QmlModelHelper

Access your models from QML without views or delegates

Installation

1. clone or download this repository
2. add include (<path/to/QmlModelHelper>/QmlModelHelper.pri) in your .pro
3. import ModelHelper 0.1 to use this library in your QML files

Motivation

Sometimes you want to query some model data while not being in a view. You can do so with the Q_INVOKABLE methods of QAbstractItemModels but those returns static result that won't change when the model gets updated. By listening on the QAbstractItemModel signals, this library can expose proper properties with notify signals for easy binding in declarative QML code.

Documentation

To use the ModelHelper, use it as an attached object of a model (it must be a subclass of QAbstractItemModel, meaning it can originate from c++ or be a ListModel from QML).

Attached properties:

rowCount : int

This property holds the number of rows in the model.

count : int

This property holds the number of rows in the model. Alias for rowCount.

columnCount : int

This property holds the number of columns in the model.

roles : array

This property holds an array of objects describing the roles of the model. Each object has 2 properties: role, the number of the role; and roleName, the name of the role.

Attached methods:

object map(int row, int column = 0, QModelIndex parent = {})

Returns a live object mapping an index's data of the model. This is an object with read-write properties named as the model's roles. If the index doesn't exist in the model, the properties will be undefined.

Example: (source problematic from https://stackoverflow.com/questions/41591544/qt-accessing-model-data-outside-itemdelegate/ )

ComboBox {
    id: control
    model: vehiclesModel
    readonly property QtObject currentData: vehiclesModel.ModelHelper.map(control.currentIndex)
    contentItem: RowLayout {
        id: contentItem
        Image { source: control.currentData.imagePath }
        Label { text: control.currentData.name }
    }
    delegate: ItemDelegate {
        contentItem: RowLayout {
            Image { source: model.imagePath }
            Label { text: model.name }
        }
        highlighted: control.highlightedIndex == index
    }
}

This is can be used with the same goal in mind than a QDataWidgetMapper.

int roleForName(string roleName)

Returns the role number for the given roleName. If no role is found for this name, -1 is returned.

var data(int row)

Return the item at row in the model as a map of all its roles.

This can be used in imperative code when you don't need the live updating provided by the map function. Only reading is supported.

var data(int row, string roleName)

Return the data for the given roleName of the item at row in the model.

Similar to data(int row) except that it queries only one role. Prefer this one if you don't need multiple roles for a row.

License

This library is licensed under the MIT License.