So, I am learning my way around Q_PROPERTY, QMetaObject and QMetaProperty.
I have built a working GUI, but whenever I run the script, I get an error
Can anyone tell me what I did wrong/am doing wrong? The QDout() function, as mentioned, is only there to display something if I successfully connected the 'Print' Button with the QDout() function.
Below I have my files that associate with the Qt Project I am working on. This is nothing serious, only for me to learn how to do it.
qt.core.qobject.connect: QObject::connect: No such slot FileInput::writeToFile()
My Header Files:
fileinput.h
#ifndef FILEINPUT_H
#define FILEINPUT_H
#include <QWidget>
#include <QPushButton>
#include "person.h"
class FileInput : public QWidget
{
Q_OBJECT
public:
FileInput(QWidget *parent = nullptr);
void set_GUI();
public slots:
void writeToFile(QObject *obj);
void QDout(); //just a test function to test my 'connect' part
private:
QPushButton *xx;
QPushButton *pp;
};
#endif // FILEINPUT_H
person.h
#ifndef PERSON_H
#define PERSON_H
#include <QObject>
#include <QDate>
class Person : public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ getName WRITE setName)
Q_PROPERTY(QDate birth READ getBirth WRITE setBirth)
public:
Person();
Person(QString n, QDate d);
QString getName() const;
QDate getBirth() const;
void setName(QString n);
void setBirth(QDate d);
private:
QString name;
QDate birthDate;
};
class Product : public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ getName WRITE setName)
Q_PROPERTY(double price READ getPrice WRITE setPrice)
public:
Product();
Product(QString n, double d);
QString getName() const;
double getPrice() const;
void setName(QString n);
void setPrice(double d);
private:
QString name;
double price;
};
#endif // PERSON_H
And then i have 3 .cpp
files
filminput.cpp
#include "fileinput.h"
#include <QPushButton>
#include <QVBoxLayout>
#include <QMetaObject>
#include <QMetaProperty>
#include <QFile>
#include <QTextStream>
FileInput::FileInput(QWidget *parent)
: QWidget(parent)
{
}
void FileInput::set_GUI()
{
QWidget *w = new QWidget;
w->resize(250,250);
w->setWindowTitle("Q Meta Nonsence");
Product lem = Product();
lem.setName("PHIL");
lem.setPrice(16.45);
xx = new QPushButton("Exit");
pp = new QPushButton("Print");
QVBoxLayout *ll = new QVBoxLayout;
ll->addWidget(xx);
ll->addWidget(pp);
ll->setSpacing(25);
w->setLayout(ll);
w->show();
connect(xx,SIGNAL(clicked()),w,SLOT(close()));
connect(pp,SIGNAL(clicked()),this,SLOT(writeToFile(lem)));
}
void FileInput::QDout() //just prints 'success' when pressing the 'print' button
{
qDebug() << "success";
}
//this next function is supposed to write to the data.txt file
void FileInput::writeToFile(QObject *obj)
{
QFile file("C:/Users/marti/Documents/Qt/QM/data.txt");
if(!file.open(QFile::WriteOnly|QFile::Text|QFile::Append))
{
qDebug() << "Already open or there is another issue";
file.close();
}
QTextStream toFile(&file);
const QMetaObject *mo = obj->metaObject();
for(int i=mo->propertyOffset(); i<mo->propertyCount(); i )
{
const QMetaProperty prop = mo->property(i);
QString name = prop.name();
QVariant value = prop.read(obj);
QString valStr = value.toString();
toFile << name << ": " << valStr << "\n";
}
file.close();
}
person.cpp
#include "person.h"
Person::Person()
{
name = QString();
birthDate = QDate();
}
Person::Person(QString n, QDate d)
{
name = n;
birthDate = d;
}
QString Person::getName() const
{
return name;
}
QDate Person::getBirth() const
{
return birthDate;
}
void Person::setName(QString n)
{
name = n;
}
void Person::setBirth(QDate d)
{
birthDate = d;
}
Product::Product()
{
name = QString();
price = 0.0;
}
Product::Product(QString n, double d)
{
name = n;
price = d;
}
QString Product::getName() const
{
return name;
}
double Product::getPrice() const
{
return price;
}
void Product::setName(QString n)
{
name = n;
}
void Product::setPrice(double d)
{
price = d;
}
main.cpp
#include "fileinput.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
FileInput w;
w.set_GUI();
return a.exec();
}
CodePudding user response:
You're using the older connect syntax which masks the problem that you're connecting a signal with no parameters to a slot that wants a parameter. To fix it use the new syntax and use a lambda to provide the extra parameter.
connect(pp, &QPushButton::clicked, this, [=](){ writeToFile(lem); });