QIODevice cannot open .ui file from resources.

zspinelli

I'm trying to use the FormBuilder class to load ui files from project resources I get the error:

QIODevice::read (QFile, ":\_qtresources\ui\NewDocumentForm.ui"): device not open
Designer: An error has occurred while reading the UI file at line 1, column 0: Premature end of document.

Here is what is loading it:

class NewDocumentForm(QDialog):
    accepted = Signal()

    def __init__(self):
        super().__init__()

        form = QFile(":/_qtresources/ui/NewDocumentForm.ui")
        form.open(QFile.ReadOnly)

        builder = QFormBuilder()
        builder.load(form, self)

I can only guess that it's somehow not finding the ui file since the qiodevice turns up effectively empty.

JonB

@zspinelli
For the error message, that comes from trying to load from a non-open file. form.open(QFile.ReadOnly) returns a boolean to indicate success/failure, and I would guess its returning False. QIODevice.errorString() might provide more information.

zspinelli

@JonB
The errorString gives me "No such file or directory"

JonB

@zspinelli
So that's the explanation for the error! That's all I was saying.

zspinelli

@JonB
I just found something now for a tool called rcc. Is that absolutely always neccessary to use qrc stuff?
If so, I think this might be the problem.

JonB

@zspinelli
I assume your form resource is not at :/_qtresources/ui/NewDocumentForm.ui.

zspinelli

@JonB
That's the exact path to it from the top of the source directory in the file system.
That's the path resources gave it when I added the form to the project.
I don't know where it would be if it's not there.

SGaist

Hi,

@zspinelli said in QIODevice cannot open .ui file from resources.:

@JonB
I just found something now for a tool called rcc. Is that absolutely always neccessary to use qrc stuff?
If so, I think this might be the problem.

Yes that is mandatory. Resources must be first created like in C++. See here.

JonB

@zspinelli said in QIODevice cannot open .ui file from resources.:

That's the exact path to it from the top of the source directory in the file system.

That's not what you want at runtime. The :/... file path syntax is treated by Qt as referring to a resource compiled into your executable, not a real, external file. Follow @SGaist's link to achieve that.

zspinelli

@SGaist
The link you posted shows an example using a tool called "pyside6-rcc".
If that's supposed to be installed with PySide6 then for some reason I don't have it. I found this page https://stackoverflow.com/questions/22479581/cannot-use-pyside-rcc-to-compile-qrc-file mentioning some locations where it might be but it isn't present in any of them.

However I found another page: https://doc.qt.io/qtforpython/overviews/resources.html showing the use of the regular "rcc" which I do have as part of the Qt installation. Before I try the example shown there, should I know if one is one tool is more preferable than the other?

SGaist

If the one you have supports Python code generation, then use it.

zspinelli

I found pyside6-rcc. I'm going to note for posterity that it was found under C:\Users\<username>\AppData\Roaming\Python\Python39\Scripts

I ran it, got the py output as per the demonstration, and imported it. The errorString for the QFile is now "Unknown error".

zspinelli

@JonB @SGaist
After lot of internet searching and fistfighting the code, I got my project back on track and got some other stuff fixed as well.
I had pyside6 module installed wrong and was using the wrong approach for integrating the UI form.
@SGaist Your recommendation for pyside6-rss led me to pyside6-uic, which was what I really needed.

I'm thankful to you both for tolerating and assisting me.