如何通过pushButton点击Qt为json数据创建两个消息事件？

Question

我该如何发消息？

我想要制作2个消息事件。首先，如果我的lineEdits中没有包含任何内容并按下按钮。必须出现错误消息“您还没有包含数据”。第二，如果我包括我的lineEdits并按下按钮。必须来的消息“你已经包含了数据。”但它对我不起作用。如果我按下按钮，程序保存空json。如果我在lineEdits中按下写入数据并按下按钮，则程序保存为普通的json。但无论我怎么写，程序总是会覆盖旧的json文件。我总是得到我存储数据的日志记录。

这是我的代码：

我的.Cpp文件：

#include "address_dialog.h"
#include "ui_address_dialog.h"

Address_Dialog::Address_Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Address_Dialog)
{
    ui->setupUi(this);

    connect(ui->pb_Cancel,SIGNAL(clicked(bool)),this,SLOT(close()));
    //Save data in json on click
    connect(ui->pb_save,SIGNAL(clicked(bool)),
    this,SLOT(on_pb_save_clicked()));
}
Address_Dialog::~Address_Dialog()
{
    delete ui;
}  

void Address_Dialog::SaveDat()
{
    m_address.mVorname= ui->le_Vorname->text();
    m_address.mNachname= ui->le_Nachname->text();
    m_address.mLand= ui->le_Land->text();
    m_address.mName= ui->le_Name->text();
    m_address.mPassword= ui->le_Password->text();

    QJsonObject json_obj;

    json_obj["FirstName"]= m_address.mVorname;
    json_obj["MiddleName"]= m_address.mNachname;
    json_obj["Country"]= m_address.mLand;
    json_obj["NickName"]= m_address.mName;
    json_obj["Password"]= m_address.mPassword;

    //Open the file for Recording using the path specified
    QString file_path = "C:/Users/frs/Documents/test_obj.json";

    QFile save_file(file_path);
    save_file.open(QIODevice::WriteOnly);
    //if(!save_file.open(QIODevice::WriteOnly))
        //QMessageBox::warning(0,"Error","Cannot open the file");

    QJsonDocument json_doc(json_obj);
    QString json_string = json_doc.toJson();

    if(save_file.write(json_string.toLocal8Bit()))
       QMessageBox::information(0,"Saving....",
            "The item has been successfully added");
    else
       QMessageBox::critical(0,"Error","The item cannot be added");
       save_file.close();
}

void Address_Dialog::on_pb_save_clicked()
{
    SaveDat();
}

那是我的.H文件

#ifndef ADDRESS_DIALOG_H
#define ADDRESS_DIALOG_H

#include <QDialog>
#include <QMessageBox>
#include "address.h"
#include <QFile>
#include <QJsonObject>
#include <QJsonArray>
#include <QJsonDocument>
#include <QString>
#include <QDir>

namespace Ui
{
    class Address_Dialog;
}

class Address_Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Address_Dialog(QWidget *parent = 0);
    ~Address_Dialog();

    Address m_address;//Creation of the Class object <=> /*QString mVorname, 
      // mNachname, mLand, mName, mPassword;*/

private slots:
    void on_pb_save_clicked();
    void SaveDat();

private:
    Ui::Address_Dialog *ui;

};

#endif // ADDRESS_DIALOG_H

Answer 1

我找到了解决方案。那很简单。我感谢大家的回应。

这是我的代码：

if(ui->le_Vorname->text().isEmpty() || ui->le_Nachname->text().isEmpty() || 
        ui->le_Land->text().isEmpty() || ui->le_Name->text().isEmpty() || 
        ui->le_Password->text().isEmpty())
{
        ui->pb_save->setEnabled(false);
        QMessageBox::critical(0,"Error","The item cannot be added");
}else
{
        ui->pb_save->setEnabled(true);
        save_file.write(json_string.toLocal8Bit());
        QMessageBox::information(0,"Saving....", "The item has been successfully added");
}
   save_file.close();