Some days ago I introduced the possibility to serialize a QObject instance to JSON. Today I’m going to show you the opposite operation: initializing a QObject using a JSON object.
I refactored a bit my latest changes: I created a new class called QObjectHelper that provides the methods required to convert a QObject instance to a QVariantMap and vice-versa.
This class can be used in conjunction with the Serializer and Parser classes to serialize and deserialize QObject instances to and from JSON.
Let me show a quick example, suppose the declaration of Person class looks like this:
class Person : public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName)
Q_PROPERTY(int phoneNumber READ phoneNumber WRITE setPhoneNumber)
Q_PROPERTY(Gender gender READ gender WRITE setGender)
Q_PROPERTY(QDate dob READ dob WRITE setDob)
Q_ENUMS(Gender)
public:
Person(QObject* parent = 0);
~Person();
QString name() const;
void setName(const QString& name);
int phoneNumber() const;
void setPhoneNumber(const int phoneNumber);
enum Gender {Male, Female};
void setGender(Gender gender);
Gender gender() const;
QDate dob() const;
void setDob(const QDate& dob);
private:
QString m_name;
int m_phoneNumber;
Gender m_gender;
QDate m_dob;
};
From QObject to JSON
The following code will serialize an instance of Person to JSON :
Person person;
person.setName("Flavio");
person.setPhoneNumber(123456);
person.setGender(Person::Male);
person.setDob(QDate(1982, 7, 12));
QVariantMap variant = QObjectHelper::qobject2qvariant(&person);
Serializer serializer;
qDebug() << serializer.serialize( variant);
The generated output will be:
{ "dob" : "1982-07-12", "gender" : 0, "name" : "Flavio", "phoneNumber" : 123456 }
From JSON to QObject
Suppose you have the following JSON data stored into a QString:
{ "dob" : "1982-07-12", "gender" : 0, "name" : "Flavio", "phoneNumber" : 123456 }
The following code will initialize an already allocated instance of Person using the JSON values:
Parser parser;
QVariant variant = parser.parse(json);
Person person;
QObjectHelper::qvariant2qobject(variant.toMap(), &person);
A new release
These changes have been included inside the new release of QJson: 0.7.0.
Packages for openSUSE are building right now.
Tags:
KDE,
qjson,
Qt
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