[QML Runtime Tool - Qt 6.2] Using dummydata folder

nico88desmo

Hi everybody,

I'm prototyping some UI QML files using qml runtime tool: regarding model data, I'd like using dummydata folder as used using old qmlscene tool.

Using the same setup, if I'm using qmlscene, everything correctly works; using qml instead, dummy model data isn't load.

Using the comman qml --help, options dummydata exists, however it seems not working as expected.

/usr/local/Qt-6.2.7/bin/qml --help
Usage: /usr/local/Qt-6.2.7/bin/qml [options] [files...] [-- args...]

Options:
  -h, --help                       Displays help on commandline options.
  --help-all                       Displays help including Qt specific options.
  -v, --version                    Displays version information.
  -a, --apptype <core|gui|widget>  Select which application class to use.
                                   Default is gui.
  -I <path>                        Prepend the given path to the import paths.
  -f <file>                        Load the given file as a QML file.
  -c, --config <file>              Load the given built-in configuration or
                                   configuration file.
  --list-conf                      List the built-in configurations.
  --translation <file>             Load the given file as the translations
                                   file.
  --dummy-data <file>              Load QML files from the given directory as
                                   context properties.
  --desktop                        Force use of desktop OpenGL
                                   (AA_UseDesktopOpenGL).
  --gles                           Force use of GLES (AA_UseOpenGLES).
  --software                       Force use of software rendering
                                   (AA_UseSoftwareOpenGL).
  --core-profile                   Force use of OpenGL Core Profile.
  --disable-context-sharing        Disable the use of a shared GL context for
                                   QtQuick Windows
  --quiet                          Suppress all output.
  --verbose                        Print information about what qml is doing,
                                   like specific file URLs being loaded.
  --slow-animations                Run all animations in slow motion.
  --fixed-animations               Run animations off animation tick rather
                                   than wall time.
  -r, --rhi <backend>              Set the backend for the Qt graphics
                                   abstraction (RHI). Backend is one of:
                                   default, vulkan, metal, d3d11, gl
  -S <selector>                    Add selector to the list of
                                   QQmlFileSelectors.

Arguments:
  files                            Any number of QML files can be loaded. They
                                   will share the same engine.
  args                             Arguments after '--' are ignored, but passed
                                   through to the application.arguments variable
                                   in QML.

The folder structure used respects the following one:

project
├── Main.qml
└── dummydata/
    └── SampleModel.qml

where SampleModel.qml is the following

import QtQuick

ListModel {
    ListElement {
        name: "Prova 1"
        printingTimeS: 50
        details: "Prova 1 description"
    }
    ListElement {
        name: "Prova 2"
        printingTimeS: 20
        details: "Prova 2 description"
    }
}

and Main.qml has the following piece of code:

...

   ListView {
       anchors.fill: parent

       model: SampleModel

       delegate: Column {
           Text { text: "Nome: " + name }
           Text { text: "Tempo: " + printingTimeS + "s" }
           Text { text: "Dettagli: " + details }
       }
   }
...

I don't find anything on official Qt documentation regarding this aspect.

Any idea?

Thanks in advance,
Nicola

nico88desmo

@SGaist I try renaming SampleModel.qml to sampleModel.qml, but qml is not able to load dummy model.

However, I find the solution watching qml tool source code.
Using Qt 6.2, the solution to load dummy-data is the following: supposing this folder structure

project
├── Main.qml
└── dummydata/
    └── SampleModel.qml

the steps are:

set project folder as workdir (so, qml need to be execute within project path)
execute the command
qml --dummy-data . Main.qml

Important note: since Qt 6.3, dummy-data options seems marked obsolete (from qml source code)

SGaist

Hi,

Just a shot in the dark based on the documentation of qmlscene but: try renaming your file sampleModel.qml and apply the same logic in the code.

nico88desmo

@SGaist I try renaming SampleModel.qml to sampleModel.qml, but qml is not able to load dummy model.

However, I find the solution watching qml tool source code.
Using Qt 6.2, the solution to load dummy-data is the following: supposing this folder structure

project
├── Main.qml
└── dummydata/
    └── SampleModel.qml

the steps are:

set project folder as workdir (so, qml need to be execute within project path)
execute the command
qml --dummy-data . Main.qml

Important note: since Qt 6.3, dummy-data options seems marked obsolete (from qml source code)

GrecKo

Instead of using --dummy-data you could provide a module with a SampleModel singleton and use different import paths depending on if you want an actual model or a mock one.

nico88desmo

@GrecKo that was the other idea.

But It means creating a QML module just for dummy model used for ui prototype; and I don't like to release that module on production code.

Example

Form.ui.qml

import com.myrealmodule
import com.mydummymodule
...
// Here I use singleton for dummy data
...

However if I don't release that dummy module, clearly I have runtime problem when application starts, cause it.s not able to find It.