🔒 PyQt two-way binding/auto-updating label?

[kindred beacon]

Hey all, new to Qt. I have a few input fields, a calculations based on those, and a label displaying the output. I'm currently manually calling label.setText() whenever the input changes, but as my application grows I foresee this becoming unmanageable. is there a way to have the label (or a disabled input, idc) automatically listen to changes on an internal value?

[prime nexus]

@kindred beacon

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[shell cargo]

you can add a textChanged signal connected to all your input fields

[kindred beacon]

I intend to, but I don't wanna call setText() directly. Right now these fields and labels are close together, but as the app grows I'd like something more elegant

[shell cargo]

this is a pretty common implementation

self.some_input_field.textChanged.connect(self.on_field_updated)

and then they can all connect to this same self.on_field_updated method

and from there, you handle what happens when text changes

as a similar example, this is a tool I wrote for exporting animations from animation software

the fields are all connected to the same method

the text of the field changes to orange if the filename exists (just as a warning that you will be overwriting)

it uses textEdited to achieve this

[frail kraken]

looks good

[kindred beacon]

Ok, I think that helps, gonna try that! tyvm!

[shell cargo]

another example

this tells you what the filename you'll be creating will be named based on the text fields

[shell cargo]

Haha hey! Thanks!

[frail kraken]

😮 you nazi ! why don't you let the user pick the name directly ?

[kindred beacon]

And in that case, it's not the input field that triggers the update chain for the label?

[shell cargo]

because certain characters will need unique animation names and we don't have a source of data yet 😬

[shell cargo]

it does. Every time ANY of these fields are updated, it queries the text of all the fields and constructs the new string, then updates the label

self.asset_name_line.textChanged.connect(self.update_filepath_label)
self.scene_name_line.textChanged.connect(self.update_filepath_label)
self.version_line.valueChanged.connect(self.update_filepath_label)

here's my connections

[kindred beacon]

But there's no way to like, store the full name in an observable value that the label can connect to?

[shell cargo]

def update_filepath_label(self):
    asset = self.asset_name_line.text().strip('_')
    scene = self.scene_name_line.text().strip('_').title()
    num = '{:03d}'.format(self.version_line.value())
    filename = '{}_{}_{}.ma'.format(asset, scene, num)
    self.filepath_label.setText(filename)

and my method

[shell cargo]

I could update an attribute or something with that name if I wanted to

but there's really no reason to. I query the value as needed

there's not really a benefit to storing it elsewhere

[kindred beacon]

I understand that's simpler in your use case, but it doesn't solve my issue

[shell cargo]

Perhaps you can elaborate then

in my use case, I just query the label text to get the filename I'm meant to create

I don't need a separate variable to get that filename

[kindred beacon]

As my app grows, I expect inputs and labels all over the place, all interconnected.
I wanna keep my data centralized

[shell cargo]

but if any single one of them changing needs to update a label somewhere, then that's your option

when a field changes, figure out what to display from a method

[kindred beacon]

Specifying all labels that need an update post calculation is what I'm trying to avoid

[shell cargo]

are you worried about speed?

[kindred beacon]

Not really, just wanna keep direct UI calls out of my logic

[shell cargo]

signals is really the only way to keep information "live"

that's really what they're there for

[kindred beacon]

So there's no observables?

[shell cargo]

I don't believe so

[kindred beacon]

sigh the hard way it is then. ty

!close

[prime nexus]

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