来自 C++ 的 QStandardItemModel 在 QtQuick / QML TableView 中不可见

Question

I have subclassed QStandardItemModel and want to link it with TableView in QML. But data from QStandardItemModel is not visible in TableView.

With role set to "display" in tableview I am able to see first column so I have re-implemented roleNames() function in my class but still no success. I am not sure how to link roleNames enum with column in QStandardItemModel?

class AuditLogsModel : public QStandardItemModel
{
    Q_OBJECT
    QList<QStandardItem*> row;
public:
    enum AuditRoles
    {
        DateTimeRole = Qt::UserRole + 1,
        UsernameRole,
        ApplicationRole,
        CategoryRole,
        DescriptionRole
    };
...

Implementation (C++) source

AuditLogsModel::AuditLogsModel(QObject *parent)
    : QStandardItemModel(parent)
{
    row.clear();
    loadData();
    setColumnMapping();
}

void AuditLogsModel::setColumnMapping()
{
    setData(index(0,0), "DateTime", AuditRoles::DateTimeRole);
    setData(index(0,1), "Name", AuditRoles::UsernameRole);
    setData(index(0,2), "Application", AuditRoles::ApplicationRole);
    setData(index(0,3), "Category", AuditRoles::CategoryRole);
    setData(index(0,4), "Description", AuditRoles::DescriptionRole);
}

QHash<int, QByteArray> AuditLogsModel::roleNames() const
{
    QHash<int, QByteArray> roleNameMap;
    roleNameMap[DateTimeRole] = "DateTime";
    roleNameMap[UsernameRole] = "Name";
    roleNameMap[ApplicationRole] = "Application";
    roleNameMap[CategoryRole] = "Category";
    roleNameMap[DescriptionRole] = "Description";

    return roleNameMap;
}

void AuditLogsModel::loadData()
{
    QFile file(AUDIT_LOG_PATH);
    if( file.exists() == false )
    {
        syslog(LOG_ERR,qPrintable(QString("Audit log file: %1 does not exist").arg(AUDIT_LOG_PATH)));
        return;
    }

    if (file.open(QIODevice::ReadOnly))
    {
        QTextStream in(&file);

        QString line;
        QJsonObject logEntry;
        while(!in.atEnd()) {

            line = in.readLine();
            logEntry = (QJsonDocument::fromJson(line.toStdString().c_str())).object();

            row.append(new QStandardItem(logEntry["Date-time"].toString()));
            row.append(new QStandardItem(logEntry["username"].toString()));
            row.append(new QStandardItem(logEntry["App_name"].toString()));
            row.append(new QStandardItem(logEntry["event_category"].toString()));
            row.append(new QStandardItem(logEntry["event_desc"].toString()));

            appendRow(row);
            row.clear();
        }
        file.close();
    }
}

QML code

 TableView {
        id: auditLogTable
        [geometry]   
        model: auditLogModelObj

        TableViewColumn {
            role: "DateTime"
            title: qsTr("Local Time")
            width: auditLogTable.width * 0.15
        }

        TableViewColumn {
            role: "Name"
            title: qsTr("Created By")
            width: auditLogTable.width * 0.1
        }

        TableViewColumn {
            role: "Application"
            title: qsTr("app name")
            width: auditLogTable.width * 0.40
        }

        TableViewColumn {
            role: "Category"
            title: qsTr("Category")
            width: auditLogTable.width * 0.2
        }

        TableViewColumn {
            role: "Description"
            title: qsTr("Detail")
            width: auditLogTable.width * 0.40
        }
    }

Answer 1

I do not understand what you tried to do in setColumnMapping(), and you do not need to use roleNames() either. In addition, the TableView that you use only accepts model of list type, in this case the roles will be the columns, considering that the solution is:

*.h

class AuditLogsModel : public QStandardItemModel
{
public:
    enum AuditRoles{
        DateTimeRole = Qt::UserRole + 1,
        UsernameRole,
        ApplicationRole,
        CategoryRole,
        DescriptionRole
    };
    AuditLogsModel(QObject *parent=nullptr);
    void loadData();
};

*.cpp

AuditLogsModel::AuditLogsModel(QObject *parent):
    QStandardItemModel(parent)
{
    QHash<int, QByteArray> roles;
    roles[DateTimeRole] = "DateTime";
    roles[UsernameRole] = "Name";
    roles[ApplicationRole] = "Application";
    roles[CategoryRole] = "Category";
    roles[DescriptionRole] = "Description";
    setItemRoleNames(roles);
}

void AuditLogsModel::loadData()
{
    QFile file(AUDIT_LOG_PATH);
    if(!file.exists() )
    {
        syslog(LOG_ERR,qPrintable(QString("Audit log file: %1 does not exist").arg(AUDIT_LOG_PATH)));
        return;
    }

    if (file.open(QIODevice::ReadOnly))
    {
        QTextStream in(&file);
        QString line;
        QJsonObject logEntry;
        while(!in.atEnd()) {
            QStandardItem *row = new QStandardItem;
            line = in.readLine();
            logEntry = (QJsonDocument::fromJson (line.toStdString().c_str())).object();
            row->setData(logEntry["Date-time"].toString(), DateTimeRole);
            row->setData(logEntry["username"].toString(), UsernameRole);
            row->setData(logEntry["App_name"].toString(), ApplicationRole);
            row->setData(logEntry["event_category"].toString(), CategoryRole);
            row->setData(logEntry["event_desc"].toString(), DescriptionRole);
            appendRow(row);
        }
        file.close();
    }
}