Why do I get false when I try to insert a record to a QSqlTableModel in QT?

Question

I'm creating a QSqlRecord object and then I set the values to that QSqlRecord object. But even if I insert the QSqlRecord object to the QSqlTableModel object, the function of inserting records, returns false.

I have this C++ code and it create a QSqlRecord object and set the values. It setting the values in the correct indexed order as how the table was created.

/* Insert data */
int column_index = 0; /* Index 0 is the ID  column */
QSqlRecord record;
qDebug() << CALIBRATION_COLUMNS.at(column_index).first;
record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, 1); /* ID */
qDebug() << CALIBRATION_COLUMNS.at(column_index).first;
record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, calibration_id);
qDebug() << CALIBRATION_COLUMNS.at(column_index).first;
record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, calibration_comment);
qDebug() << CALIBRATION_COLUMNS.at(column_index).first;
record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, calibration_date_time);
for(int i = 0; i < 12; i++){
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, min_adc[i]);
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, max_adc[i]);
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, bias_adc[i]);
}
for(int i = 0; i < 5; i++){
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, min_dadc[i]);
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, max_dadc[i]);
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, bias_dadc[i]);
}
for(int i = 0; i < 2; i++)
    record.setValue(CALIBRATION_COLUMNS.at(column_index++).first, pulses_per_revolution_encoder[i]);

/* -1 means append record */
qDebug() << calibration_model->insertRecord(-1, record);
qDebug() << calibration_model->lastError().text();
qDebug() << "Submit:";
if(!calibration_model->submitAll()){
    qDebug() << calibration_model->lastError().text();
    return DATABASE_STATUS_COULD_NOT_INSERT_ROW;
}
return DATABASE_STATUS_OK;

But even if I insert the record, this function calibration_model->insertRecord(-1, record); returns false but the calibration_model->submitAll() returns true.

Output:

"ID"
"calibration_id"
"calibration_comment"
"calibration_date_time"
false
"No Fields to update"
Submit:

So tell me. What I'm I doing wrong here?

I'm getting the error No Fields to update, but what does that mean? I have an empty table and I just want to append with one row.

Answer 1

Not sure why you're getting that error. I have a small example for QSqlTableModel. Let me put it here. Maybe you could compare with your code.

main.cpp

#include <QApplication>
#include "mysqltablemodel.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("mydb");

    if(!db.open()) {
        qDebug() << db.lastError().text();
        return 0;
    }

    QSqlQuery query(db);

    if(!query.exec("DROP TABLE IF EXISTS mytable")) {
        qDebug() << "create table error: " << query.lastError().text();
        return 0;
    }

    if(!query.exec("CREATE TABLE IF NOT EXISTS mytable \
                   (id integer primary key autoincrement, name varchar(15), salary integer)")) {
        qDebug() << "create table error: " << query.lastError().text();
        return 0;
    }

    MySqlTableModel *model = new MySqlTableModel(0, db);
    model->setTable("mytable");
    model->setEditStrategy(QSqlTableModel::OnManualSubmit);
    model->select();

    QSqlRecord rec = model->record();
    rec.setValue(1, "peter");
    rec.setValue(2, 100);
    qDebug() << model->insertRecord(-1, rec);
    rec.setValue(1, "luke");
    rec.setValue(2, 200);
    qDebug() << model->insertRecord(-1, rec);

    if(model->submitAll()) {
        model->database().commit();
    } else {
        model->database().rollback();
        qDebug() << "database error: " << model->lastError().text();
    }

    query.exec("SELECT name, salary FROM mytable");

    while (query.next()){
        QString name = query.value(0).toString();
        int salary = query.value(1).toInt();
        qDebug() << name << salary;
    }

    return app.exec();
}

mysqltablemodel.h

#ifndef MYSQLTABLEMODEL_H
#define MYSQLTABLEMODEL_H

#include <QSqlTableModel>
#include <QSqlRecord>
#include <QSqlError>
#include <QSqlQuery>
#include <QDebug>

class MySqlTableModel : public QSqlTableModel
{
    Q_OBJECT

public:
    MySqlTableModel(QObject *parent = 0, QSqlDatabase db = QSqlDatabase());
    QVariant data(const QModelIndex &index, int role=Qt::DisplayRole ) const;

protected:
    QHash<int, QByteArray> roleNames() const;

private:
    QHash<int, QByteArray> roles;
};

#endif // MYSQLTABLEMODEL_H

mysqltablemodel.cpp

#include "mysqltablemodel.h"

MySqlTableModel::MySqlTableModel(QObject *parent, QSqlDatabase db): QSqlTableModel(parent, db) {}

QVariant MySqlTableModel::data ( const QModelIndex & index, int role ) const
{
    if(index.row() >= rowCount()) {
        return QString("");
    }
    if(role < Qt::UserRole) {
        return QSqlQueryModel::data(index, role);
    }
    else {
        return QSqlQueryModel::data(this->index(index.row(), role - Qt::UserRole), Qt::DisplayRole);
    }
}

QHash<int, QByteArray> MySqlTableModel::roleNames() const
{
    QHash<int, QByteArray> roles;
    roles[Qt::UserRole + 1] = "name";
    roles[Qt::UserRole + 2] = "salary";
    return roles;
}