This is how our example model looks so far: Qt automatically keeps multiple views in sync, reflecting changes to one in all the others, as illustrated in Figure If the result set is empty or if the query failedthe first call to next will return false.
The view classes that inherit QAbstractItemView only need to implement their own view-specific functionality, such qtableview didselectrowatindexpath editing services drawing items, returning the geometry of items, finding items, etc. Although simple to understand and use, this approach doesn't scale very well to large data sets and doesn't lend itself to situations where we want to display the same data set in two or more different widgets.
However, both functions are dangerous unless you know exactly what you are doing and are very careful. To show a tree, QStandardItemModel must be populated with QStandardItem s, which are able to hold all the standard properties of items like text, fonts, checkboxes or brushes.
If open fails, we show an error message. EditRole because our cells only contain text. We set both columns' resize mode to Stretch. The data might be held in files or accessed from a database or a network server.
To start a transaction, we call transaction on the QSqlDatabase object that represents the database connection. If a null pointer was passed as the parent item, we create the item as a child of QTreeWidget:: When we use multiple database connections, we can still have one unnamed connection, and QSqlQuery will use that connection if none is specified.
So for instance if you need a very basic editable item delegate you can do something like this: IconRole, and for these there are convenience setter and getter functions setTextsetIconbut there are several other roles. The iconForSymbol private function returns a QIcon for a given symbol name.
For an easy optimization when operating on large data sets, we can call QSqlQuery:: Now we need to determine how using a separated model impacts the application's performance, so let's trace how often the view calls the data method.
We have also introduced the editCompleted signal, which makes it possible to transfer the modified text to the window title. These functions are convenient, but for some databases they can be slower and more memory-hungry than next. Subsequent calls to next advance the record pointer by one record each time, until the end is reached, at which point next returns false.
I realised that this was a big limitation for the Qt Quick Desktop Componentsso I wanted to see how feasible it would be to add this functionality on top of ListView. For instance, you cannot select items if the selection mode is QAbstractItemView:: To make sure that an item is visible use scrollTo.
Here's an extract from the constructor: The index parameter tells us which field has been edited and value provides the result of the editing process.
So let's create a couple of items: Several other functions are concerned with selection control; for example setSelectionModeand setSelectionBehavior. It iterates over all the keys at the current level in the settings hierarchy and creates one QTableWidgetItem per key. But most desktop applications need more than that to present things like play-lists and albums.
The previously selected item s is not deselected. To update a record, we must first position the QSqlTableModel on the record we want to modify e.
We want to present a real tree. ListView gives you a convenient way to represent a basic flickable list of items.Feb 01, · Hi, guys. I try to add new row dunamically using insertRowsAtIndexPaths.
But I get a small bug: the next group of TableView left trail of caption. Qt model-view: how to suppress model::data DecorationRole when the QTableView cell editor is active I have a delegate to create a QLineEdit control when you want to edit a cell in my subclass of dfaduke.coms: 2.
In Chapter 10, we saw how to use QTableView to present data from a QAbstractItemModel in a table. Since QSqlTableModel is (indirectly) derived from QAbstractItemModel, it can readily be used as the data source of a QTableView. It is expected that the table view contains a lot of data, sometimes more than spreadsheets, have custom delegates for viewing and editing, supports column sorting and row filtering.
And the model view is database-oriented with asynchronous data loading. The QAbstractItemView class provides the basic functionality for item view classes. QAbstractItemView class is the base class for every standard view that uses a QAbstractItemModel. QAbstractItemView is an abstract class and cannot itself be instantiated.
I also tried connecting the doubleClicked() signal from the QAbstractItemView to the edit() slot of the same class, but this only gives me the message edit: editing failed whenever I double click on a cell.Download