CollectionProperty with unique names

Coding Python Support
1

Hi,

how can I ensure that my CollectionProperties uses only unique names. For types like bpy.types.Object or marerials renaming is done automatic (“Cube”, “Cube.001” and so on). If I have a Collection of PropertyGroup, items of can have the same name. It is possible to add a update function to the name property of of the PropertyGroup, which solves the problem in sone cases.

class MyGroup(bpy.types.PropertyGroup):
    def update_name(self, context):
        print("queue update_name - Code to handle double names goes here")

    name = bpy.props.StringProperty(default='name', update=update_name)

If I change the name of the Collection Item on the python console, the update_name function is executed, but if I use the Collection in an UI element like “template_list” and change the name there, the update function is not called, and I still can give the same name to different items.

Pointers are welcome.

Regards offtools.

2

That is because ‘name’ is reserved for the name of the python collection element (which does not support Blender update events). Try making a string property called ‘entry_name’ or something. Then attach an update to that property. In your draw routine do not display the ‘name’ property. Instead display the ‘entry_name’ property. This way you will get an event and you can handle the name change as you see fit.

Personally I gave up allowing users to rename entries in a list and simply manage the list with automatic naming convention.

3

Thanks for your reply and the explanation. Pointed me to the right direction, I found another solution by using a custom draw class for the template_list, which calls the update_name callback correct.

class MYGROUP_UL_custom(bpy.types.UIList):
         def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
                 mygroup = data
                 groupitem = item
                 layout.prop(groupitem, 'name', text='', emboss=False)

Changing the name of the element with prop will work and call the update_name callback. Setting Emboss to False make your prop entry look like a label, but is still editable

# UI Code
...
row.template_list("MYGROUP_UL_custom", "mygroup", context.scene, "mygroup", context.scene, "active_group_element", rows=2, maxrows=8)
...

offtools