Handle Platform specific imports

SyntaX

Hey there :D

I am trying to build my application for WebAssembly and found out, that QtQuick.LocalStorage is not supported (still searching for an alternative / best practice to save local data in Wasm):

> module "QtQuick.LocalStorage" is not installed

(on Firefox)

So I wanted to temporary exclude the import in the QML file, but I don't know how?
Doing with macros like in C++ code does not work

#ifndef Q_OS_WASM // error: Unexpected token `'
    import QtQuick.LocalStorage 2.12
#endif

neither the platform flags I use in the project file

Wasm {
    import QtQuick.LocalStorage 2.12 // error: Unexpected token 'import'
}

or a classic if to get platform information

if (Qt.platform.os != "wasm") // error: Unexpected token 'if'
    import QtQuick.LocalStorage 2.12
}

Is there a way I can solve this so I can further investigate the WebAssembly build?
Or is the conventional way to have different implementations for Wasm and iOS/Android/macOs? (Maybe https://doc.qt.io/qt-5/qqmlfileselector.html is the way to go?)
Or maybe there exists a common way to use LocalStorage on all platforms?

Thanks for any information,
best regards SyntaX

J.Hilk

Hi @SyntaX

sadly, there is currently only really one (cumbersome) way to exclude stuff depending on flags, in QML

By Shoveling everything it its own qml file and using a Loader, to conditionally load.

IIRC this should change with Qt6, there we should get something along the line if #if #else #endif

SyntaX

Thanks @J-Hilk for your reply, I will investigate the QML Loader type :D
https://doc.qt.io/qt-5/qml-qtquick-loader.html

lorn.potter

@SyntaX said in Handle Platform specific imports:

I am trying to build my application for WebAssembly and found out, that QtQuick.LocalStorage is not supported (still searching for an alternative / best practice to save local data in Wasm):

The only way to open and save data to the local (desktop) filesystem with wasm is to use
QFileDialog::getOpenFileContent
and
QFileDialog::saveFileContent

https://doc.qt.io/qt-5/qfiledialog.html#saveFileContent

Also, currently there is no support for SQL or other databases in Qt WebAssembly.

SyntaX

Hey @lorn-potter and thanks for your reply and the provided information!