Matty's questions

你好。我正在编写一个用于处理笔记的小程序。现在已经实现了最低限度的功能：可以创建、编辑和删除注释。对于 GUI，我有 Qt，基础是 SQLite。一般来说，一切正常，做我想做的事。但是我的编程经验趋于零，所以我怀疑有很多缺点我无法修复，因为我不知道去哪里找。我希望您指出所有明显的错误/问题/缺点。对从划分到类的逻辑到可能的内存泄漏的一切都感兴趣。

现在基本上有 12 个类：

• 4 个窗口：MattyNotesMainWindow, MattySettingsDialog, addNoteDialog,MattyMessageBox
• 使用数据库的类DbManager
• 用于编写 SQL 查询的类QueryConstructor
• 注解类本身MattyNote
• 用于可视化显示注释的构造函数类MattyGroupBox
• 排序和显示笔记的类NoteHolder
• css控制类MattyStyleSheetEditor
• 用于存储字符串和字符的类Constants
• 手表MattyClocks

我知道不太可能有人会校对所有代码，因此也许您可以查看类及其方法并说出哪些是多余的，或者查看任何一个类并指出其中的缺陷。

例如连接数据库、编辑已有笔记、从数据库中删除所有笔记等功能：

bool DbManager::connect(const QString & path)
{
    MattyNotesDb = QSqlDatabase::addDatabase("QSQLITE");
    MattyNotesDb.setDatabaseName(path);

    if(QFile::exists(path))
    {
        if (!MattyNotesDb.open())
        {
            showIsNotOpenedError();
            MattyNotesDb.close();

            return false;
        }
        else
        {
            PathToDb = MattyNotesDb.databaseName();
        }

        return true;
    }
    else
    {
        return false;
    }
}

bool DbManager::editNote(MattyNote & Note, int NoteId)
{
    if (connected())
    {
        QueryConstructor Edit;
        Edit.setTableName(QStringLiteral("Notes"));

        Edit.addWhereFieldValue(QStringLiteral("NoteId"), QString::number(NoteId));

        QMap<QString, QString> NoteTemp;
        NoteTemp["NoteTitle"] = "\'" + Note.getTitle() + "\'";
        NoteTemp["NoteType"] = "\'" + Note.getType() + "\'";
        NoteTemp["NoteText"] = "\'" + Note.getText() + "\'";
        NoteTemp["EventTime"] = "\'" + Note.getEventTime() + "\'";
        NoteTemp["EventDate"] = "\'" + Note.getEventDate() + "\'";
        NoteTemp["CrTime"] = "\'" + Note.getCrTime() + "\'";
        NoteTemp["CrDate"] = "\'" + Note.getCrDate() + "\'";
        NoteTemp["TypeId"] = QString::number(Note.getTypeId());

        Edit.setWhatToSetFieldValue(NoteTemp); //

        QSqlQuery editNoteQuery;
        return editNoteQuery.exec(Edit.constructUpdateQuery());
    }
    else
    {
        return false;
    }
}

QVector<MattyNoteRow> DbManager::showNotes()
{
    if (connected())
    {
        QVector<MattyNoteRow> VectorOfNoteRows;

        QueryConstructor SelectAllNotes;
        SelectAllNotes.setTableName(QStringLiteral("Notes"));
        SelectAllNotes.setOrderByClause("NoteId", Descending);

        QSqlQuery getAllNotesQuery(MattyNotesDb);

        if( getAllNotesQuery.exec(SelectAllNotes.constructSelectQuery()))
        {
            while (getAllNotesQuery.next())
            {
                MattyNoteRow Row;

                Row.NoteId=getAllNotesQuery.value("NoteId").toInt();
                Row.NoteTitle=getAllNotesQuery.value("NoteTitle").toString();
                Row.NoteType=getAllNotesQuery.value("NoteType").toString();
                Row.NoteText=getAllNotesQuery.value("NoteText").toString();
                Row.EventTime=getAllNotesQuery.value("EventTime").toString();
                Row.EventDate=getAllNotesQuery.value("EventDate").toString();
                Row.CrTime=getAllNotesQuery.value("CrTime").toString();
                Row.CrDate=getAllNotesQuery.value("CrDate").toString();
                Row.TypeId=getAllNotesQuery.value("TypeId").toInt();

                VectorOfNoteRows.push_back(Row);
            }
        }
        else
        {
            QMessageBox::critical(NULL, QObject::tr("Error"), getAllNotesQuery.lastError().text());
        }

        return VectorOfNoteRows;
    }
    else
    {
        return QVector<MattyNoteRow>();
    }
}

将注释发送到表单：

    void NoteHolder::publishNotes(QWidget* ParentWidget)
    {
        erasePublishedNotes(ParentWidget);

        getAllNotes();

        QVector<class MattyNote>::iterator NoteNumber;
        int i;
        for (NoteNumber = ListOfAllNotes.begin(), i=0; NoteNumber < ListOfAllNotes.end();NoteNumber++, i++)
        {

            MattyGroupBox* MyGroupBox = new MattyGroupBox(*NoteNumber, ParentWidget);

            ParentWidget->layout()->addWidget(MyGroupBox);
        }
    }

void NoteHolder::erasePublishedNotes(QWidget* ParentWidget)
{
    MattyGroupBox* MgbTemp;
    while ((MgbTemp = ParentWidget->findChild<MattyGroupBox*>()) != 0)
    {
        delete MgbTemp;
    }

    QGroupBox* GbTemp;
    while ((GbTemp = ParentWidget->findChild<QGroupBox*>()) != 0)
    {
        delete GbTemp;
    }
}

void NoteHolder::getAllNotes()
{
    TotalNoteCount = 0;

    if (!ListOfAllNotes.isEmpty())
        ListOfAllNotes.clear();

    QVector<struct MattyNoteRow> ListOfRows = DbManager::showNotes();

    for (int i = 0; i < ListOfRows.length();i++)
    {
        MattyNote TempNote(ListOfRows[i]);
        ListOfAllNotes.append(TempNote);
        TotalNoteCount++;
    }
}

整个源代码可以在这里看到：GitHub

分离成类、它们的方法、调用、依赖关系等。这里：doxygen

现在我的数据库调用如下所示：

   QVector<QStringList> VectorOfRecords;

        QueryConstructor SelectAll;
        SelectAll.setTableName(QStringLiteral("TableName"));
        SelectAll.setOrderByClause("Id", Descending);

        QSqlQuery getRecordsQuery(Database);

        if( getRecordsQuery.exec(SelectAll.constructSelectQuery()))
        {
            while (getRecordsQuery.next())
            {
                QStringList Row;
                for (int i = 0;i < 9;i++)
                {
                    Row.push_back(getRecordsQuery.value(i).toString());
                }
                VectorOfRecords.push_back(Row);
            }
        }
        else
        {
            QMessageBox::critical(NULL, QObject::tr("Error"), getRecordsQuery.lastError().text());
        }

QueryConstructor 是我的类，在此示例中，它请求显示整个表。

我想更换这个

getRecordsQuery.value(i)

不是通过索引，而是通过名称来寻址。因为在我看来，使用数字在某种程度上是不可靠和不可读的。我怎样才能做到这一点？所以一切正常，但我想制作一个更灵活的系统。

我有一个项目要从 Visual Studio 迁移到 QtCreator。编译器相应地改变。现在是使用数据库的问题。所有这些都在工作室工作，但我不明白 QtCreator 和 MinGW 不喜欢什么。具体来说，问题归结为在处理 SQL 查询时，它没有看到表。如果您查看 SQLiteManager，那么所有表都已就位，并且执行查询并提供所需的输出。

问题在这里：

QVector<QStringList> DbManager::showNotes()
{
    if (MattyNotesDb.isOpen())
    {
        QVector<QStringList> VectorOfNotes;

        QueryConstructor SelectAll;
        SelectAll.setTableName(QStringLiteral("Notes"));
        SelectAll.setOrderByClause("NoteId", Descending);

        QSqlQuery getNotesQuery;

        if( getNotesQuery.exec(SelectAll.constructSelectQuery())) // exec возвращает false
        {
            while (getNotesQuery.next()) // соответственно тоже возвращает false
            {
                QStringList Fields;
                for (int i = 0;i < 9;i++)
                {
                    Fields.push_back(getNotesQuery.value(i).toString());
                }
                VectorOfNotes.push_back(Fields);
            }
        }
        else
        {
            QMessageBox::critical(NULL, QObject::tr("Error"), getNotesQuery.lastError().text()); // no such table. Unable to execute statement
        }

        return VectorOfNotes;
    }
    else
    {
        showIsNotOpenError();
        return QVector<QStringList>();
    }
}

数据库连接：

bool DbManager::connect(const QString & path)
{
    MattyNotesDb = QSqlDatabase::addDatabase("QSQLITE");
    MattyNotesDb.setDatabaseName(path); // path="MattyNotes.sqlite"

    if(QFile::exists(path)) // true
    {
        if (!MattyNotesDb.open()) // open=true, то есть if(false)
        {
            QMessageBox::critical(NULL, QObject::tr("Error"), MattyNotesDb.lastError().text());
            MattyNotesDb.close();

            return false;
        }

        return true;
    }
    else
    {
        return false;
    }
}

提出要求：

QString QueryConstructor::constructSelectQuery()
{
    QString ResultQuery = "";

    if (TableName != "")
    {
        ResultQuery.append("SELECT ");

        if (WhatToSelectFieldNames.isEmpty())
        {
            ResultQuery.append("*");
        }
        else
        {
            for (int i = 0;i < WhatToSelectFieldNames.length()-1;i++)
            {
                ResultQuery.append(" " + WhatToSelectFieldNames[i] + ",");
            }
            ResultQuery.append(WhatToSelectFieldNames.last());
        }
        ResultQuery.append(" FROM " + TableName + constructWhereEqualsClause() + " " + OrderByClause);
    }
    return ResultQuery; // "SELECT * FROM Notes  ORDER BY NoteId DESC; " 
}

UPD： 问题出在文件路径中。如果您手动输入完整路径，则一切正常。

一。

 QString PathToDb = QCoreApplication::applicationDirPath() + "/MattyNotes.sqlite";

该选项最终将 PathToDb 变量设置为 "C:/Users/Matty/Documents/QtCreator/build-MattyNotes-Desktop_Qt_5_7_1_MinGW_32bit-Debug/debug/MattyNo" 文件夹是正确的，但为什么被截断了？

2.

QString PathToDb = QDir::currentPath() + "/MattyNotes.sqlite";

这个选项赋值为“C:/Users/Matty/MattyNotes.sqlite” 一般来说，我想知道中间文件夹去了哪里。

3.

QString PathToDb = QFileInfo(".").absolutePath() + "/MattyNotes.sqlite";

此选项给出“C:/Users/MattyNotes.sqlite”

发生了什么？如何只指定一个相对路径，以便一切都在不同的机器上运行？

还有一个问题：为什么

if(QFile::exists(path)) // true
if (!MattyNotesDb.open()) // open=true, то есть if(false)

如果数据库实际上没有打开，这些行是否返回 true？

有一个类继承了QGroupBox（不知道有没有关系），还有一个类就是简单的为他们存储数据和几个函数。我需要将第二个类的实例传递给第一个类的方法。

MattyGroupBox.h

#ifndef MATTYGROUPBOX_H
#define MATTYGROUPBOX_H

    public QGroupBox
{
public:
    MattyGroupBox();
    //void fillFrame(MattyNote & ThisNote);
    ~MattyGroupBox();
private:
    void buildFrame();
    QLabel* NoteTitleLabel;
    QLabel* NoteTypeLabel;
    QLabel* NoteCrTimeAndDateLabel;
    QLabel* NoteEventTimeAndDateLabel;
    QLabel* NoteTextLabel;
    QSpacerItem* horizontalSpacer_1;
    QSpacerItem* horizontalSpacer_2;
    QSpacerItem* verticalSpacer;
    QPushButton* editNoteButton;
    QPushButton* deleteNoteButton;
    QHBoxLayout* horizontalLayout_1;
    QHBoxLayout* horizontalLayout_2;
    QVBoxLayout *verticalLayout;
    QGridLayout *gridLayout;

};

#endif // MATTYGROUPBOX_H

MattyGroupBox.cpp

#include "stdafx.h"
#include "MattyGroupBox.h"
#include "MattyNote.h"


MattyGroupBox::MattyGroupBox()
{
    buildFrame();
}

//void MattyGroupBox::fillFrame(MattyNote & ThisNote)
//{
    //NoteTitleLabel->setText(ThisNote.getTitle());
    //NoteTypeLabel->setText(ThisNote.getType());
    //NoteTextLabel->setText(ThisNote.getText());    
//}

void MattyGroupBox::buildFrame()
{
    // тут очень много того, из-за чего потребовалось наследовать класс
    // добавление элементов Qt

}

MattyGroupBox::~MattyGroupBox()
{
    delete NoteTitleLabel;
    delete NoteTypeLabel;
    delete NoteCrTimeAndDateLabel;
    delete NoteEventTimeAndDateLabel;
    delete NoteTextLabel;
    delete horizontalSpacer_1;
    delete horizontalSpacer_2;
    delete verticalSpacer;
    delete editNoteButton;
    delete deleteNoteButton;
    delete horizontalLayout_1;
    delete horizontalLayout_2;
    delete verticalLayout;
    delete gridLayout;
}

如果取消注释该方法，则会出现错误：

Error   C2511   'void MattyGroupBox::fillFrame(MattyNote &)': overloaded member function not found in 'MattyGroupBox'
Error   C2061   syntax error: identifier 'MattyNote'

MattyNote.h

#ifndef MATTYNOTE_H
#define MATTYNOTE_H

#include "MattyTime.h"

class MattyNote
{
public:
    MattyNote();
    ~MattyNote();
    void setTitle(const QString & Title);
    void setType(const QString & TypeName);
    void setType(int TypeId);
    void setText(const QString & Text);
    void setEventTime(const QString & EventTime); // Warning! Input format must be: 00:00
    void setEventDate(const QString & EventDate); // Warning! Input format must be: 00.00.0000
    QString getTitle();
    QString getType();
    QString getText();
    QString getEventTime(); // Format: 00:00
    QString getEventDate(); // Format: 00.00.0000
    QString getCrTime(); // Format: 00:00
    QString getCrDate(); // Format: 00.00.0000
    int getTypeId();
    TimeAndDate* getEventTimeAndDate(); // Returns a pointer to TimeAndDate structure containing ints
    TimeAndDate* getCrTimeAndDate(); // Returns a pointer to the TimeAndDate structure containing ints
private:
    int NoteTypeId;
    QString NoteTitle;
    QString NoteType;
    QString NoteText;
    QString NoteEventTime; // Format: 00:00
    QString NoteEventDate; // Format: 00.00.0000
    MattyTime* EventTimeAndDate;  // Any unspecified part equals -1
    MattyTime* CrTimeAndDate;  // Automaticly set in constructor of MattyNote
};

#endif // MATTYNOTE_H

MattyNote.cpp

#include "stdafx.h"
#include "MattyNote.h"
#include "Constants.h"
#include "DbManager.h"

MattyNote::MattyNote()
{
    EventTimeAndDate = new MattyTime();
    EventTimeAndDate->setUserTimeAndDateNull();
    CrTimeAndDate = new MattyTime();
    MattyTime::updateCurrTime();
    CrTimeAndDate->UserTimeAndDate = MattyTime::CurrTime;
}

MattyNote::~MattyNote()
{
    delete EventTimeAndDate;
    delete CrTimeAndDate;
}

void MattyNote::setTitle(const QString & Title)
{
    NoteTitle = Title;
}

void MattyNote::setType(const QString & TypeName)
{
    DbManager* MattyNotesDbManager = new DbManager("MattyNotes.sqlite");
    NoteTypeId = MattyNotesDbManager->getTypeId(TypeName);
    NoteType = TypeName;
    delete MattyNotesDbManager;
}

void MattyNote::setType(int TypeId)
{
    DbManager* MattyNotesDbManager = new DbManager("MattyNotes.sqlite");
    NoteType = MattyNotesDbManager->getTypeName(TypeId);
    NoteTypeId = TypeId;
    delete MattyNotesDbManager;
}

void MattyNote::setText(const QString & Text)
{
    NoteText = Text;
}

void MattyNote::setEventTime(const QString & EventTime)
{
    if (EventTime.length() == Constants::TimeQStringLength && EventTime[2] == Constants::TimeSeparator)
    {
        NoteEventTime = EventTime;
        QStringList TimeTemp = EventTime.split(Constants::TimeSeparator);
        EventTimeAndDate->UserTimeAndDate->hour = TimeTemp[0].toInt();
        EventTimeAndDate->UserTimeAndDate->minute = TimeTemp[1].toInt();
        EventTimeAndDate->UserTimeAndDate->second = 0;
    }
}

void MattyNote::setEventDate(const QString & EventDate)
{
    if (EventDate.length() == Constants::DateQStringLength &&
        EventDate[Constants::PositionOfFirstDateSeparator] == Constants::DateSeparator
        && EventDate[Constants::PositionOfSecondDateSeparator] == Constants::DateSeparator)
    {
        NoteEventDate = EventDate;
        QStringList DateTemp = EventDate.split(Constants::DateSeparator);
        EventTimeAndDate->UserTimeAndDate->day = DateTemp[0].toInt();
        EventTimeAndDate->UserTimeAndDate->month = DateTemp[1].toInt();
        EventTimeAndDate->UserTimeAndDate->year = DateTemp[2].toInt();
        EventTimeAndDate->setUserDayOfWeek();
    }
}

QString MattyNote::getTitle()
{
    return NoteTitle;
}

QString MattyNote::getType()
{
    return NoteType;
}

QString MattyNote::getText()
{
    return NoteText;
}

QString MattyNote::getEventTime()
{
    return NoteEventTime;
}

QString MattyNote::getEventDate()
{
    return NoteEventDate;
}

QString MattyNote::getCrTime()
{
    return CrTimeAndDate->PrintUserTime();
}

QString MattyNote::getCrDate()
{
    return CrTimeAndDate->PrintUserDate();
}

int MattyNote::getTypeId()
{
    return NoteTypeId;
}

TimeAndDate * MattyNote::getEventTimeAndDate()
{
    return EventTimeAndDate->UserTimeAndDate;
}

TimeAndDate * MattyNote::getCrTimeAndDate()
{
    return CrTimeAndDate->UserTimeAndDate;
}

stdafx.h 根本不包含标头，Constants.h、DbManager.h、MattyTime.h 和它们的 cpp 也不会发送到任何地方。

实际上，这里可能有什么问题？一般来说，该项目有 10 个头文件和代码文件，如果您需要其他内容，我会发布。

我不能完全理解 operator() 在类中是如何工作的，以及原则上它与方法有何不同。

也就是说，有什么区别

class ManOlderThan
{
    int m_age;
public:
    ManOlderThan( int age )
    {
        m_age = age;
    };
    bool operator()( Man &man )
    {
        if( man.GetAge() > m_age ) {
            return true;
        }
        else {
            return false;
        }
    };
};

class ManOlderThan
{
    int m_age;
public:
    ManOlderThan( int age )
    {
        m_age = age;
    };
    bool compare( Man &man )
    {
        if( man.GetAge() > m_age ) {
            return true;
        }
        else {
            return false;
        }
    };
};

那怎么调用呢？或者当只有一种方法时是否需要操作员？或者它们是完全不同的东西？

通常，在这种情况下，运算符在向量和 for_each 和 find_if 的上下文中被考虑