Creating custom QAbstractItemModel from comma seperated text file - qt

Question

I have this issue that my Qtableview gets extreme slowly after inserting 100.000 rows and specially using multiple select.
So after some reasearch I have decided to use my own model that inherits from QAbstractItemModel. But the issue is I have no clue how to use it since, the text file can change. fx. I can load a file with 5 columns and 50.000 rows, and after sometime it can have 15 columns and 10.000 rows.
the data does not need to be changed, so its only read only.
Anyone can help me with this problem?
My "empty" custom model is here
#include "customabstractmodel.h"
CustomAbstractModel::CustomAbstractModel(QObject *parent)
: QAbstractItemModel(parent)
{
}
QVariant CustomAbstractModel::headerData(int section, Qt::Orientation orientation, int role) const
{
// FIXME: Implement me!
}
bool CustomAbstractModel::setHeaderData(int section, Qt::Orientation orientation, const QVariant &value, int role)
{
if (value != headerData(section, orientation, role)) {
// FIXME: Implement me!
emit headerDataChanged(orientation, section, section);
return true;
}
return false;
}
QModelIndex CustomAbstractModel::index(int row, int column, const QModelIndex &parent) const
{
// FIXME: Implement me!
}
QModelIndex CustomAbstractModel::parent(const QModelIndex &index) const
{
// FIXME: Implement me!
}
int CustomAbstractModel::rowCount(const QModelIndex &parent) const
{
if (!parent.isValid())
return 0;
// FIXME: Implement me!
}
int CustomAbstractModel::columnCount(const QModelIndex &parent) const
{
if (!parent.isValid())
return 0;
// FIXME: Implement me!
}
QVariant CustomAbstractModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
return QVariant();
// FIXME: Implement me!
return QVariant();
}
bool CustomAbstractModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
if (data(index, role) != value) {
// FIXME: Implement me!
emit dataChanged(index, index, QVector<int>() << role);
return true;
}
return false;
}
Qt::ItemFlags CustomAbstractModel::flags(const QModelIndex &index) const
{
if (!index.isValid())
return Qt::NoItemFlags;
return Qt::ItemIsEditable; // FIXME: Implement me!
}
bool CustomAbstractModel::insertRows(int row, int count, const QModelIndex &parent)
{
beginInsertRows(parent, row, row + count - 1);
// FIXME: Implement me!
endInsertRows();
}
bool CustomAbstractModel::insertColumns(int column, int count, const QModelIndex &parent)
{
beginInsertColumns(parent, column, column + count - 1);
// FIXME: Implement me!
endInsertColumns();
}
bool CustomAbstractModel::removeRows(int row, int count, const QModelIndex &parent)
{
beginRemoveRows(parent, row, row + count - 1);
// FIXME: Implement me!
endRemoveRows();
}
bool CustomAbstractModel::removeColumns(int column, int count, const QModelIndex &parent)
{
beginRemoveColumns(parent, column, column + count - 1);
// FIXME: Implement me!
endRemoveColumns();
}
Edit #1 Csv data (Not real information, randomized)
name,phone,email,address,city,zip
Chavez, Lisandra F.,1-498-913-8181,ac.fermentum.vel#semperrutrumFusce.org,Ap #123-1044 Sed Rd.,Drayton Valley,21833
Humphrey, Briar W.,1-583-466-4027,Morbi.accumsan.laoreet#Loremipsumdolor.net,Ap #642-6497 Id Rd.,Lochgilphead,16394
Benson, Tasha H.,1-898-918-7872,consequat#enimEtiam.ca,P.O. Box 197, 4720 Ipsum. St.,Telford,56688
Emerson, Susan P.,1-190-818-1919,dignissim#liberoatauctor.ca,P.O. Box 482, 7813 Dolor. Ave,San Antonio,M8C 7F6
Dunn, Alexander U.,1-222-379-2231,libero.Donec.consectetuer#nonegestasa.ca,803-958 Lectus Rd.,Raleigh,74078

Answer 1

Assuming that we read the whole file into memory, I would implement the model (subclass from QAbstractTableModel) in the following way:
CustomAbstractModel::CustomAbstractModel(const QString &filePath,
QObject *parent)
:
QAbstractTableModel(parent)
{
// Parse the file and store its data in an internal data structure
QFile file(filePath);
if (file.open(QIODevice::ReadOnly))
{
QTextStream in(&file);
while (!in.atEnd())
{
// Assuming that m_data is a std::vector<QString>
m_data.emplace_back(in.readLine());
}
}
}
QVariant CustomAbstractModel::headerData(int section,
Qt::Orientation orientation,
int role) const
{
if (orientation == Qt::Horizontal && role == Qt::DisplayRole &&
!m_data.empty())
{
// Read the column names from the first line
const QString &firstLine = m_data.front();
QStringList headers = firstLine.split(',');
return headers.at(section);
}
}
int CustomAbstractModel::rowCount(const QModelIndex &parent) const
{
if (!m_data.empty())
{
return m_data.size() - 1; // First line is the column names data
}
return 0;
}
int CustomAbstractModel::columnCount(const QModelIndex &parent) const
{
if(!m_data.empty())
{
const QString &firstLine = m_data.front();
return firstLine.count(",") + 1;
}
return 0;
}
QVariant CustomAbstractModel::data(const QModelIndex &index, int role) const
{
if (m_data.empty() && role == Qt::DisplayRole)
{
// First line is the header data.
const QString &line = m_data[index.row() + 1];
QStringList columnData = firstLine.split(',');
return columnData.at(index.column());
}
return QVariant();
}