Usage example of qjsonobject

Introduce ： Responsible for packaging JSON object , yes key / It's worth it list , among Key is unique String , Values are determined by QJsonValue Express .

1——QJsonObjec： Encapsulates the Json The object in

Interface and QMap be similar , All have size()、insert() and remove() Wait for the operation , You can also use standards C++ The iterator pattern iterates over its contents .

Examples of use ：

As shown in the figure below ： If we want to write this data , How to write it in ？

 

QJsonObject gObj = JSONDATA.getSpecifyGroup(m_iSelectBtnIndex);
// Here read the first QJsonObject object , You can see it yourself according to your needs 

// Next, we will read it layer by layer 

// New addition effect
QJsonArray chValueArray;// This is an arbitrary array to be added , It's useful to 
for(int i = 0 ; i <  ui->cbLightChanleNum->currentText().toInt() ; i++)
{
    chValueArray.append(QJsonValue(0));
}
QJsonObject eObj  =  gObj[JSONKEY::EFFECT_JSONKEY].toObject() ;
QJsonArray pArry = eObj[JSONKEY::PROGRAM_JSONKEY].toArray();
for(int i=0; i<pArry.size();i++)
{
     QJsonObject eObject = pArry.at(i).toObject();
     for(int i = 0; i < addrArray.size(); i++)
         {
                                        eObject.insert(QString::number(addrArray.at(i).toInt()),QJsonValue(chValueArray));
         }
         pArry.replace(i,eObject);
}
eObj[JSONKEY::PROGRAM_JSONKEY] = pArry;
gObj[JSONKEY::EFFECT_JSONKEY] = eObj;
JSONDATA.setSpecifyGroup(m_iSelectBtnIndex,gObj);// Here is the encapsulated deposit Json File interface 

Just remember a little ,[] The one in front is Json Array Format ,{} That's it. Json Object format

2——QJsonArray：  Encapsulates the Json Array in

3——QJsonDocument： converter
Known above JSON There are two formats , namely JSON Array and JSON object , They will eventually take advantage of JSON Complete serialization , Convert the data to the corresponding string , Or there is another case where a string is converted to JSON Array and JSON object .

ordinary JSON object

{
    "Cross Platform": true,
    "From": 1991,
    "Name": "Qt"
}

  Generate ：

//  structure  JSON  object 
QJsonObject json;
json.insert("Name", "Qt");
json.insert("From", 1991);
json.insert("Cross Platform", true);

//  structure  JSON  file 
QJsonDocument document;
document.setObject(json);
QByteArray byteArray = document.toJson(QJsonDocument::Compact);
QString strJson(byteArray);

qDebug() << strJson;

ordinary JSON analysis

QJsonParseError jsonError;
//  Turn into  JSON  file 
QJsonDocument doucment = QJsonDocument::fromJson(byteArray, &jsonError); 
//  No error occurred in parsing 
if (!doucment.isNull() && (jsonError.error == QJsonParseError::NoError)) 
{  
    if (doucment.isObject()) 
    { 
        // JSON  Document as object 
        QJsonObject object = doucment.object();  //  Convert to object 
        if (object.contains("Name")) 
        {  //  Contains the specified  key
            QJsonValue value = object.value("Name");  //  Get specified  key  Corresponding  value
            if (value.isString()) 
            {  //  Judge  value  Is it a string 
                QString strName = value.toString();  //  take  value  Convert to string 
                qDebug() << "Name : " << strName;
            }
        }
        if (object.contains("From")) 
        {
            QJsonValue value = object.value("From");
            if (value.isDouble()) 
            {
                int nFrom = value.toVariant().toInt();
                qDebug() << "From : " << nFrom;
            }
        }
        if (object.contains("Cross Platform")) 
        {
            QJsonValue value = object.value("Cross Platform");
            if (value.isBool()) 
            {
                bool bCrossPlatform = value.toBool();
                qDebug() << "CrossPlatform : " << bCrossPlatform;
            }
        }
    }
}

 

 4——QJsonValue：  It is the packaging of the data type previously transferred ,C++ There are different declarations for different data types in ,QJsonValue Class is using constructors All kinds of data types are unified , Packed in one type , It's easier to operate .

QJsonValue Can be encapsulated There are six basic data types ：

Boolean type	QJsonValue::Bool
Floating point type （ Including plastic surgery ）	QJsonValue::Double
String type	QJsonValue::String
Json An array type	QJsonValue::Array
Json object type	QJsonValue::Object
Null type	QJsonValue::Null

（1） Various types can be accessed through QJsonValue The constructor of is encapsulated as a class object ;

（2） If we get one QJsonValue object , How to determine what type of data is encapsulated inside ？

//  Whether it is Json Array 
bool isArray() const;
//  Whether it is Json object 
bool isObject() const;
//  Whether it is Boolean 
bool isBool() const;
//  Whether it is a floating point type ( Shaping is also judged by this function )
bool isDouble() const;
//  Whether it is a null value type 
bool isNull() const;
//  Is it a string type 
bool isString() const;
//  Whether it is an undefined type ( Unrecognized type )
bool isUndefined() const;

（3） After getting the actual type of the internal data of the object through the judgment function , If necessary, it can be converted to the corresponding basic data type again .

//  Convert to Json Array 
QJsonArray toArray(const QJsonArray &defaultValue) const;
QJsonArray toArray() const;
//  Convert to boolean type 
bool toBool(bool defaultValue = false) const;
//  Convert to floating point type 
double toDouble(double defaultValue = 0) const;
//  Convert to plastic 
int toInt(int defaultValue = 0) const;
//  Convert to Json object 
QJsonObject toObject(const QJsonObject &defaultValue) const;
QJsonObject toObject() const;
//  Convert to string type 
QString toString() const;
QString toString(const QString &defaultValue) const;

• QJsonValue And QVariant Interturn

QJsonValue fromVariant(const QVariant &variant)
QVariant QJsonValue::toVariant() const

• QJsonValue It can be done with QJsonObject,QJsonArray Interturn

QJsonValue::QJsonValue(const QJsonArray &a)
QJsonObject QJsonValue::toObject() const
QJsonValue::QJsonValue(const QJsonObject &o)
QJsonArray QJsonValue::toArray() const