Uso corretto di Poco C++ JSON per dati di analisi

Question

Qualcuno può indicarmi come funziona il Poco C++ JSON?

Precedentemente ho usato JsonReader e JsonToken. La libreria Poco C++ non sembra avere oggetti corrispondenti.

Come utilizzare, ad esempio, il parser JSON per creare un nome oggetto costituito dal valore JSON sul nome del tag?

Answer 1

MODIFICA: dalla 1.5.2, le cose sono state semplificate rendendo DefaultHandler, be ... predefinito (e rinominandolo con il suo nome proprio - ParseHandler. Quindi, se tutto ciò di cui si ha bisogno è l'analisi, non è necessario fornire esplicitamente il handler più:

// objects 
std::string json = "{ \"test\" : { \"property\" : \"value\" } }"; 
Parser parser; 
Var result = parser.parse(json); 
Object::Ptr object = result.extract<Object::Ptr>(); 
Var test = object->get("test"); 
object = test.extract<Object::Ptr>(); 
test = object->get("property"); 
std::string value = test.convert<std::string>(); 

// array of objects 
std::string json = "[ {\"test\" : 0}, { \"test1\" : [1, 2, 3], \"test2\" : 4 } ]"; 
Parser parser; 
Var result = parser.parse(json); 
Array::Ptr arr = result.extract<Array::Ptr>(); 
Object::Ptr object = arr->getObject(0);// 
assert (object->getValue<int>("test") == 0); 
object = arr->getObject(1); 
arr = object->getArray("test1"); 
result = arr->get(0); 
assert (result == 1); 

vedere this answer per maggiori dettagli

Answer 2

#include <iostream> 
#include <string> 
#include <Poco/JSON/JSON.h> 
#include <Poco/JSON/Parser.h> 
#include <Poco/Dynamic/Var.h> 

using namespace std; 
using namespace Poco::JSON; 

string GetValue(Object::Ptr aoJsonObject, const char *aszKey) { 
    Poco::Dynamic::Var loVariable; 
    string lsReturn; 
    string lsKey(aszKey); 

    // Get the member Variable 
    // 
    loVariable = aoJsonObject->get(lsKey); 

    // Get the Value from the Variable 
    // 
    lsReturn = loVariable.convert<std::string>(); 

    return lsReturn; 
} 

int main(int argc, char *argv[]) { 
    string lsJson; 
    Parser loParser; 

    lsJson = "{\"TransactionCode\":\"000000\",\"FileRecordSequenceNumber\":\"111111\",\"TcrSequenceNumber\":\"222222\",\"TransactionRouteIndicator\":\"ABCDE\",\"MerchantEstablishmentNumber\":\"00000000000\",\"MerchantName\":\"BBBBBBBBB\",\"MerchantCity\":\"CCCCCCCC\"}"; 

    cout << lsJson << endl; 

    // Parse the JSON and get the Results 
    // 
    Poco::Dynamic::Var loParsedJson = loParser.parse(lsJson); 
    Poco::Dynamic::Var loParsedJsonResult = loParser.result(); 

    // Get the JSON Object 
    // 
    Object::Ptr loJsonObject = loParsedJsonResult.extract<Object::Ptr>(); 

    // Get the values for the member variables 
    // 
    // 
    cout << "TransactionCode    " << GetValue(loJsonObject, "TransactionCode")    << endl; 
    cout << "FileRecordSequenceNumber " << GetValue(loJsonObject, "FileRecordSequenceNumber")  << endl; 
    cout << "TcrSequenceNumber   " << GetValue(loJsonObject, "TcrSequenceNumber")    << endl; 
    cout << "TransactionRouteIndicator " << GetValue(loJsonObject, "TransactionRouteIndicator")  << endl; 
    cout << "MerchantEstablishmentNumber " << GetValue(loJsonObject, "MerchantEstablishmentNumber") << endl; 
    cout << "MerchantName    " << GetValue(loJsonObject, "MerchantName")     << endl; 
    cout << "MerchantCity    " << GetValue(loJsonObject, "MerchantCity")     << endl; 

    return 0; 

} 

Results: 
{"TransactionCode":"000000","FileRecordSequenceNumber":"111111","TcrSequenceNumber":"222222","TransactionRouteIndicator":"ABCDE","MerchantEstablishmentNumber":"00000000000","MerchantName":"BBBBBBBBB","MerchantCity":"CCCCCCCC"} 
TransactionCode    000000 
FileRecordSequenceNumber 111111 
TcrSequenceNumber   222222 
TransactionRouteIndicator ABCDE 
MerchantEstablishmentNumber 00000000000 
MerchantName    BBBBBBBBB 
MerchantCity    CCCCCCCC