Python: Object custom property glitch

Question

I have the following custom prop:

class Settings(bpy.types.PropertyGroup):
    enabled = False 
    state = {
        "some_data": None, # edit: this points to numpy array
        "some_other_data": None
    }        
    string_prop = StringProperty(
        name='Heyyy')

Assigned to:

bpy.types.Object.my_settings = PointerProperty(type=Settings)

There are two issues I am having.

1) I cannot change the value of enabled, like so:

class Init(bpy.types.Operator):
    bl_idname = "object.init"
    bl_label = "Init"
    def execute(self, context):
        context.object.my_settings.enabled = True
        return {'FINISHED'}

2) All of the objects share and control values of state

There are no issues with blender props like the string_prop above.

I assume this is just how Blender handles custom PropertyGroups. Is there a way to make this work? I need to have information stored per object. The only other solution I can think of so far is to store an array of custom props per scene and check which one is currently active based on the id of the selected object, but that is more complicated than I would like it to be.

Answer 1

The boolean flag is the simple part here. As you already assumed, those PropertyGroups are designed to hold Blender Properties only. So instead of

enabled = False

you should use

enabled = BoolProperty(default = False)  // which is anyways the default

The state property is more difficult. There are no Dictionary properties available to you, but maybe you can work around your issue by using a CollectionProperty instead?

Create a class first to hold your collection, for example:

class MyCollection(PropertyGroup):
    val1 = StringProperty()
    val2 = IntProperty(min = 0, max = 999)
    // etc etc

Then, in your Settings class, reference it like this:

variableCollection = CollectionProperty(type = MyCollection)

To add items to the collection, use this in your operator code:

x = context.object.my_settings.variableCollection.add()
x.val1 = 'This works'
x.val2 = 34

Alternatively, you can also nest PropertyGroups of course. That would be

nestedProperties = PointerProperty(type = MyCollection)

That would allow you to do:

context.object.my_settings.nestedProperties.val1 = 'This is nested'
context.object.my_settings.nestedProperties.val2 = 33

It depends on your situation in terms of what works best. But keep in mind that Blender's own property types are the only ones it can store with the file.

One last way to store Python data - but this does not save that data with the file - is simply using a key - value approach on the object. You can always use something like:

x = bpy.context.object
x['myCustomKey'] = myDesiredValue

The resulting data can then even be viewed in the viewport: