I don't know why I have trouble removing all rows and sub rows from qtreeview
I'm using QStandardItemModel as the model. Now here is my code that doesn't work.
What could be the problem?
QModelIndex FirstQModelIndex;
QModelIndex parentQModelIndex;
int iMdlChidCound = m_model->hasChildren();
if(iMdlChidCound > 0)
{
// only if there at list 1 row in the view
FirstQModelIndex = m_model->item(0,0)->index();
QStandardItem* feedItem = m_model->itemFromIndex(FirstQModelIndex);
// get the parent of the first row its the header row
QStandardItem* parentItem = feedItem->parent();
// here im getting exception
int parent_rows= parentItem->hasChildren();
parentQModelIndex = m_model->indexFromItem(parentItem);
// now i like to delete all the rows under the header , and its dosnt work
if(parent_rows>0)
{
bool b = feedItem->model()->removeRows(0,y,parentQModelIndex);
}
}
It seems like a lot of what you're doing is superfluous. If your only goal is to remove all the rows from the model, you could probably just use QStandardItemModel::clear
In your code you're jumping between the model and the items in a way you don't have to.
if(m_model->hasChildren()) {
m_model->removeRows(0, m_model->rowCount());
}
That should do what you're seeking.
QStandardItemModel::clear()
Which clears all the items including the header rows.
Related
void IdListForTrain::SetListIdInList(QStringList IdList)
{
QTableWidgetItem *item=nullptr;
for(int index=0;index<IdList.count();index++)
{
ui->Id_tableWidget->insertRow(index);
for(qint32 columnIndex=0;columnIndex<=1;columnIndex++)
{
item = new QTableWidgetItem;
if(columnIndex==0)
{
ui->Id_tableWidget->setItem(index,columnIndex,item);
item->setText("00:00:00");
}
if(columnIndex==1)
{
ui->Id_tableWidget->setItem(index,columnIndex,item);
item->setText(IdList.at(index));
}
QString tmp1 = ui->Id_tableWidget->item(index,1)->text();
QString tmp = item->text();
}
}
}
Hi! I am new to Qt and I'm facing a problem. I was asked to create a tablewidget with the effective date of train Ids in one column and the names of the trains in another column,I did this code to the best of my knowledge but I can't set or access the data in the widget in the line eventhough the code doesnt give any errors but it crashes everytime I open the application window at this line,
QString tmp1 = ui->Id_tableWidget->item(index,1)->text();
I'm not sure what the reason is.
Let look at first iteration - index=0 and columnIndex=0.
You go through if(columnIndex==0) condition and set item to
QTableWidget's row = 0 (index) and column = 0 (columnIndex)
Second condition skipped
You try to access item at row = 0 (index) and column = 1 with code QString tmp1 = ui->Id_tableWidget->item(index,1)->text();. But at this time you have no item assigned to that column
That's all!
I am working with a qtableview that is filled by a model and has two columns. I can get the contents of a selected cell no problem but only want the contents of the second column even if the first column is clicked.
void MainWindow::on_tableView_clicked(const QModelIndex &index)
{
QString cellText;
if (index.isValid()) {
cellText = index.data().toString();
}
ui->lineEdit->setText(cellText);
}
the index looks like this for column 0:
QModelIndex(7,0,0x55f2e5d06b00,QStandardItemModel(0x55f2e5d09740))
And for column 1:
QModelIndex(8,1,0x55f2e5d06b00,QStandardItemModel(0x55f2e5d09740))
I tried to find a way to change the index for the cell that is clicked but I think there is no way to change it directly and I can not seem to find a way to tell my function to always use column 1 the second column.
Thanks for your time.
Code edited to reflect comment 1 below
{
QString cellText;
if (index.isValid()) {
QModelIndex idx = index;
idx = idx.sibling(idx.row(), 1);
cellText = idx.data().toString();
}
ui->lineEdit->setText(cellText);
}```
I'm trying to put a MySQL table into a treeView.
Each entry has three values in the database - id, text, parentId.
This treeView needs to be editable so I really like the QSqlTableModel approach, as the functionality to save back to database is already built in.
Now, the treeView is showing all entries in the same line, of course, and I need a hierarchy. What would be the best way to build this hierarchy, while maintaining the editing and saving capabilities?
(I'm using MySQL.)
mainwindow.h
private: QSqlTableModel* goalModel;
mainwindow.cpp
(this makes a flat table hierarchy. the table is filtered based on which entry is clicked in another table)
void MainWindow::on_tableViewGoals_clicked(const QModelIndex &index)
{
goalModel = new QSqlTableModel(this);
goalModel->setTable("goals");
//Gets the id from the clicked entry to use as filter
QString idGoals = index.sibling(row,0).data().toString();
goalModel->setFilter( "id_goals=" + idGoals );
goalModel->setEditStrategy(QSqlTableModel::OnRowChange);
goalModel->select();
ui->treeView->setModel(goalModel);
...
I tried this. It's wrong, but I don't really know why. (the third column contains the parentId value, if the entry has it)
for (int row = 0; row < goalModel->rowCount(); ++row)
{
//if the entry has a value over 0 in the parentId column
if (goalModel->index(row,2).data().toInt() > 0)
{
//get number in column 2
int parentId;
parentId = goalModel->index(row,2).data().toInt();
QModelIndex newChild = goalModel->index(row,0);
//find QModelIndex row with matching number in column 0
for (int row = 0; row < goalModel->rowCount(); ++row)
{
if (goalModel->index(row,0).data().toInt() == parentId )
{
//make this entry that entry's child
QModelIndex newParent = goalModel->index(row,0);
newChild = goalModel->index(0,0,newParent);
}
}
}
}
All indexes are already made, so no need to make new ones, just assign a parent to all those who have one. How best to do that?
I have implemented a lazily populated treeview by subclassing QAbstractItemModel. The implementation looks something like:
https://gist.github.com/gnufied/db9c4d805e2bb24d8c23
(I am not pasting code inline, so as to mess with messaging)
It is basically a tree representation of hierarchical data stored in table. Now, I want users to be able to sort the rows based on columns. Where columns are, "count" or "reference count". These values are basically integers.
The implementation on its own works, until I throw in QSortFilterProxyModel and I start to get lots of empty rows in the view. The hard problem is, this tends to happen only when I have lots of rows (like thousands or so).
The code for implementing sorting proxy is:
rootItem = RBKit::SqlConnectionPool::getInstance()->rootOfSnapshot(snapShotVersion);
model = new RBKit::HeapDataModel(rootItem, this);
proxyModel = new SortObjectProxyModel(this);
proxyModel->setSourceModel(model);
ui->treeView->setModel(proxyModel);
ui->treeView->setSortingEnabled(true);
I have subclassed QSortFilterProxyModel class and subclass implementation is really simple:
https://gist.github.com/gnufied/115f1a4fae3538534511
The documentation does say -
"This simple proxying mechanism may need to be overridden for source models with more complex behavior; for example, if the source model provides a custom hasChildren() implementation, you should also provide one in the proxy model."
But beyond that, I am not sure - what I am missing.
So, I think I have found the solution and the fix appears to be reimplementing fetchMore in proxy model subclass, because inserted rows reported by source model, do not match place where rows actually exist in view (Rows in view are owned by proxy model), so this seems to have fixed it for me:
#include "sortobjectproxymodel.h"
SortObjectProxyModel::SortObjectProxyModel(QObject *parent) :
QSortFilterProxyModel(parent)
{
}
bool SortObjectProxyModel::hasChildren(const QModelIndex &parent) const
{
const QModelIndex sourceIndex = mapToSource(parent);
return sourceModel()->hasChildren(sourceIndex);
}
int SortObjectProxyModel::rowCount(const QModelIndex &parent) const
{
const QModelIndex sourceIndex = mapToSource(parent);
return sourceModel()->rowCount(sourceIndex);
}
bool SortObjectProxyModel::canFetchMore(const QModelIndex &parent) const
{
if(!parent.isValid())
return true;
else {
const QModelIndex sourceIndex = mapToSource(parent);
return sourceModel()->canFetchMore(sourceIndex);
}
}
void SortObjectProxyModel::fetchMore(const QModelIndex &parent)
{
if (parent.isValid() && parent.column() == 0) {
int row = parent.row();
int startRow = row + 1 ;
const QModelIndex sourceIndex = mapToSource(parent);
RBKit::HeapItem *item = static_cast<RBKit::HeapItem *>(sourceIndex.internalPointer());
if (!item->childrenFetched) {
qDebug() << "Insert New Rows at :" << startRow << " ending at : " << startRow + item->childrenCount();
beginInsertRows(parent, startRow, startRow + item->childrenCount());
item->fetchChildren();
endInsertRows();
}
}
}
Thank you for responding. At this point I really don't care about resorting rows that were lazy loaded (when a node was expanded), so I went ahead and disabled sortingEnabled and disabled dynamicSortFiltertoo.
The new code looks like:
rootItem = RBKit::SqlConnectionPool::getInstance()->rootOfSnapshot(snapShotVersion);
model = new RBKit::HeapDataModel(rootItem, this);
proxyModel = new SortObjectProxyModel(this);
proxyModel->setSourceModel(model);
proxyModel->sort(2, Qt::DescendingOrder);
proxyModel->setDynamicSortFilter(false);
ui->treeView->setModel(proxyModel);
That still leaves with empty rows though.
In my oppinion You don't need to subclass QSortFilterProxyModel for sorting on the top layer. If sortingEnabled == true for your view then the view will perform sorting on the proxy model, which is not desirable as the model should sort itself. What you need is to to call proxyModel->sort(desiredColumn) and that will display your model sorted in the view without altering your data. By default the QSortFilterProxyModel has its dynamicSortFilter property on, which will cause the proxy model to automatically re-sort when data changes or row is inserted or removed. I didn't see emitting dataChanged signal anywhere in your HeapDataModel, so maybe that could be a hint for you to get dynamically sorted rows. If you need to sort subitems then it goes little more complicated and then maybe you'll need to subclasss QSortFilterProxyModel. These model-view abstractions are hard to learn but once you get it you can do miracles rapidly.
rootItem = RBKit::SqlConnectionPool::getInstance()->rootOfSnapshot(snapShotVersion);
model = new RBKit::HeapDataModel(rootItem, this);
proxyModel = new SortObjectProxyModel(this);
proxyModel->setSourceModel(model);
proxyModel->sort(column);
ui->treeView->setModel(proxyModel);
How can I implement this code I have for a qTreeWidget for a qTreeView?
for (const auto & i : names) {
QTreeWidgetItem * item = new QTreeWidgetItem(ui->treeWidget);
item->setText(0, QString::fromStdString(i));
ui->treeWidget->addTopLevelItem(item);
const std::unordered_map<std::string, double> map = m_reader.getMapFromEntry(i);
for (const auto & j : map) {
QTreeWidgetItem * item2 = new QTreeWidgetItem();
item2->setText(0,QString::fromStdString(j.first));
item2->setText(1,QString::number(j.second));
item->addChild(item2);
}
}
I have a model and a treeView, like this:
m_model = new QStandardItemModel(m_reader.getAllNames().size(),2,this);
ui->treeView->setModel(m_model);
I tried this, but that only shows one column:
QStandardItem * parentItem = m_model->invisibleRootItem();
for (const auto & i : names) {
QStandardItem * item = new QStandardItem(QString::fromStdString(i));
parentItem->appendRow(item);
const std::unordered_map<std::string, double> map = m_reader.getMapFromEntry(i);
for (const auto & j : map) {
QList<QStandardItem *> rowItems;
rowItems << new QStandardItem(QString::fromStdString(j.first));
rowItems << new QStandardItem(QString::number(j.second));
item->appendRow(rowItems);
}
}
With the treeWidget, I had so set the columnCount, like this:
ui->treeWidget->setColumnCount(2);
But treeView does not have a method like this.
So, to summarize: How can I implement a TreeView with more than one column?
EDIT:
To clarify, I want something like this:
|-A
| |-B-C
| |-D-E
where A is the parent and B,C,D,E the children, with B,D being in column 0 and C,E in column 1.
Hope this helps!
To support multiple columns, the model must contain data for multiple columns.
So in some sense, columns are a property of the model, not the view. Views then can decide to hide or rearrange certain columns (For example, a QListView always only shows the first column, while one can hide or reorder columns in a QTableView).
As you use QStandardItemModel, its documentation should give a few hints how to create multiple columns.
E.g., look at this example from the documentation:
QStandardItemModel model(4, 4);
for (int row = 0; row < 4; ++row) {
for (int column = 0; column < 4; ++column) {
QStandardItem *item = new QStandardItem(QString("row %0, column %1").arg(row).arg(column));
model.setItem(row, column, item);
}
}
It creates a model with 4 initial rows and columns each, and then fills it with items via setItem().
Alternatively, you can pass a list of items to QStandardItemModel::appendRow(), with an item for each column:
QList<QStandardItem*> items;
items.append(new QStandardItem(tr("One"));
items.append(new QStandardItem(tr("Two"));
model->appendRow(items);
This adds a new row with "One' in the first column and "Two" in the second. For even more ways to deal with multiple columns, see the QStandardItemModel docs.
Note: QTreeView expects the same number of columns on all levels of the hierarchy, so one should fill rows with empty items for the unused columns if need be.
Just an addition to answer by Frank Osterfeld:
QTreeView displays all columns of subtables inserted into top level QStandardItems. You just have to "force" it to show additional columns by inserting dummy QStandardItems into top-level table. Example:
QStandardItemModel *objectTreeModel = new QStandardItemModel(NULL);
QStandardItem *mainItem = new QStandardItem(tr("Main Item"));
QStandardItem *subItem1 = new QStandardItem(tr("Sub-Item 1"));
QStandardItem *subItem2 = new QStandardItem(tr("Sub-Item 2"));
mainItem->appendRow(QList<QStandardItem *>() << subItem1 << subItem2);
QStandardItem *dummyItem = new QStandardItem();
objectTreeModel->appendRow(QList<QStandardItem *>() << mainItem << dummyItem );
Now you will be able to see 2 columns and if you expand mainItem, both subitems will be visible.