How to properly expose data to View when the data is different than exposed model

ChrisTof

I am implementing model-view using C++ data.
I have a c++ class with data:

class TransactionsList: public QObject
{
    Q_OBJECT
public:
    //....
private:
    QVector<Transaction> transactions;
};

I have the model:

class TransactionsModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(TransactionsList *modelTransactions READ getTransactions WRITE setTransactions)
// ...
private:
    TransactionsList *transactions;
};

And the view:

TableView {
    id: transactionsTable
    anchors.fill: parent
    // ...
    model : TransactionsModel {
        id: transactionsModel;
        modelTransactions: transactions
    }

And TransactionsList created and exposed to QML in main.cpp:

TransactionsList transactions;
engine.rootContext()->setContextProperty(QStringLiteral("transactions"), &transactions);

I want to add ChartView that displays sums of transactions amounts for categories. I started like this:

ChartView {
    //...
    PieSeries {
        id: pieSeries
    }

    function generateCategoriesAndAmounts() {
        var categories = getCategories(); // <<< returns set of unique categories.
        var amounts = getCategoriesAmounts(); // <<<
        // Append to pieSeries ...
   }
   Component.onCompleted: {
        pieSeries.generateCategoriesAndAmounts();
    }

Where should getCategories() and getCategoriesAmounts() functions be implemented? In the TransactionsModel or in the TransactionsList class?

sierdzio

@ChrisTof said in How to properly expose data to View when the data is different than exposed model:

Where should getCategories() and getCategoriesAmounts() functions be implemented? In the TransactionsModel or in the TransactionsList class?

In model.

The views should not know anything about the underlying data.

ChrisTof

main.qml looks like this:

Window {
    //...
    Item {
        id: listViewContainer
        //...

        ListView {
            id: listview
            //...
            model: ListModel {
                ListElement {component: "Datasheet.qml"; } // TableView
                ListElement {component: "PieChart.qml"}
                ListElement {component: "BarSeries.qml"}
            }
            delegate: Loader { //... }

I know how to make use of the TransactionsModel in Datasheet.qml

model: TransactionsModel{
            id: transactionsModel;
            modelTransactions: transactions }

How can I define this model once in the main.qml and distribute it to Datasheet.qml, PieChart.qml, BarSeries.qml?
Or is it not how it should be done?
Should I have three models, each for Datasheet.qml, PieChart.qml, BarSeries.qml?