[Interest] getting type information of properties in QML

[Mike Trahearn]

Hello Federico,

Here’s a little test I put together based on your description.

1) use pragma ValueTypeBehavior: Addressable
https://doc.qt.io/qt-6/qtqml-documents-structure.html#valuetypebehavior

Among other things, this makes it possible to use value types with instanceOf.

2) Value types can be assigned property-wise as shown below.

3) types like int are not value types so they have to be treated differently in your case. However, Number.isInteger(n) may get you close.

4) So far as I can see, which types are value types and which are not is not really explained in the following page (for which I have requested):

https://doc.qt.io/qt-6/qtqml-typesystem-valuetypes.html#built-in-value-types-provided-by-the-qml-language

However if you go and find the definitions of these in the code, you can see the properties you can assign for each of the value types:

https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/util/qquickvaluetypes_p.h

Hope this helps,

Mike





> On 16 Jul 2024, at 8:10 PM, Federico Ferri <federico.ferri.it at gmail.com> wrote:
> 
> Is there any way to get type information about types of properties defined in a QML Component?
> 
> e.g.
> 
> Item {
>     property color c
>     property vector3d v
>     property int i
> 
>     Component.onCompleted: {
>         getPropertyType(c) === 'color'
>         getPropertyType(v) === 'vector3d'
>         getPropertyType(i) === 'int'
>     }
> }
> 
> Details on my usecase: I receive messages over network that decode to JS objects, but values such as colors and 3d vectors are encoded as simple JS arrays (e.g. [0.0, 0.5, 1.0]) and direct assignment to the above properties won't work.
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