Is there a simpler way of building and modifying a QJsonObject?

need4openid

For example, I would like to build the following json (its a simple one for the sake of the sample, in real life I have to construct much larger objects):

{
    "person":{
        "salary": {
            "min": 10000,
            "max": 20000
        }
    }
}

I build this object something like this (there might be syntax errors, I did not check):

QJsonObject({{"person", QJsonObject({{"salary", QJsonObject({{"min", 10000}, {"max", 20000}})}})}})

It can get quite ugly. Is there a better way of constructing such JsonOBject? The min/max values I obtain them dynamically at run time, so they cannot be imported with QJsonDocument::fromJson just like that.

jsulm

@need4openid Depending on your exact use case you can read JSON from a string.

SGaist

Hi,

Depending on what you would like to do you might also want to consider nlohmann's json library which is quite good.

mrjj

Hi
if you are using a c++ 11 compiler you can also use raw string literals.

 QString jsontemplate = R"(
    {
        "person":{
            "salary": {
                "min": %1,
                "max": %2
            }
        }
    })";

 QString finaleJson = jsontemplate.arg(1000).arg(2000);

 qDebug() << finaleJson;

ps. +5 for nlohmann's json. Its awesome.

Christian Ehrlicher

@need4openid said in Is there a simpler way of building and modifying a QJsonObject?:

QJsonObject({{"person", QJsonObject({{"salary", QJsonObject({{"min", 10000}, {"max", 20000}})}})}})

QJsonValue Foo::getValues() const
{
  return {{"person", m_person},
          {"salary", m_salary},
          {"min", m_min},
          {"max", m_max},
         }

MrShawn

I like to use the insert method.

    QJsonObject person;
    person.insert("min",10000);
    person.insert("max",20000);
    QJsonObject object;
    object.insert("person",person);

    QJsonDocument doc;
    doc.setObject(object);
    qDebug() << doc.toJson(QJsonDocument::Compact);

Trzmiel

If it is more convenient for you to manage the data in a collection (map or hash table), there are methods to create QJsonObject from QVariantMap and QVaraintHash.

int min = 10000, max = 20000;

QVariantMap salary;
salary["max"] = max;
salary["min"] = min;

QVariantMap person;
person["salary"] = salary;

QVariantMap jsonMap;
jsonMap["person"] = person;

QJsonDocument jsonDoc(QJsonObject::fromVariantMap(jsonMap));
qDebug() << jsonDoc.toJson(QJsonDocument::Compact);