forked from qt-creator/qt-creator
a3fbc85ced
Restructure existing information and fix navigation links. Fixes: QDS-4470 Change-Id: I4a1118a4620527b461b99bf05b8b06d947018c80 Reviewed-by: Johanna Vanhatapio <johanna.vanhatapio@qt.io>
124 lines
4.1 KiB
Plaintext
124 lines
4.1 KiB
Plaintext
/****************************************************************************
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**
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** Copyright (C) 2021 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the Qt Creator documentation.
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**
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Free Documentation License Usage
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** Alternatively, this file may be used under the terms of the GNU Free
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** Documentation License version 1.3 as published by the Free Software
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** Foundation and appearing in the file included in the packaging of
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** this file. Please review the following information to ensure
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** the GNU Free Documentation License version 1.3 requirements
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** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
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**
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****************************************************************************/
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/*!
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\page qtquick-placeholder-data.html
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\previouspage studio-simulation-overview.html
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\if defined(qtdesignstudio)
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\nextpage studio-javascript.html
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\else
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\nextpage creator-qml-modules-with-plugins.html
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\endif
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\title Loading Placeholder Data
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\QC supports views, models, and delegates, so that when you add
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a Grid View, List View, or Path View component, the ListModel and
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the delegate component are added automatically.
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However, the missing context of the application presents a challenge.
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Specific models defined in C++ are the most obvious case. Often,
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the context is missing simple properties, which are either defined in C++,
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or in other component files. A typical example is a component that uses the
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properties of its parent, such as \c parent.width.
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\section1 Using Dummy Models
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If you open a file in \l {Form Editor} that references a C++ model, you see
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nothing in it. If the data in the model is fetched from the
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internet, you have no control over it. To get reliable data, \e {dummy data}
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was introduced.
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For example, the following code snippet describes the file example.qml that
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contains a ListView that in turn specifies a C++ model:
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\qml
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ListView {
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model: dataModel
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delegate: ContactDelegate {
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name: name
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}
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}
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\endqml
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Create a directory named \e dummydata in the root directory of the project,
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so that it is not deployed to the device. In the \c dummydata directory,
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create a file (.qml) that has the same name as the value of \c model:
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\code
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qml/exampleapp/example.qml
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dummydata/dataModel.qml
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\endcode
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Then create the dataModel.qml file that contains the dummy data:
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\qml
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import QtQuick 2.0
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ListModel {
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ListElement {
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name: "Ariane"
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}
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ListElement {
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name: "Bella"
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}
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ListElement {
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name: "Corinna"
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}
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}
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\endqml
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\section1 Creating Dummy Context
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The following example presents a common pattern:
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\qml
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Item {
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width: parent.width
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height: parent.height
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}
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\endqml
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This works nicely for applications but \uicontrol {Form Editor} displays a
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zero-sized component. A parent for the opened file does not exist, because
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the context is missing. To get around the missing context, the idea of a
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\e {dummy context} is introduced. If you place a file with the same name as
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the application (here, example.qml) in the \c {dummydata/context} directory,
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you can fake a parent context:
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\qml
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import QtQuick 2.0
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import QmlDesigner 1.0
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DummyContextObject {
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parent: Item {
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width: 640
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height: 300
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}
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}
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\endqml
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*/
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