Blender is crashed when the properties are dynamically created by bpy.types.CollectionProperty #84399

New Issue

nutti · 2021-01-05T10:12:02+01:00

nutti commented

2021-01-05 10:12:02 +01:00

System Information
Operating system: macOS 10.14.6
Graphics card: Radeon Pro 450

Blender Version
Broken: 2.91
Worked: 2.80

Short description of error

Blender is crashed when the properties are dynamically created by bpy.types.CollectionProperty .

I want to create an add-on which changes the number of bpy.types.BoolProperty dynamically along with the context.
But, Blender will crash when I changes the status of dynamically created checkbox.

NOTE: I doubt that this issue may come from the incorrect usage of bpy.types.CollectionProperty, but I'm not sure.

Exact steps for others to reproduce the error

I will attach the simple add-on which reproduces this error.

collection_prop.py

Install the attached add-on.
Enable add-on "Collection Property".
Click File > Import > Test Op.
From right most region, you can see the checkbox list labeled by the numbers

Click checkbox some times, then Blender will crash.

I will also attach the crash report.

blender.crash.txt

**System Information** Operating system: macOS 10.14.6 Graphics card: Radeon Pro 450 **Blender Version** Broken: 2.91 Worked: 2.80 **Short description of error** Blender is crashed when the properties are dynamically created by bpy.types.CollectionProperty . I want to create an add-on which changes the number of bpy.types.BoolProperty dynamically along with the context. But, Blender will crash when I changes the status of dynamically created checkbox. *NOTE: I doubt that this issue may come from the incorrect usage of bpy.types.CollectionProperty, but I'm not sure.* **Exact steps for others to reproduce the error** I will attach the simple add-on which reproduces this error. [collection_prop.py](https://archive.blender.org/developer/F9551174/collection_prop.py) - Install the attached add-on. - Enable add-on "Collection Property". - Click **File** > **Import** > **Test Op**. - From right most region, you can see the checkbox list labeled by the numbers # Click checkbox some times, then Blender will crash. I will also attach the crash report. [blender.crash.txt](https://archive.blender.org/developer/F9551182/blender.crash.txt)

nutti commented

2021-01-05 10:12:02 +01:00

Added subscriber: @nutti

Falk David commented

2021-01-05 14:17:19 +01:00

Added subscriber: @filedescriptor

Falk David commented

2021-01-05 14:17:19 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Falk David commented

2021-01-05 14:17:19 +01:00

I can reproduce the crash on 2.92.0 Alpha, branch: master, commit date: 2021-01-05 07:03, hash: 08f00f4f6e.

I can reproduce the crash on 2.92.0 Alpha, branch: master, commit date: 2021-01-05 07:03, hash: `08f00f4f6e`.

Robert Guetzkow commented

2021-01-05 15:36:39 +01:00

Added subscriber: @rjg

Robert Guetzkow commented

2021-01-05 15:36:39 +01:00

Changed status from 'Confirmed' to: 'Archived'

Robert Guetzkow closed this issue

2021-01-05 15:36:39 +01:00

Robert Guetzkow commented

2021-01-05 15:36:39 +01:00

The issue appears to be that you are adding references to the items you're adding to another list which you then use to add the properties to the layout. This list is cleared in the draw function, possibly leading to invalid references. Additionally, you are clearing and adding to the CollectionProperty on every draw. This means even if it doesn't crash, you can't actually do anything useful with the properties because they are replaced on the next draw of the UI along with their value.

You can see this in the following version, which shouldn't crash but doesn't actually let you use the checkboxes.

import bpy
from bpy.props import CollectionProperty, BoolProperty
from bpy_extras.io_utils import ImportHelper


bl_info = {

"name": "Collection Property",
"author": "nutti",
"version": (1, 0, 0),
"blender": (2, 91, 0),
"location": "",
"description": "",
"support": "COMMUNITY",
"category": "UV"

}

class BoolPropertyCollection(bpy.types.PropertyGroup):

checked: BoolProperty(name="", default=True)



class TEST_OT_TestOp(bpy.types.Operator, ImportHelper):

bl_idname = "uv.test_op"
bl_label = "Test Op"
bl_description = "Test Operator"
bl_options = {'REGISTER', 'UNDO'}

bool_prop_collection: CollectionProperty(type=BoolPropertyCollection)

def draw(self, context):
layout = self.layout

  self.bool_prop_collection.clear()
  for i in range(200):
      item = self.bool_prop_collection.add()
      item.name = str(i)
      
  for d in self.bool_prop_collection:
      layout.prop(d, "checked", text=d["name"])

def execute(self, context):
return {'FINISHED'}

def invoke(self, context, event):
wm = context.window_manager
wm.fileselect_add(self)

  return {'RUNNING_MODAL'}



def menu_fn(self, _):

layout = self.layout
layout.operator(TEST_OT_TestOp.bl_idname)



def register():

bpy.utils.register_class(BoolPropertyCollection)
bpy.utils.register_class(TEST_OT_TestOp)

bpy.types.TOPBAR_MT_file_import.append(menu_fn)



def unregister():

bpy.types.TOPBAR_MT_file_import.remove(menu_fn)

bpy.utils.unregister_class(TEST_OT_TestOp)
bpy.utils.unregister_class(BoolPropertyCollection)



if __name__ == "__main__":

register()

As far as I can see this is not a bug in Blender, just an issue with an improperly implemented script. For questions on script development I would suggest you ask questions on one of our [community websites ]], for instance https:*blender.stackexchange.com/ , https:*blenderartists.org/ or the [ https:*blender.chat/channel/support | #support channel on Blender chat .

The issue appears to be that you are adding references to the items you're adding to another list which you then use to add the properties to the layout. This list is cleared in the draw function, possibly leading to invalid references. Additionally, you are clearing and adding to the `CollectionProperty` on every draw. This means even if it doesn't crash, you can't actually do anything useful with the properties because they are replaced on the next draw of the UI along with their value. You can see this in the following version, which shouldn't crash but doesn't actually let you use the checkboxes. ```lines import bpy from bpy.props import CollectionProperty, BoolProperty from bpy_extras.io_utils import ImportHelper bl_info = { ``` "name": "Collection Property", "author": "nutti", "version": (1, 0, 0), "blender": (2, 91, 0), "location": "", "description": "", "support": "COMMUNITY", "category": "UV" ``` } class BoolPropertyCollection(bpy.types.PropertyGroup): ``` checked: BoolProperty(name="", default=True) ``` class TEST_OT_TestOp(bpy.types.Operator, ImportHelper): ``` bl_idname = "uv.test_op" bl_label = "Test Op" bl_description = "Test Operator" bl_options = {'REGISTER', 'UNDO'} ``` ``` bool_prop_collection: CollectionProperty(type=BoolPropertyCollection) ``` ``` def draw(self, context): layout = self.layout ``` ``` self.bool_prop_collection.clear() for i in range(200): item = self.bool_prop_collection.add() item.name = str(i) for d in self.bool_prop_collection: layout.prop(d, "checked", text=d["name"]) ``` ``` def execute(self, context): return {'FINISHED'} def invoke(self, context, event): wm = context.window_manager wm.fileselect_add(self) ``` ``` return {'RUNNING_MODAL'} ``` def menu_fn(self, _): ``` layout = self.layout layout.operator(TEST_OT_TestOp.bl_idname) ``` def register(): ``` bpy.utils.register_class(BoolPropertyCollection) bpy.utils.register_class(TEST_OT_TestOp) ``` ``` bpy.types.TOPBAR_MT_file_import.append(menu_fn) ``` def unregister(): ``` bpy.types.TOPBAR_MT_file_import.remove(menu_fn) ``` ``` bpy.utils.unregister_class(TEST_OT_TestOp) bpy.utils.unregister_class(BoolPropertyCollection) ``` if __name__ == "__main__": ``` register() ``` ``` As far as I can see this is not a bug in Blender, just an issue with an improperly implemented script. For questions on script development I would suggest you ask questions on one of our [community websites ]], for instance [[ https:*blender.stackexchange.com/ | Blender's StackExchange ]], [[ https:*blenderartists.org/ | blenderartists.org ]] or the [[ https:*blender.chat/channel/support | #support channel on Blender chat ](https:*www.blender.org/community/).

nutti commented

2021-01-06 09:59:53 +01:00

@rjg

Thanks!
I will redirect this question to the other place.

@rjg Thanks! I will redirect this question to the other place.

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Blender is crashed when the properties are dynamically created by bpy.types.CollectionProperty #84399

Click checkbox some times, then Blender will crash.