Solved Show live data into a table
-
@makopo
What is aGridLayout
? If you meanQGridLayout
, that is aQLayout
.QTableView
is aQWidget
. You can always add aQWidget
to aQLayout
. -
What a silly question of mine! I tried it few hours ang and adding QTableView to QGridLayout did not work. Now it works... Thank you
-
@makopo If it is solved then mark it as solved. So others can give time on other unsolved question 💥😀
-
Unfortunatly the view did not work like expected. I create a data model (derived from QAbstractTableModel) and with this model I can generate a table view. But this view is static and values did not update.
I change, for example, the video mode of the stream and on the console this change is detected. In the table view the initial state is detected and did not change.
I makeQTableView
editable, but I think that this is not the right way for my requirement.I implement the virtual
data
function like this:QVariant DataTableModel::data(const QModelIndex& index, int role) const { if (!index.isValid()) { return QVariant(); } if (index.row() >= m_parameter.size() && index.row() >= m_value.size()) { return QVariant(); } if (role == Qt::DisplayRole || role == Qt::EditRole) { if (index.column() == 0) { return m_parameter.at(index.row()); } if (index.column() == 1) { return m_value.at(index.row()); } } return QVariant(); }
In the main class I create two
QVector
types that stores the values for the table cells.QVector<QString> parameters; Qvector<QString> values; parameters.append("Video mode"); values.append(QVariant(m_displayMode->GetDisplayMode()).toString()); m_tableDataModel->AddData(parameters, values); m_tableView->setModel(m_tableDataModel);
As descipted I get the initial video mode, but after changing the mode the state is not updated.
Is there a restiction with the data types and the update process? -
@makopo said in Show live data into a table:
Is there a restiction with the data types and the update process?
Of course, adding something to a vector notifies nobody. If you'd kept an
int
and changed it, the result'd be the same. To add to the model define youraddRow
or alike and thereafter follow the documentation. There's a battery of signals that the model must emit so the view gets notified of changes -beginInsertRows
,endInsertRows
and so on. -
On addition to @kshegunov you also need to re-implement setData so that you can properly notify when data changes.
-
I did not understand how to implement
insertRows()
correctly and it also looks like that the function is not called. Because theQAbstractTableModel
did not work, I rebuild the Qt tutorial which uses theQAbstractListModel
.In
insertRows()
I callbeginInsertRows()
, than I run the loop and than I callendInsertRows()
.bool DataTableModel::insertRows(int position, int rows, const QModelIndex& parent) { beginInsertRows(QModelIndex(), position, position + rows - 1); for (int x = 1; x <= 10; ++x) { m_stringList.push_back(QString::number(x)); } endInsertRows(); qDebug() << "insertRows is called."; return true; }
As result I get an empty List. On console I can also see that the function is not called. So my question is, how to handle insertRows() function? Did
stringList.insert(position, "");
from the Model/View Programming tutorial only reservs an empty line? I thought that there is the entry-point where I have to insert the data. -
@makopo
YourinsertRows()
is called with aposition
to start the insert from and a number ofrows
to insert there. But all you do is ignore these and append 10 rows. You need to respect and act on the parameters. (Same btw fordeleteRows()
.) The newly inserted rows should be blank for this call. -
@JonB
Thank you. I rewrote the loop as recommended in the Model/View Programming tutorial.beginInsertRows(QModelIndex(), position, position + rows - 1); for (int row = 0; row < rows; ++row) { m_stringList.insert(position, ""); } endInsertRows(); qDebug() << "insertRows is called.";
As I can see on the console
insertRows()
is not called. -
@makopo
? Why/when do you expect it to be called? You have to call it if you wish to insert some rows. (And again fordeleteRows()
.) -
insertRows(int row, int count, const QModelIndex &parent = QModelIndex())
is virtual. I thought it is called automatically?As I understand now
m_stringList.insert(position, "");
only reservs an empty row and I have to add data to the table outside the model class? -
@makopo
Thevirtual
just means that if anything callsQAbstractTableModel::insertRows()
--- even if it knows nothing about your derived class --- the implementation code you have written will be called.The outside world will call
insertRows()
when it wants/needs to. The outside world will do that with no knowledge that you have implemented it viam_stringList.insert()
. The outside world will callsetData()
for the desired column values on newly inserted row(s) after it has calledinsertRows()
. -
@JonB
That was not clear for me. I did not call theheaderData(...)
anddata(...)
function. I only generate a instance of the model class, set the model to the view and get a table. Thought thatsetData(...)
andinsertRows(...)
works on the same way.So as I understand from your last post, I have to do something like this:
//QMainClass.cpp m_tableDataModel->insertRows(0, 1, QModelIndex()); m_tableDataModel->setData(QModelIndex(), QParameterList(), QValueList(), 2); //valuelist is a vector and stores data that should be overwritten in the view m_tableView->setModel(m_tableDataModel);
I'am sry. As a beginner the principle of table view is hard to understand.
-
@makopo
Those are the right calls. But you'll have to work a bit on all your parameters tosetData()
. If you have multiple columns (I don't know if you do) you'll have to callsetData()
for each one. -
A QTableView is just a widget showing your model as a table. Nothing more.
From the looks of it, you did not understand that the model is a wrapper on top of your data structure. From what you wrote it's a QStringList. So you have a model with a single column and as many rows as your string list.
The setData method shall be called to modify the data of one element of your data structure.
If you want to initialise your model with a ready made list, add a method for that.
Note that if your data structure is a QStringList you might as well use the QStringListModel class.
-
I think I understand the principle of a model. Because of this I didn't understand why in this example an empty string is inserted. I think this little for loop is my problem. Why they insert data here?
bool StringListModel::insertRows(int position, int rows, const QModelIndex &parent) { beginInsertRows(QModelIndex(), position, position+rows-1); for (int row = 0; row < rows; ++row) { stringList.insert(position, ""); //empty strings are inserted in every row (inserting data alike)? } endInsertRows(); return true; }
In my project I use two columns. Column 0 includes labels and is fixed, so I think I didn't need
SetData()
for the first column. Column 1 gets values of different types and this values should be constantly updated. For both columns I use aQVector<QString>
. To add data to the vector I wrote two functions:QParameterList()
andQValueList()
. I also implement a functionAddData()
that has aQVector<QString>
type as parameter.void DataTableModel::AddData(const QVector<QString>& parameter) { m_parameter = parameter; }
In my
QMainClass
I callAddData()
and with this I generate the first column (column with the fixed values). Now I call the reimplementedSetData()
function and insert (only for test purposes) data to one cell. I got an empty cell. I can fill all cells in column 1 manually, I get an empty column. I think this happens because the empty string overrides the value, I inserted withSetData(...)
?QVariant DataTableModel::SetData(const QModelIndex& index, const QVariant& value, int role) { if (role == Qt::DisplayRole && index.row() == 0 && index.column() == 1) { return QString(value.toString()); } return QVariant(); } // QMainClass.cpp QVariant value = QString("Test"); m_tableDataModel->InsertRows(QModelIndex(), 0, 3); m_tableDataModel->AddData(QParameterList()); m_tableDataModel->SetData(QModelIndex(), value, 2); m_tableView->setModel(m_tableDataModel);
-
When you add rows, your data structure should contain something that can be returned to the view. Still in the case of your string list, you shall adjust the size of the list and then put some meaningful default data in the new empty spots. In this case empty strings.
Your SetData method does not make sense. By the way, the correct name is setData. Casing is important.
-
Thank you. I will do a next try...:
//DataTableModel.cpp bool DataTableModel::setData(const QModelIndex& index, const QVariant& value, int role) { if (!index.isValid() && role != Qt::EditRole) { return false; } //change only values in column 1 if (index.column() == 1) { m_value.replace(index.row(), value.toString()); emit dataChanged(index, index, { role }); return true; } } bool DataTableModel::insertRows(int row, int count, const QModelIndex& parent) { beginInsertRows(QModelIndex(), row, row + count - 1); for (int i = 0; i < count; ++i) { m_value.insert(row, ""); } endInsertRows(); return true; } //QMainClass.cpp - called when button is clicked. void QMainClass:QAddTableContent() { QVariant values(QValueList()); //convert QList to QVariant m_tableDataModel->insertRows(0, 5, QModelIndex()); //insert 5 rows m_tableDataModel->AddData(QParameterList()); m_tableDataModel->setData(QModelIndex(), values, 2); }
With this I get a table with 5 rows and 2 columns. The left column shows a list of parameters. The right column is empty.
In the model I set theQt::ItemIsEditable flag
. With this I can edit the right column. I can write into the cells and the new values are stored temporary. Because of this I think thesetData()
function should work correct. Unfortunatly, when the program runs, the right column remains empty (because of the inserted empty string in insertRows?). Are the data inserted on a wrong way? -
How is your data method implemented currently ?
-
This is my data method:
QVariant DataTableModel::data(const QModelIndex& index, int role) const { if (!index.isValid()) { return QVariant(); } if (index.row() >= m_parameter.size() && index.row() >= m_value.size()) { return QVariant(); } if (role == Qt::DisplayRole || role == Qt::EditRole) { switch (index.column()) { case 0: return m_parameter.at(index.row()); break; case 1: return m_value.at(index.row()); break; default: Q_ASSERT(false); } } return QVariant(); }