Import problems with forms

[viggobryantfrost]

What I’m trying to do:
I am trying to import the ‘parent’ form of this component, so that I can call functions in it. The circumstances:

This is a ‘files’ app so you can save text files. I am trying to add functionality to sort these files into ‘folders’. The Folder template, component form, repeated in a LinearPanel, which is passed the folder name from HomeScrn as a property, has a button on it that when clicked is supposed to change the folder shown on the page for the file app (HomeScrn). But here’s where problems occured:

I couldn’t import the HomeScrn form - AttributeError; ‘HomeScrn has no attribute HomeScrn’ - in the Folder component form, despite following the dropdown suggestions in Code.

Help!

PS If you need further explanation just say. Unfortunately it’s quite hard to clone the app, sorry.

[campopianoa]

Hello and welcome,

The details are a little unclear to me in terms of being able to give an exact answer. Could you clone a small app that demonstrates the issue (not your actual app)? This would really help.

In general though you could search the forum and docs for:

• importing forms
• how to call a function from another form
• how to pass variables between forms

There should be a lot of helpful info there that will likely be relevant.

[viggobryantfrost]

Hi,

I will try to cook up a small app which demonstrates what I am trying to do - as it’s only involving two forms.

Thanks for your advice re the subject of importing forms/calling functions from others, I’ll try to further research.

[p.colbert]

In C/C++, you would need to #include the parent form’s definition, in order for the compiler to understand what type it’s dealing with, and make calls to objects of that type.

In Python, you don’t need to do that. Once an object (the parent form) exists, it carries all those details with it, for last-instant lookup. Once you get a reference to that object, that’s sufficient for accessing all of the object’s members, including members that happen to be functions.

[viggobryantfrost]

Hello again,

I have a cloned mini-app, which is experiencing the same error as the actual app. It’s quite simple really.

https://anvil.works/build#clone:S6CMNJG2QTF3ZW3N=RQZCGPRSZMG2YYGWRQQQGASZ

[stucork]

It looks like you have a circular import which doesn’t work in python3

Here are some related questions that might help you solve the problem.

Avoiding circular imports in two forms referencing each other

I have a master form with a navigation column. Within the content_panel, I have subforms (opened through add_component) that should link to each other: Form A from B import B def btn_other_form_click(self): get_open_form().content_panel.clear() get_open_form().content_panel.add_component(B()) Form B from A import A def btn_other_form_click(self): get_open_form().content_panel.clear() get_open_form().content_panel.add_component(A()) This creates a circular reference, and …

ImportError: no module named foo; AttributeError: 'module' object has no attribute 'bar'

This is likely to be a circular import You are possibly doing something like: Form A: from ..FormB import foo Form B: from ..FormA import bar or likewise Form A: from .. import FormB Form B: from .. import FormA One option you can move import statements into methods or classes to prevent them being circular Form A: from ..FormB import foo Form B: def some_method(): from ..FormA import bar # no longer a circular import or likewise Form A: from .. import FormB Form B: …

[viggobryantfrost]

I have a solution !

Thanks for your help, @alcampopiano, @p.colbert and @stucork - I didn’t previously know you couldn’t circular import, let alone know what that was.

So basically, I just got rid of the need for the circular import, and on the HomeScrn form (see cloned app), just changed the LinearPanel to a RepeatingPanel so there’s no need to import the components.

Fingers crossed, this won’t fail me too! PS you can find my actual published app, currently under development but half done at vsuite3.anvil.app (moving soon to vsuite.anvil.app). It’s an app aiming to be similar to, but much more simple than O365 and G Suite etc.

Thanks again for your help!