config.IsObject());
const rapidjson::Value& attributes = config["attributes"];
assert(attributes.IsArray());
int counter = 0;
for (rapidjson::Value::ConstValueIterator itr = attributes.Begin(); itr != attributes.End(); ++itr)
{
const rapidjson::Value& attribute = *itr;
assert(attribute.IsObject()); // each attribute is an object
for (rapidjson::Value::ConstMemberIterator itr2 = attribute.MemberBegin(); itr2 != attribute.MemberEnd(); ++itr2)
{
std::cout << itr2->name.GetString() << " : " << itr2->value.GetString() << std::endl;
}
}
编辑1：我找到了一种关于如何遍历属性数组并访问属性数组中每个对象的每个字符串及其值的解决方案。但是，我想做的是获取字符串“名称”的特定值（例如质量）的任何字符串（例如：“ maximumValue”，“ minimumValue”，“ Value”）等值。
如果只想获取选定属性的指定属性，则可以使用以下函数：
#include <iostream>
#include <vector>
#include <map>
#include "rapidjson/document.h"
std::map<std::string, std::string> mapForAttributeThatMatchesName(const rapidjson::Value& attributes, const std::string& findMemberName, const std::string& findMemberValue, const std::vector<std::string>& keysToRetrieve) {
std::map<std::string, std::string> result;
for (rapidjson::Value::ConstValueIterator itr = attributes.Begin(); itr != attributes.End(); ++itr) {
const rapidjson::Value::ConstMemberIterator currentAttribute = itr->FindMember(findMemberName.c_str());
if (currentAttribute != itr->MemberEnd() && currentAttribute->value.IsString()) {
if (currentAttribute->value == findMemberValue.c_str()) {
for (auto &keyToRetrieve : keysToRetrieve) {
const rapidjson::Value::ConstMemberIterator currentAttributeToReturn = itr->FindMember(keyToRetrieve.c_str());
if (currentAttributeToReturn != itr->MemberEnd() && currentAttributeToReturn->value.IsString()) {
result[keyToRetrieve] = currentAttributeToReturn->value.GetString();
}
}
return result;
}
}
}
return result;
}
您可以像这样测试它：
const rapidjson::Value& attributes = config["attributes"];
assert(attributes.IsArray());
std::vector<std::string> keysToRetrieve = {"maximumValue", "minimumValue"};
std::map<std::string, std::string> mapForResult = mapForAttributeThatMatchesName(attributes, "name", "mass", keysToRetrieve);
for (auto &mapItem : mapForResult) {
std::cout << mapItem.first << ":" << mapItem.second << "\n";
}
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